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Welding Inspection
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Ir.Soeweify, M.Eng
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Head of Strength and Structure Groups
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Department of Shipbuilding Engineering
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Surabaya Institute of Technology
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Welding Engineer 1980 Hiroshima University
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Welding Inspector 1984 Hamburg University
Fracture Mechanic 1990 Bandung Institute of Technology
Ir. Soeweify, M.Eng
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• Under Graduate S1 from Faculty of Shipbuilding
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Eng. ITS 1974
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• Graduate S2 from Departement Shipbuilding
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Engineering Hiroshima University Japan 1980
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• Welding Engineer Hiroshima Univ Japan 1980
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• Welding Inspector Hamburg Univ Germany 1984
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• Fracture Mechanic Department of Mechanical
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Engineering ITB Bandung 1990
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Professional ocupation
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• Head of Construction laboratory 1981
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1991
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• Head of Welding Laboratory 1987 -1991
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• Dean of the Faculty of Marine Technology
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1990 – 1993
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• Head of Strength and Structural group
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Department of Naval Architecture and
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Shipbuilding Engineering 1997 till now
Studies and conferences aboards
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• Study on Welding deformation Hiroshima
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University Japan 1980
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• Study of fatigue life welded structure Hamburg
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University Germany 1984
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• Study on influences of marine growth on fatigue
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offshore structure Newcastle Upon Tyne and
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Glasgow University UK 1992
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• Study works on “ Just on time System” in
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Nakatani shipbuilding Engineering Takahashi
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Japan 1995
Studies and conferences aboards
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• Study on LNG domestic transportation
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Osaka, Himeji, Kawasaki Japan 2005
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• Study on LNG International transportation
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Guangze China, Kobe, Kita kyushu, Chiba
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Japan 2007
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• Internal Institute of Welding conference
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Bangkok 2005
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• Internal Institute of Welding conference
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Singapure 2009
Organization
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• PII as member since 1975
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• JSNA as member1978-1985
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• Persada head of Jawa Timur branch 1998
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-2005
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• HATMI as a member and founder 1992
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• IWS member of board of experties 1998
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now
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• IWS head of adviser board of Surabaya
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Chapter 2008
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WELDING TECHNOLOGY
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Teknik Las
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INTRODUCTION
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NONMANDATORY REFERENCES
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• Althouse, Andrew R, et. al., Modern Welding, The Goodheart-
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Willcox Company, Inc., Illinois, 1988.
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• ASME, 1998 ASME Boiler & Pressure Vessel Code, Section IX -
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Welding and Brazing Qualification, The American Society of
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Mechanical Engineers, New York, 2000.
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• AWS, AWS D1.1: 2002, Structural Welding Code - Steel, American
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Welding Society, Miami, 2002.
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• AWS, Certification Manual for Welding Inspectors, American
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Welding Society, Miami, 4th Edition, 2000.
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NONMANDATORY REFERENCES
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• AWS, ANSI/AWS A3.0-94, Standard Welding Terms and Definitions,
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American Welding Society, Miami, 1994.
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• AWS, Welding Inspection Handbook, American Welding Society,
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Miami, 3rd Edition, 2000.
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• Jeffus, Larry, Welding - Principles and Applications, Delmar
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Publishers Inc., Albany, 3,d Edition, 1993.
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• Jenney, Cynthia L., and Annette O'Brien, Welding Handbook,
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Volume 1 - Welding Science and Technology, American Welding
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Society, Miami, 9th Edition, 2001.
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NONMANDATORY REFERENCES
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• O'Brien, R.L., Welding Handbook, Volume 2 - Welding Processes,
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American Welding Society, Miami, 8th Edition, 1991.
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• Oates, William R., Welding Handbook, Volume 3 - Materials &
Applications Part l, American Welding Society, Miami, 8th Edition,
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1996.
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• Oates, William R., and Alexander M. Saitta, Welding Handbook,
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Volume 3 – Materials & Applications Part 2, American Welding
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Society, Miami, 8th Edition, 1998.
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MANDATORY REFERENCES
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Wiryosumarto, Harsono, dan Toshie
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Okumura, Teknologi Pengelasan
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Logam, Pradnya Paramita, Jakarta,
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Cetakan Kedelapan, 2000.
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JOINING METHOD CHART
Early metal-joining methods included such processes as forming a sand
mold on top of a piece of metal and casting the desired shape directly on
the base metal, Figure 1-1
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Another metal-joining method used in early years was to place two pieces
of metal close together and pour molten metal between them. When the
edges of the base metal melted, the flow of metal was then dammed and
allowed to harden. Figure 1-2.
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The Industrial Revolution, from 1750
to 1850, introduced a method of
joining pieces of iron together known
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as forge welding or hammer
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welding.
welding
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This process involved the use of a forge to
heat the metal to a soft, plastic
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temperature. The ends of the iron were
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then placed together and hammered
until fusion took place.
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Forge welding remained as the primary welding method until Elihu
Thomson, in the year 1886, developed the resistance welding technique.
Thomson technique
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This technique provided a more reliable and faster way of joining metal than
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did previous methods.
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As techniques were further developed, riveting was replaced in the United
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States and Europe by fusion welding to repair ships at the end of World War I.
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At that time the welding process was considered to be vital to military
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security. Repairs to the ships damaged during World War I were done in great
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secrecy. Even today some aspects of welding are closely guarded secrets.
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Since the end of World War I, many welding methods have been developed
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for joining metals. These various welding methods are playing an important
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role in the expansion and production of the welding industry. Welding has
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become a dependable, efficient, and economical method for joining metal.
WELDING DEFINED
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A weld is defined by the American Welding Society (AWS) as "a localized
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coalescence (the fusion or growing together of the grain structure of the
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materials being welded) of metals or nonmetals produced either by heating
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the materials to the required welding temperatures, with or without the
application of pressure, or by the application of pressure alone, and with or
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without the use of filler materials."
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Welding is defined as "a joining process that produces coalescence of
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materials by heating them to the welding temperature, with or without the
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application of pressure or by the application of pressure alone, and with or
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without the use of filler metal."
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In less technical language, a weld is made when separate pieces of
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material to be joined combine and form one piece when heated to a
temperature high enough to cause softening or melting and flow together.
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Pressure may or may not be used to force the pieces together. In some
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instances, pressure alone may be sufficient to force the separate pieces of
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material to combine and form one piece. Filler material is added when
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needed to form a completed weld in the joint.
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USES OF WELDING
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WELDING PROCESSES
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The number of different welding processes has grown in recent years.
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These processes differ greatly in the manner in which heat, pressure, or
both heat and pressure are applied, and in the type of equipment used.
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Figure 10.1 lists various welding methods. Certain methods listed in the
figure require hammering, pressing, or rolling to effect the coalescence in
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the weld joint. Other methods bring the metal to a fluid state, and the
edges flow together.
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The most popular processes are
Oxyacetylene welding (OAW),
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Shielded metal arc welding (SMAW)
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which often called stick welding,
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welding
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Gas tungsten arc welding (GTAW),
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Gas metal arc welding (GMAW),
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Flux cored arc welding (FCAW), and
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Submerge arc welding (SAW).
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Oxyacetylene is one part of the larger group of processes known as oxyfuel
gas (OF). This group of processes can be used for welding (OFW), cutting
(OFC), and brazing (TB). This group is one of the most versatile of the welding
processes. The equipment required is comparatively inexpensive, and the cost of
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operation is low, Figure 1-7.
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Shielded metal arc welding (SMAW) is the most common method of joining
metal. High-quality welds can be made rapidly and with excellent uniformity.
A variety of metal types and metal thicknesses can be joined with one machine,
Figure 1-8.
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Gas tungsten arc welding (GTAW) is easily performed on almost any
metal. Its clean, high-quality welds often require little or no postweld
finishing, Figure 1-9.
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Gas metal arc welding (GMAW) is extremely fast and
economical. This process is easily used for welding on
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thin-gauge metal as well as on heavy plate. The high
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welding rate and reduced postweld cleanup are making
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gas metal arc welding an outstanding welding process,
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Figure 1-10.
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Flux cored arc welding (FCAW) uses the same type of equipment that
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is used for the gas metal arc welding process. A major advantage of this
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process is that with the addition of flux to the center of the filler wire the
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weld's properties can be changed. Although welds must be cleaned after
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completion, the improved quality, flexibility, and welding speed offset this
requirement.
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Selection of the Joining Process
The selection of the joining process for a particular job depends upon many
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factors. No one specific rule controls the welding process to be selected
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for a certain job. A few of the factors that must be considered when
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choosing a joining process include:
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Availability of equipment - The types, capacity, and condition of
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equipment that can be used to make the welds.
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Repetitiveness of the operation - How many of the welds will be
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required to complete the job, and are they all the same?
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Quality requirements - Is this weld going to be used on a piece of
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furniture, to repair a piece of equipment, or to join a pipeline?
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Location of work - Will the weld be in a shop or on a remote job site?
Materials to be joined - Are the parts made out of a standard metal or
some exotic alloy?
Appearance of the finished product - Will this be a weldment that is
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only needed to test an idea, or will it be a permanent structure?
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Size of the parts to be joined - Are the parts small, large, or different
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sizes, and can they be moved or must they be welded in place?
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Time available for work - Is this a rush job needing a fast repair, or is
there time to allow for pre and postweld cleanup?
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Skill or experience of workers - Do the welders have the ability to do
the job?
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Cost of materials - Will the weldment be worth the expense of special
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equipment materials or finishing time?
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Code or specification requirements - Often the selection of the
process is dictated by the governing agency, codes, or standards.
The welding engineer and/or the welder must not only decide on the welding
process but must also select the method of applying it. The following
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methods are used to perform welding, cutting, or brazing operations.
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Manual - The welder is required to manipulate the entire process.
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Semiautomatic - The filler metal is added automatically, and all
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other manipulation is done manually by the welder.
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Machine - Operations are done mechanically under the observation
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and correction of a welding operator.
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Automatic - Operations are performed repeatedly by a machine that
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has been programmed to do an entire operation without interaction of
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the operator.
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Automated - Operations are performed repeatedly by a robot or
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other machine that is programmed flexibly to do a variety of
processes.
Welding Occupation
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Welder
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Welding foreman
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Welding supervisor
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Welding inspector B4T,Poltek,
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Lemigas, UI, Swasta
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Welding technician
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Welding instructor
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Welding engineer B4T, JWES,UI,
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Swasta
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Welding sales representative
Welding service representative
QUALIFICATION & CERTIFICATION
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Qualification
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is the ability of an individual to perform a job according to a
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required standard.
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Certification
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is a written statement attesting to the fact the welder has been
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able to produce welds meeting a prescribed standard.
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SHIELDED METAL ARC WELDING
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MANUAL METAL ARC WELDING
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STICK WELDING
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WELDING CURRENT
The welding current is an
electric current.
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An electric current is the flow
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of electrons.
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Electrons flow through a
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conductor from negative (-)
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to positive (+).
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Resistance to the flow of electrons (electricity) produces heat.
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The greater the resistance, the greater the heat.
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Air has a high resistance to current flow. As the electrons jump the air gap
between the end of the electrode and the work, a great deal of heat is produced.
Electrons flowing across an air gap produce an arc.
MEASUREMENT
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Voltage, or volts (V), is the
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measurement of electrical
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pressure.
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Voltage controls the maximum gap
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the electrons can jump to form the
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arc.
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Amperage, or amps (A), is the measurement of the total number of
electrons flowing.
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Amperage controls the size of the arc.
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Wattage is a measurement of the amount of power in the arc.
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The amount of power, watts, being put into a weld per cm controls the width and
depth of the weld bead.
TEMPERATURE
The temperature of a welding arc
exceeds 6000OC.
The exact temperature depends on the
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resistance to the current flow. The
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resistance is affected by the arc length
and the chemical composition of the
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gases formed as the electrode covering
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burns and vaporizes.
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As the arc lengthens, the resistance
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increases, thus causing a rise in the arc
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The shorter the arc, the lower the arc temperature produced.
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Most shielded metal arc welding electrodes have chemicals added to their
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coverings to stabilize the arc. These arc stabilizers reduce the arc resistance,
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making it easier to hold an arc. By lowering the resistance, the arc stabilizers also
lower the arc temperature. Other chemicals within the gaseous cloud around the
arc may raise or lower the resistance.
HEAT
The amount of heat produced is
determined by the size of the
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electrode and the amperage setting.
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Not all of the heat produced by an
arc reaches the weld. Some of the
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heat is radiated away.
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Heat also is lost through conduction
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in the work.
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In total, about 50% of all heat produced by an arc is missing from the weld.
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The 50% of the remaining heat the arc produced is not distributed evenly
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between both ends of the arc.
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This distribution depends on the composition and polarity of the electrode's
coating.
CURRENTS
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The three different types of current used for welding:
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1. Alternating current (AC)
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2. Direct-current electrode negative (DCEN)
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Direct-current straight polarity (DCSP)
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3. Direct-current electrode positive (DCEP)
Direct-current reverse polarity (DCRP)
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Each welding current has a different effect on the weld.
Direct-current electrode negative (DCEN)
Direct-current straight polarity (DCSP)
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In direct-current electrode negative, the electrode is negative, and the
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work is positive.
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DCEN welding current produces a high electrode melting rate.
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Direct-current electrode positive (DCEP)
Direct-current reverse polarity (DCRP)
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In direct-current electrode positive, the electrode is positive, and the
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work is negative.
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DCEP current produces the best welding arc characteristics.
Alternating current (AC)
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In alternating current, the electrons change direction every 1/120 of a second
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so that the electrode and work alternate from anode to cathode.
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The rapid reversal of the current flow causes the welding heat to be evenly
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distributed on both the work and the electrode; that is, half on the work
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and half on the electrode.
The even heating gives the weld bead a balance between penetration and
buildup.
TYPES OF WELDING POWER
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Constant Voltage (CV) - The arc voltage remains constant at the selected
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setting even if the amperage increases or decreases.
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Rising Arc Voltage (RAV) - The arc voltage increases as the amperage
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increases.
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Constant Current (CC) - The total welding current (watts) remains the
same. This type of power is also called Drooping Arc Voltage (DAV), or
droopers, because the arc voltage decreases as the amperage increases.
TYPES OF WELDING POWER
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TYPES OF WELDING POWER
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TYPES OF WELDING POWER
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TYPES OF WELDING POWER
The shielded arc process requires a constant current arc voltage
characteristic.
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This output power supply provides a reasonably high open circuit voltage
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before the arc is struck.
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The high open circuit voltage quickly stabilizes the arc.
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The arc voltage rapidly drops to the lower closed circuit level after the arc is
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struck.
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With a constant voltage output, small changes in arc length would cause the
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power (watts) to make large swings.
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The welder would lose control of the weld.
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OPEN CIRCUIT VOLTAGE
Open circuit voltage is the voltage at the electrode before striking an arc
(with no current being drawn).
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This voltage is usually between 50 V and 80 V.
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The higher the open circuit voltage, the easier it is to strike an arc.
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The higher voltage also increases the chance of electrical shock.
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CLOSED/OPERATING CIRCUIT VOLTAGE
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Operating voltage, or closed circuit voltage, is the voltage at the arc during
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welding.
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This voltage will vary with arc length, type of electrode being used, type of
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current, and polarity.
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The voltage will be between 17 V and 40 V.
ARC BLOW
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When electrons flow they create lines of magnetic
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force that circle around the line of flow.
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Lines of magnetic force are referred to as magnetic
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flux lines.
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The force that they place on the wire is usually small.
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However, when welding with very high amperages, 600 amperes or more, the
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force may cause the wire to move.
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A flowing current or residual magnetic field in a plate being welded will result in
uneven flux lines.
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These uneven flux lines can, in turn, cause an arc to move during a weld.
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This movement of the arc is called arc blow.
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Arc blow makes the arc drift like a string would drift in wind.
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Arc blow is more noticeable in corners, at the ends of plates, and when the work
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lead is connected to only one side of a plate.
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To control arc blow, the work lead is connected to the end of the weld joint, and
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weld should be made in the opposite direction, or two leads must be used, one
on each side of the weld.
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The best way to eliminate arc blow is to use alternating current.
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AC usually does not allow the flux lines to build.
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TYPES OF POWER SOURCES
A welding transformer uses the alternating current (AC) supplied to the welding
shop at high voltage to produce the low voltage welding power.
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Transformer
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Inverter
By using solid state electronic parts the incoming power in a inverter welder is
changed from 60 cycles a second to several thousand cycles a second (ACHF).
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This higher frequency allows the use of a transformer that may be as light as 7
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pounds and still do the work of a standard transformer weighing 100 pounds.
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Additional electronic parts remove the high
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frequency for the output welding power.
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The use of electronics in the inverter type
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welder allows it to produce any desired type of
welding power.
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Before the invention of this machine, each type
of welding required a separate machine.
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Now a single welding machine can produce the
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specific type of current needed.
Generator & Alternator
Generators and alternators both produce welding electricity from a mechanical
power source.
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In an alternator, magnetic lines of force rotate inside a coil of wire. An
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alternator can produce AC only.
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In a generator, a coil of wire rotates inside a magnetic force. A generator can
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produce AC or DC.
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It is possible for alternators and generators to both use diodes to change the
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AC to DC welding.
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Rectifier
Alternating welding current can be converted to direct current by using a series
of rectifiers.
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A rectifier allows current to flow in one direction only.
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DUTY CYCLE
Welding machines produce internal heat at the same time they produce the
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welding current.
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Except for automatic welding machines, welders are rarely used every minute
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for long periods of time.
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The welder must take time to change electrodes, change positions, or change
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parts. Shielded metal arc welding never continues for long periods of time.
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The duty cycle is the percentage of time a welding machine can be used
continuously.
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A 60% duty cycle means that out of every ten minutes, the machine
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can be used for six minutes at the maximum rated current.
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When providing power at this level, it must be cooled off for four minutes out
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of every ten minutes.
The duty cycle increases as the amperage is lowered and decreases for
higher amperages.
Most welding machines weld at a 60% rate or less.
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Therefore, most manufacturers list the amperage rating for a 60% duty cycle
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on the nameplate that is attached to the machine.
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Other duty cycles are given on a graph in the owner's manual.
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The following formula is for estimating the duty cycle at other than rated
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output and for estimating other than rated output current at a specified duty
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cycle:
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PROCESS
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SMAW
• Shielded metal arc welding uses the heat of an electric arc between a
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covered metal electrode and the work.
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• Shielding comes from the decomposition of the electrode flux coating.
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• Filler metal is supplied by the electrode core wire and covering.
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• This process is manually applied. The basic equipment is a power source,
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electrode cable, work cable, an electrode holder, a work clamp, and the
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electrode.
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Electrodes for SMAW operate variously on AC (alternating current), DCEP
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(reverse polarity), or DCEN (straight polarity).
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SMAW
• SMAW is the most widely used welding process because of its low cost,
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flexibility, portability, and versatility.
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• The SMAW process is very flexible in terms of the metal thicknesses that
can be welded and the variety of positions it can be used in.
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• Metal as thin as 2 mm thick to several feet thick can be welded using the
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same machine with different setting.
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• The flexibility of the process also allows metal in this thickness range to be
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welded in any position.
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SMAW is a very portable process because it is easy to move the equipment
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and engine-driven generator type welders are available.
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• The process is versatile, and it's used to weld almost any metal or alloy,
including cast iron, aluminum, stainless steel, and nickel.
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The electrode numbering for SMAW electrodes is shown below:
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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COVERED ELECTRODES
a
• A shielded metal arc weld is strengthened by adding alloying elements to
aj
the electrode covering.
dm
• Unfortunately, some ingredients and the binder in the covering can attract
A
and hold moisture (a source of hydrogen), which can cause cracking in
wi
certain metals.
D
• A group of electrodes specifically formulated to result in weld deposits
a
having very low levels of hydrogen are referred to as low hydrogen.
tr
•
Pu
Electrodes that are classified as low hydrogen have identification numbers
ending with 5, 6, or 8.
la
da
an
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M
an
da
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Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
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Pu
tr
a
D
wi
A
dm
aj
a
The electrode coating provides the following:
1. Arc stabilization from ionizing elements (which dictate the usability of
a
the electrode on AC, DCEP, or DCEN).
aj
dm
2. Gas shielding for the weld puddle when some of the coating breaks
down.
A
3. Slagging agents contained in the coating that remove impurities from
wi
the work surface and weld puddle.
D
4. Deoxidizers, contained in the coating that reduce the tendency for
a
tr
porosity in the weld.
Pu
5. An insulating blanket formed by the slag that protects the cooling weld
la
metal from the atmosphere.
da
6. Alloying elements contained in the coating that strengthen the weld
an
metal.
M
7. Increased weld metal deposition, when iron powder is incorporated
in the coating.
ADVANTAGES:
a
1. Low initial investment cost
aj
dm
2. Simple and operationally reliable
A
3. Low cost filler materials
wi
4. Wide range of filler materials
D
5. Same equipment for all materials
a
tr
6. Spans a large thickness range
7. All welding positions Pu
la
da
an
M
DISADVANTAGES:
a
aj
1. Slow (changing electrodes)
dm
2. A layer of solidified slag must be removed
A
wi
3. Low-hydrogen electrodes require special storage
D
4. Low deposition efficiency
a
tr
Pu
la
da
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M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
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an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
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an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
a
aj
dm
GAS METAL ARC WELDING
A
wi
D
METAL INERT GAS
a
tr
METAL ACTIVE GAS
Pu
la
da
an
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INTRODUCTION
• GMAW uses the heat of an electric arc between a
continuous bare wire filler metal electrode and the
a
work.
aj
dm
• Shielding is obtained entirely from externally supplied inert
A
gas such as argon or helium, an active gas such as CO2 or
wi
O2, or some combination thereof.
D
a
• GMAW can be a semiautomatic, machine, automatic, or
tr
automated process.
Pu
la
• In the semiautomatic mode, the welder controls both the
da
inclination and distance of the welding gun from the work,
an
and also the travel speed and manipulation of the arc.
M
• Arc length and electrode feed are controlled automatically
by the power source and wire feeder controller.
PROCESS
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
EQUIPMENT
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
GMA SPOT WELDING
tr
a
D
wi
A
dm
aj
a
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DEFINITION
an
da
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Pu
tr
a
D
wi
A
dm
aj
a
METAL TRANSFER MODES
The gas metal arc process deposits the weld metal in the joint by
a
one of the following modes:
aj
dm
1. Spray transfer
A
2. Globular transfer
wi
D
3. Short circuiting transfer
a
tr
4. Pulsed arc transfer
Pu
la
da
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M
an
da
la
Pu
tr
a
D
wi
METAL TRANSFER MODES
A
dm
aj
a
Spray Arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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Spray Arc Metal Transfer
a
aj
• This process is identified by the pointing of the wire tip from which very
dm
small drops are projected axially across the arc gap to the molten weld pool.
A
• There are hundreds of drops per second crossing from the wire to the
wi
base metal.
D
• These drops are propelled by arc forces at high velocity in the direction the
a
wire is pointing.
tr
Pu
• Since the drops are separated and directed at the molten weld pool, the
process is spatter free.
la
da
• Spray transfer process requires three conditions: argon shielding (or argon-
rich shielding gas mixtures), DCEP polarity, and a current level above a critical
an
amount called the transition current.
M
Spray Arc Metal Transfer
• Spray transfer occurs when the transition current and
voltage exceed a level that depends upon the type and
a
aj
size of the wire.
dm
• For each electrode size and type, there is a transition
A
current above which the metal "pinches off" in fine
wi
droplets many times per second.
D
a
• Spray transfer mode best defines the arc and the pool for
tr
the welder. Pu
la
• Spray transfer mode requires high current relative to the
da
diameter of the electrode.
an
M
• Due to its high heat capacity, this mode of transfer is best
suited for flat and horizontal position welding.
Spray Arc Metal Transfer
a
The transition current
aj
dm
depends on the alloy
being welded.
A
wi
It also is proportional
D
to the wire diameter,
a
tr
meaning that higher
Pu currents are needed
la
with larger diameter
da
wires.
an
M
Spray Arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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Globular Arc Metal Transfer
• Globular transfer occurs at low currents compared to
spray transfer-low, that is, in relation to the size of the
a
aj
electrode.
dm
• Low-current density at the electrode tip produces large,
A
irregular drops of metal that transfer to the pool without
wi
much direction.
D
a
• The result is increased amounts of spatter, as
tr
Pu
compared to spray transfer.
la
• The large drops are partially supported by arc forces.
da
an
• As they become heavy enough to overcome those forces
M
and drop into the pool, they bridge the gap between the
wire and the weld pool, producing explosive short
circuits and spatter (Figure 10-7).
Globular Arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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Globular Arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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Globular Arc Metal Transfer
• Carbon dioxide was one of the first gases studied during the
development of the GMAW process.
a
• It was abandoned temporarily because of excessive spatter
aj
dm
and porosity in the weld.
A
• After argon was accepted for shielding, further work with
wi
carbon dioxide demonstrated that the spatter was associated
D
with globular metal transfer.
a
tr
• Additional work showed that the arc in carbon dioxide was very
forceful.
Pu
la
da
• Because of this, the wire tip could be driven below the surface
an
of the molten weld pool.
M
• With the shorter arcs, the drop size is reduced, and any spatter
produced as the result of short circuits was trapped in the
cavity produced by the arc.
Globular Arc Metal Transfer
• Hence, the name buried-are transfer, Figure 10-8
(the tip of the electrode is actually below the
a
aj
surface of the work, in order to minimize spatter)
dm
• The resultant welds tend to be more highly crowned
A
wi
than those produced with open arcs, but they are
D
relatively free of spatter and offer a decided
a
advantage of welding speed.
tr
Pu
• These characteristics make the buried-arc process useful
la
for high-speed mechanized welding of thin sections,
da
such as that found in compressor domes for
an
hermetic air-conditioning and refrigeration equipment or
M
for automotive components.
Globular Arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
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da
an
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Globular Arc Metal Transfer
a
• Because carbon dioxide is an oxidizing gas, its applications
aj
to welding carbon steels are restricted.
dm
A
• It cannot be used to fabricate most nonferrous materials.
wi
• Neither should it be used to weld stainless steels because
D
carbon corrodes the weld metal.
a
tr
Pu
• Carbon dioxide and helium are similar in that metal
transfer in both gases is globular.
la
da
• Helium has the advantage of inertness, potentially making
an
it useful for the same types of applications as carbon
M
dioxide but in nonferrous alloys.
Short-circuiting Arc Metal Transfer
• Low currents allow the liquid metal at the electrode tip to
be transferred by direct contact with the molten weld pool.
a
A close interaction between the wire feeder and the power
aj
dm
supply is required. This technique is called the short-
circuiting transfer.
transfer
A
wi
• Current continues to flow and the resistance causes the
D
wire to separate and the arc to reignite, which causes
a
tr
the weld to be deposited drop by drop up to 200 drops
per second. Pu
la
da
• The short circuiting mode is a relatively cold process, and
an
its misapplication can result in incomplete fusion.
M
• It readily bridges gaps.
• Sheet metal can be welded without excessive melt-
through and welds may be made in all positions.
positions
Short-circuiting Arc Metal Transfer
The transfer mechanisms in this process are quite simple
and straight forward, as shown schematically below:
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Short-circuiting Arc Metal Transfer
• To start, the wire is in direct contact with the molten weld pool
(Figure 10- 9a). The power supply senses a low-voltage short circuit and
a
responds by increasing the current.
aj
dm
• As the current increases, the interface between the wire and molten
weld pool is heated until it vaporizes (Figure 10-9b), establishing an
A
arc. The relatively high current of that arc produces sufficient force to
wi
depress the molten weld pool.
D
a
• A gap between the electrode tip and the molten weld pool (Figure 10-
tr
9c) immediately opens. Sensing the higher voltage, the current output
from the Pu
power supply begins to decay.
la
• When the arc force at a lower current is insufficient to keep the
da
molten weld pool depressed (Figure 10-9d), contact is reestablished
an
(Figure 10-9a).
M
• The liquid formed at the wire tip during the arc-on interval is
transferred by surface tension to the molten weld pool, and the
cycle begins again with another short circuit.
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Short-circuiting Arc Metal Transfer
• If the system is properly tuned, the rate of short circuiting can reach
a
hundreds per second, causing a characteristic buzzing sound.
aj
dm
• The spatter is low and the process easy to use.
A
• Carbon dioxide works well with this short-circuiting process because
wi
it produces the forceful arc needed during the arcing interval to displace
D
the weld pool.
a
• Helium can be used as well.
tr
Pu
• Pure argon is not as effective because its arc tends to be sluggish.
la
• However, a mixture of 25% carbon dioxide and 75% argon produces
da
a less harsh arc and a flatter, more desirable weld profile. Although
an
more costly, this gas mixture is preferred.
M
Short-circuiting Arc Metal Transfer
• Small wire diameters are preferred even though more
a
aj
expensive.
dm
• This process works better with a short electrode stickout.
A
wi
• Although very useful for welding sheet steel, the short-
D
circuiting process does not produce enough heat to make
a
tr
quality welds in sections much thicker than 1/4 in. (6 mm).
Pu
• Lack-of fusion defects can occur unless the process is
la
perfectly tuned and the welder is highly skilled.
da
an
M
M
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da
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Pu
tr
a
D
wi
A
dm
aj
a
DCRP
Pulsed-arc Metal Transfer
• Pulsed arc welding maintains a low voltage and current arc as the
a
background condition.
aj
dm
• This condition causes an arc to maintained, but does not cause metal
transfer.
A
wi
• The power supply can be adjusted to provide a pulse of high current
D
and voltage, which takes the welding conditions above the transition
a
level and detaches a drop from the electrode and propels it across the
tr
arc.
Pu
• The number of pulses per second can usually be adjusted; transfer
la
occurs during each pulse.
da
an
• Pulsing the power lowers the average heat input from the current, and
M
out-of- position welding then becomes possible using larger wire sizes.
• The power supply must have pulsing capabilities.
Pulsed-arc Metal Transfer
• The average current can be reduced sufficiently to reduce penetration
enough to weld sheet metal or reduce deposition rates enough to
a
aj
control the molten weld pool in all positions.
dm
• This level controlling the weld heat input and rate of weld metal
A
deposit is achieved by changing the following variables:
wi
Frequency - The number of times the current is raised
D
and lowered to form a single pulse.
a
tr
Frequency is measured in pulses per
second.
Pu
la
Amplitude - The amperage or current level of the
da
power at the peak or maximum, expressed in
an
amperage.
M
Width of the pulses - The amount of time the peak amperage is
allowed to stay on, Figure 10-5.
Pulsed-arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
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Pulsed-arc Metal Transfer
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Pulsed-arc Metal Transfer
• This technology did not receive much attention until solid-state
electronics (inverter) were developed to handle the high power
a
required of welding power supplies.
aj
dm
• Solid-state electronics provided a better, simpler, and a more
economical way to control the pulsing process.
A
wi
• The newest generation of pulsed-arc systems interlocks the power
D
supply and wire feeder so that the proper settings of the wire feed
a
end power supply are obtained for any given job by adjusting a single
tr
knob.
Pu
• Such systems have been termed synergic. In some respects, these
la
systems are more complex because the correct interrelationships
da
between the wire feed speeds and power supply settings must be
an
programmed into the equipment, and each wire composition, wire
M
size, and shielding gas requires a special program.
• The manufacturer generally programs the most common
combinations, allowing space in-the computer for additional user
input.
Shielding Gases
• The primary function of the shielding gas is to exclude the
atmosphere from contact with the molten weld metal.
a
aj
• This is necessary because most metals, when heated to
dm
their melting point in air, exhibit a strong tendency to
A
form oxides and, to a lesser extent, nitrides.
wi
D
• Oxygen will also react with carbon in molten steel to form
a
carbon monoxide and carbon dioxide.
tr
Pu
• These varied reaction products may result in weld
la
deficiencies, such as trapped slag, porosity and weld
da
metal embrittlement.
an
M
• Reaction products are easily formed in the atmosphere
unless precautions are taken to exclude nitrogen and
oxygen.
Shielding Gases
a
aj
In addition to providing a protective environment, the shielding gas and
dm
flow rate also have a pronounced effect on the following:
A
wi
• Arc characteristics
D
• Mode of metal transfer
a
• Penetration and weld bead profile
tr
• Speed of welding
•
Pu
Undercutting tendency
la
da
• Cleaning action
an
• Weld metal mechanical properties
M
M
an
Shielding Gases
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
Shielding Gases
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
Shielding Gases
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
Shielding Gases
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Cleaning Action
• The cathodic cleaning action associated with argon at DCRP is very
a
important for fabricating metals such as aluminum, which quickly develops
aluminum
aj
undesirable surface oxides when exposed to air.
dm
• This same cleaning action causes problems with steels.
steels
A
• Iron oxide in and on the steel surface is a good emitter of electrons that
wi
attracts the arc cathode.
D
• But these oxides are not uniformly distributed, resulting in very irregular
a
tr
cathode movement and in turn irregular weld deposits.
Pu
• This problem was solved by adding small amounts of oxygen to the argon.
la
• The reaction produced a uniform film of iron oxide on the weld pool and
da
provided a stable site for the cathode.
an
• This discovery enabled uniform welds in ferrous alloys and expanded the
M
use of GMAW to welding those materials.
Cleaning Action
• The amount of oxygen needed to stabilize arcs in steel
varies with the alloy.
a
aj
dm
• Generally, 2% is sufficient for carbon and low-alloy
steels.
A
wi
• In the case of stainless steels, about 0.5% should
D
prevent a refractory scale of chromium oxide.
a
tr
• Carbon dioxide can substitute for oxygen.
Pu
la
• More than 2% is needed, however, and 8% appears to
da
be optimum for low-alloy steels.
an
M
• In many applications, carbon dioxide is the preferred
addition because the weld bead has a better contour
and the arc appears to be more stable.
Solid Electrode Wire
a
aj
dm
A
wi
D
a
tr
"E" denotes an electrode;
electrode
Pu
la
"R" denotes a rod (round) electrode.
da
The next two digits (three in a 5-digit number) stand for the tensile strength of
an
the weld deposit, times 1000.
M
"S" denotes a solid electrode.
The last digit is the chemical classification.
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Advantages
• Can be effectively used to join or overlay many types of ferrous and
a
nonferrous metals.
aj
dm
• Gas shielding can reduce the possibility of hydrogen being introduced into the
weld zone.
A
• High deposition rate compared to SMAW.
wi
D
• High efficiency and utilization of filler material because the continuous spool
of wire does not require changing as often as the individual electrodes used in
a
tr
SMAW.
Pu
• Due to the lack of a slag coating that must be removed after welding, GMAW
la
is well suited for automatic and robotic welding or high production.
da
• GMAW is a clean process, because there is no flux present. When no slag is
an
present, the welder can more easily observe the action of the arc and the
M
weld puddle to improve control.
• Extremely versatile, wide and broad application ability.
Disadvantages
• Since GMAW uses shielding gas alone to protect the puddle from the
a
atmosphere excessive contamination of the base metal may cause porosity.
aj
dm
• Drafts or wind may disperse shielding gases, which makes GMAW
unsuitable for field welding.
A
wi
• The equipment used is more complex than that used for SMAW, increasing
the possibility of mechanical problems that can lead to quality problems.
D
a
• Higher-price equipment.
tr
• The use of short-circuiting transfer can lead to lack of fusion discontinuities.
Pu
• Inability to reach inaccessible welding areas.
la
da
• Limited distance.
an
• Inability to push small diameter, soft electrode through long cable.
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
a
aj
dm
A
GAS TUNGSTEN ARC WELDING
wi
D
TUNGSTEN INERT GAS
a
tr
Pu
la
da
an
M
INTRODUCTION
The aircraft industry developed the GTAW process for welding
a
magnesium during the late 1930s and the early 1940s. During that time,
aj
helium was the primary shielding gas used, along with DCEP welding
dm
current. These caused many problems that limited application of the GTA
A
welding process. But improvements in gas composition and a better
understanding of the importance of polarity improved the process’s
wi
effectiveness and reduced its cost.
D
a
Before development of GTAW process, welding aluminum and magnesium
tr
was difficult. The welds produced were porous and corrosion-prone.
Pu
la
da
Until the late 1940s, GTAW was the only acceptable process for welding
such reactive materials as aluminum, magnesium, titanium and some
an
grades of stainless steel regardless of thickness.
M
INTRODUCTION
GTAW uses an electric arc between a non-consumable tungsten
electrode and the work. Shielding is obtained from an inert gas or inert
a
aj
gas mixture. Filler metal can be added as needed. The torch is usually
dm
water cooled, but can be air cooled for low-current applications.
A
This type of welding can be accomplished by manual, mechanized, or
wi
automatic methods. When filler metal is added, the process calls for a
D
two-handed technique, as in oxyacetylene welding. Cold-wire and
technique
a
hot-wire feeds are automated versions of that technique.
tr
Pu
Slow heating and low temperatures combined with the slow
la
cooling rates that are characteristic of GTAW result in improved weld
da
metal and heat-affected zone (HAZ) mechanical properties. The tungsten
electrode provides the means of initiating the arc. The melting is
an
essentially slow and that most of the gases evolved can escape from the
M
weld pool before it freezes.
INTRODUCTION
For mechanized applications, filler wire may be added manually or by
a
aj
the use of a wire feeder.
dm
The classification for filler wire for GTAW operations is the same as that
A
for the GMAW process.
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
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aj
a
NON-CONSUMMABLE TUNGSTEN ELECTRODE
Tungsten, atomic symbol W, has the following properties:
Tungsten
a
• High tensile strength, 3,447 kg/mm2
aj
• Hardness, Rockwell C 45
dm
• High melting temperature, 3,410oC
• High boiling temperature, 5,630oC
A
• Good electrical conductor
wi
D
Tungsten is produced mainly by reduction of its trioxide with hydrogen.
a
Powdered tungsten is then purified to 99.95+%, compressed, and sintered
tr
(heated to a temperature below melting where grain growth can occur) to
Pu
make an ingot. The ingot is heated to increase ductility and then is swaged
la
and drawn through dies to produce electrodes.
da
These electrodes are available in sizes varying from 0.25 mm to 6 mm in
an
diameter. The tungsten electrode, after drawing, has a heavy black oxide
M
that is later chemically cleaned or ground off.
NON-CONSUMMABLE TUNGSTEN ELECTRODE
The high melting temperature and good electrical conductivity make
a
tungsten the best choice for a non-consumable electrode. The arc
aj
temperature, around 6,000oC, is much higher than the melting temperature
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of tungsten but not much higher than its boiling temperature of 5,900oC.
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The thermal conductivity of tungsten and the heat input are prime factors in
D
the use of tungsten as an electrode.
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NON-CONSUMMABLE TUNGSTEN ELECTRODE
Tungsten is a good conductor of heat. This conductive property is what
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allows the tungsten electrode to withstand the arc temperature well above
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its melting temperature.
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The heat of the arc is conducted away from the electrode's end so fast that
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it does not reach its melting temperature.
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For example, a wooden match burns at approximately 1,647oC. Because
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aluminum melts at 971oC, a match should easily melt an aluminum wire.
Pu
However, a match will not even melt a 2-mm aluminum wire. The
aluminum, like a tungsten electrode, conducts the heat away so quickly that
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it will not melt.
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NON-CONSUMMABLE TUNGSTEN ELECTRODE
a
As the tungsten electrode becomes hot the arc between the electrode and
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the work will stabilize.
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A
Because electrons are more freely emitted from a hot tungsten, the very
highest temperatures possible at the tungsten electrode tip is desired.
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Maintaining a balance between the heat required to have a stable arc and
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that high enough to melt the tungsten requires an understanding of the
GTA torch and electrode.
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NON-CONSUMMABLE TUNGSTEN ELECTRODE
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GTAW TORCH COOLING SYSTEM
The torch end of the electrode is tightly clamped in a collet.
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The collet inside the torch is cooled by air or water.
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The collet is the cone-shaped sleeve that holds the electrode in the torch.
A
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Heat from both the arc and the tungsten electrode's resistance to the flow
of current must be absorbed by the collet and torch.
D
a
To ensure that the electrode is being cooled properly, be sure the collet
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connection is clean and tight.
Pu
And for water-cooled torches, make sure water flow is adequate.
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Large-diameter electrodes conduct more current because the resistance
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heating effects are reduced. However, excessively large sizes may result in
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too low a temperature for a stable arc.
GTAW TORCH COOLING SYSTEM
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GTAW TORCH COOLING SYSTEM
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GTAW TORCH COOLING SYSTEM
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ELECTRODE TIP SHAPE
The current-carrying capacity at DCEN is about ten times greater than that
a
at DCEP.
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The preferred electrode tip shape impacts the temperature and erosion of
A
the tungsten.
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With DCEN, a pointed tip concentrates the arc as much as possible and
D
improves arc starting with either a short, high-voltage electrical discharge
a
or a touch start.
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Pu
Because DCEN does not put much heat on the tip, it is relatively cool,
la
the point is stable, and it can survive extensive use without damage, Figure
da
14-4A.
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ELECTRODE TIP SHAPE
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a
ELECTRODE TIP SHAPE
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With alternating current (AC), the tip is subjected to more heat than with
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DCEN. To allow a larger mass at the tip to withstand the higher heat the
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tip is rounded. The melted end must be small to ensure the best arc
A
stability, Figure 144B.
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DCEP has the highest heat input to the electrode tip. For this reason
D
a slight ball of molten tungsten is suspended at the end of a
a
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tapered electrode tip. The larger mass of the tungsten above the molten
ball holds it in place like a drop of water on your fingertip, Figure 144C.
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TYPES OF WELDING CURRENTS
All three types of welding current can be used for GTA welding. Each
a
current has individual features that make it more desirable for specific
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conditions or with certain types of metals.
dm
The major differences among the currents are in their heat distributions and
A
the presence or degree of arc cleaning. Figure 14-28 shows the heat
wi
distribution for each of the three types of currents.
D
Direct-current electrode negative (DCEN), concentrates about two-
a
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thirds of its welding heat on the work and the remaining one-third on the
tungsten. The higher heat input to the weld results in deep penetration.
penetration
Pu
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The low heat input into the tungsten means that a smaller sized tungsten
da
can be used without erosion problems.
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The smaller sized electrode may not require pointing, resulting in a savings
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of time, money, and tungsten.
TYPES OF WELDING CURRENTS
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TYPES OF WELDING CURRENTS
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TYPES OF WELDING CURRENTS
Direct-current electrode positive (DCEP), concentrates only one-
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third of the arc heat on the plate and two-thirds of the heat on the
electrode.
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A
This type of current produces wide welds with shallow penetration,
penetration
but it has a strong cleaning action.
action
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D
The high heat input to the tungsten indicates that a large-sized tungsten
a
is required, and the end shape with a ball must be used.
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Pu
The low heat input to the metal and the strong cleaning action on the
metal make this a good current for thin, heavily oxidized metals.
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The metal being welded will not emit electrons as freely as tungsten, so
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the arc may wander or be more erratic than DCEN.
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TYPES OF WELDING CURRENTS
There are many theories as to why DCEP has a cleaning action.
a
aj
The most probable explanation is that the electrons accelerated from the
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cathode surface lift the oxides that interfere with their movement.
A
The positive ions accelerated to the metal's surface provide additional
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energy.
D
In combination, the electrons and ions cause the surface erosion needed to
a
produce the cleaning.
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Pu
Although this theory is disputed, it is important to note that DCEP occurs,
that it requires argon-rich shield gases and DCEP polarity, and that it can
la
be used to advantage, Figure 14-29.
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TYPES OF WELDING CURRENTS
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TYPES OF WELDING CURRENTS
Alternating current (AC) concentrates about half of its heat on the work
a
aj
and the other half on the tungsten.
dm
Alternating current is DCEN half of the time and DCEP the other half of the
A
time.
wi
The frequency at which the current cycles is the rate at which it makes a
D
full change in direction, Figure 14-30.
a
tr
In America, the current cycles at the rate of 60 times per second or 60
hertz (60 Hz).
Pu
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Alternating current high-frequency stabilized, or ACHF is used to
da
ease arc starting due to low voltage from welding machine that may be
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insufficient to initiate electron flow.
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CLEANING ACTION
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GTA WELDING ON ALUMINUM
With the exception of aluminum, which is normally welded using AC, most
a
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of the GTAW is done using DCEP.
dm
Aluminum forms an oxide immediately upon being cleaned.
A
Oxide cleaning occurs when using DCEP or AC, however, DCEP is
wi
impractical due to the electrode's poor current-carrying capacity, but AC
D
provides cleaning every half cycle.
a
tr
Arc re-ignition is normally accomplished by a superimposed high-frequency
Pu
current (ACHF) (see Table 10.2).
la
Although the electrode is called non-consumable, it does become
da
contaminated by contact with the weld puddle or the filler metal, and
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becomes consumed as it is cleaned, leads to TUNGSTEN CONTAMINA-
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TION.
TUNGSTEN CONTAMINATION
The most frequently occurring and most time-consuming problem in GTAW
a
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is tungsten contamination.
dm
The tungsten becomes contaminated when it touches the molten weld pool
A
or when it is touched by the filler metal.
wi
When this happens, especially with aluminum, surface tension pulls the
D
contamination up onto the hot tungsten, Figure 15-8.
a
tr
The extreme heat causes some of the metal to vaporize and form a large,
Pu
widely scattered oxide layer.
la
On aluminum, this layer is black. On iron (steel and stainless steel), this
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layer is a reddish color.
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TUNGSTEN CONTAMINATION
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TUNGSTEN CONTAMINATION
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SHIELDING GAS
The shielding gases used for the GTA welding process are argon (Ar),
a
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helium (He), hydrogen (H), nitrogen (N), or a mixture of two or
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more of these gases.
A
The purpose of the shielding gas is to protect the molten weld pool and the
wi
tungsten electrode from the harmful effects of air.
D
The shielding gas also affects the amount of heat produced by the arc and
a
the resulting weld bead appearance.
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Pu
Argon and helium are noble inert gases. This means that they will not
combine chemically with any other material.
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Argon and helium may be found in mixtures but never as compounds.
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Because they are inert, they will not affect the molten weld pool in any
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way.
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SHIELDING GAS
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BACKING GAS
Root contamination caused by the surrounding atmosphere is not a major
problem when welding on mild steel pipe.
a
aj
Some type of protection, however, is needed when welding on low-alloy
dm
steel, stainless steel, aluminum, copper, and most other types of pipe.
A
The easiest method of protecting the root from atmospheric contamination
wi
is to use a backing gas. The gas is used to purge the root area from the air.
D
The type of gas used for backing will depend upon the type of pipe being
a
welded.
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Pu
Argon and helium are satisfactory for the backup purge when welding all
materials.
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da
Nitrogen may be used satisfactorily for backing up welds in austenitic
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stainless steel, copper, and copper alloys.
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CO2 are often acceptable, depending upon the code or intended use of the
pipe system.
BACKING GAS
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BACKING GAS
There are several methods in common use for containing the backing gas in
a
the pipe.
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On small diameters or short sections of pipe, the ends of the pipe are
capped, Figure 16-12. The gas is allowed to purge the complete pipe
A
section. This method requires too much purging time and gas to be practical
wi
on large-diameter pipe.
D
For larger diameters, the pipe is plugged on both sides of the joint to be
a
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welded so that a smaller area can be purged. If the piping system is
Pu
complex, consisting of valves and numerous turns, water-soluble plugs or
soft plastic gas bags are suggested. They can be blown out with air or water
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when the system is completed.
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BACKING GAS
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BACKING GAS
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BACKING GAS
When a backing gas is used, the gas must have enough time to purge the
pipe completely. The joint is taped over to prevent the gas from being
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aj
blown out too fast. This will allow a slower flow rate to be used on the
dm
purging gas. The tape is removed just ahead of the weld, Figure 16-13.
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FILLER METALS SPECIFICATION
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FILLER METALS SPECIFICATION
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ADVANTAGES
• The GTAW process is capable of welding virtually all metals, even
a
extremely thin materials.
aj
dm
• The principal advantage of GTAW is that high-quality welds with
excellent visual appearance can be produced.
A
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• Because no flux is used, the process is quite clean and there is no
slag to remove after welding.
D
a
• Little/no spatter.
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Pu
• Arc and weld pool are clearly visible to the welder.
la
• All positions.
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• Cleaning action with DCEP and AC.
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DISADVANTAGES
• The skill level necessary to produce high-quality welds is acquired only
a
after much experience in manipulating the electrode and feeding the filler
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wire.
dm
• Because the process has a low tolerance for contamination, the base and
A
filler metals must be extremely clean prior to welding.
wi
• GTAW is among the slowest of the available welding processes.
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a
• Low productivity.
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• Higher initial cost.
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FLUX-CORED ARC WELDING
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PRINCIPLES OF OPERATION
FCAW uses the heat of an arc between a continuous filler metal electrode
a
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and the work, which is similar to GMAW, except that in FCAW the
dm
electrode is tubular and contains a granular flux instead of the solid wire
used in GMAW.
A
wi
Shielding is obtained, in whole or in part, from a flux contained within the
tubular electrode.
D
a
The flux inside the electrode provides the molten weld pool with protection
tr
from the atmosphere, improves strengths through chemical reactions and
Pu
alloys, and improves the weld shape.
la
Self-shielded electrodes require no external gas protection, while other
da
flux cored electrodes use additional external gas shielding supplied through
an
the welding gun.
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PRINCIPLES OF OPERATION
a
If external shielding is provided, the choice of shielding gas is usually
aj
carbon dioxide, argon, or a mix of carbon dioxide and argon.
dm
Thus, 75% argon - 25% carbon dioxide can be used to improve the
A
operating characteristics of the arc and provide excellent mechanical
wi
properties of the finished weld.
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PRINCIPLES OF OPERATION
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Strength and other physical or corrosive properties of the finished weld are
dm
improved by the flux.
A
Small additions of alloying elements, deoxidizers, and slag agents all can
wi
improve the desired weld properties.
D
Carbon, chromium, and vanadium can be added to improve hardness,
a
strength, creep resistance, and corrosion resistance.
tr
Pu
Aluminum, silicon, and titanium all help remove oxidizes and/or nitrides in
the weld.
la
da
Potassium, sodium, and zirconium are added to form slag.
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PRINCIPLES OF OPERATION
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PRINCIPLES OF OPERATION
A slag covering of the weld is useful for several reasons.
a
aj
Slag helps the weld by protecting the hot metal from the effects of the
dm
atmosphere, controlling the bead shape by serving as a dam or mold, and
serving as a blanket to slow the weld's cooling rate, which improves its
A
physical properties.
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PRINCIPLES OF OPERATION
a
Similar to GMAW, FCAW uses constant voltage (CV) type power supply.
aj
dm
CV power supplies provide a controlled voltage (potential) to the welding
electrode. The amperage (current) varies with the speed that the electrode
A
is being fed into the molten weld pool.
wi
D
Just like GMA welding, higher electrode feed speeds produce higher
a
currents and slower feed speeds result in lower currents, assuming all other
tr
conditions remain constant.
Pu
The effects on the weld of electrode extension, gun angle, welding
la
direction, travel speed, and other welder manipulations are similar to those
da
experienced in GMA welding.
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PRINCIPLES OF OPERATION
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PRINCIPLES OF OPERATION
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PRINCIPLES OF OPERATION
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ELECTRODES
The electrodes have flux tightly packed inside. One method used to make
a
them is to first form a thin sheet of metal into a U-shape. Then a measured
aj
quantity of flux is poured into the U-shape before it is squeezed shut. It is
dm
then passed through a series of dies to size it and further compact the flux.
A
wi
A second method of manufacturing the electrode is to start with a seamless
D
tube. The tube is usually about 1 inch in diameter. One end of the tube is
a
sealed, and the flux powder is poured into the open end. The tube is vibrated
tr
during the filling process to insure that it fills completely. Once the tube is full,
Pu
the open end is sealed. The tube is now sized using a series of dies.
la
da
In both these methods of manufacturing the electrode, the sheet and tube are
an
made up of the desired alloy. Also in both cases the flux is compacted inside
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the metal skin. This compacting helps make the electrode operate smoother
and more consistently.
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ELECTRODES
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ELECTRODES
Electrodes are currently available in sizes from 0.8 mm to 3.9 mm in
diameter. Smaller diameter electrodes are much more expensive per
kg than the same type in a larger diameter. Larger diameter electrodes
a
produce such large welds they cannot be controlled in all positions. The most
aj
popular diameters range from 1.2 mm. to 2.3 mm.
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FLUX
a
• The fluxes used are mainly RUTILE or LIME based.
aj
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• The purpose of the fluxes is the same as in the SMAW process, that is, they
provide deoxidizers, slag formers, arc stabilizers, alloying elements, and a
A
shielding gas.
wi
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• The RUTILE-BASED (RB) system produce a fine drop transfer, a
a
relatively low fume, and an easily removed slag.
tr
•
Pu
The LIME-BASED (LB) are associated with a more globular transfer, more
spatter, more fume, and a more adherent slag. These characteristics are
la
tolerated when it is necessary to deposit very tough weld metal and for
da
welding materials having a low tolerance for hydrogen.
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FLUX
• Care must be taken to use the cored electrodes with the recommended
a
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gases or not to use gas at all with the self-shielded electrodes.
dm
• Using a self-shielding, flux-cored electrode with a shielding gas
may produce a defective weld.
A
wi
• The shielding gas will prevent the proper disintegration of much of the
D
deoxidizers.
a
• This results in the transfer of these materials across the arc to the weld.
tr
•
Pu
In high concentrations, the deoxidizers can produce slag that become
trapped in the welds, causing undesirable defects. Lower concentrations
la
may cause brittleness only.
da
• In either case, the chance of weld failure is increased.
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• If these electrodes are used correctly, there is no problem.
FLUX
a
• Some fluxes can be used on both single and multiple pass welds, and
aj
others are limited to single pass welds only.
dm
• Using a single pass welding electrode for multipass welds may result in an
A
excessive amount of manganese.
wi
• The manganese is necessary to retain strength when making large, single
D
pass welds.
a
tr
• However, with the lower dilution associated with multipass techniques, it
Pu
can strengthen the weld metal too much and reduce its ductility.
la
• In some cases, small welds that deeply penetrate the base metal can help
da
control this problem.
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FLUX
• The welding position can also be influenced by the flux composition.
a
• Some electrodes are limited in their out-of-position welding ability. Still
aj
others can be used in all positions.
dm
• The use of the correct shielding gas or gas mixture improves some of the
A
out-of-position capabilities of electrodes.
wi
• Table 12-1 lists the shielding and polarity for the flux classifications of mild
D
steel FCAW electrodes.
a
tr
• The letter G is used to indicate an unspecified classification. The G means
Pu
that the electrode has not been classified by the American Welding Society.
la
• Often the exact composition of fluxes are kept as a manufacturer's trade
da
secret.
an
• Therefore, only limited information about the electrode's composition will
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be given.
• The only information often supplied is current, type of shielding required,
and some strength characteristics.
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FLUX
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ELECTRODES DESIGNATION
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"E" denotes electrode.
electrode
tr
Pu
The next digit is the tensile strength of the weld deposit times 10 000.
la
The next digit is the position the electrode can be used in.
da
"1" can be used in all positions.
positions
an
"0" can be used flat and horizontal only.
only
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"T" denotes a tubular wire.
wire
The last digit is the chemical classification.
classification
ADVANTAGES
a
aj
• High Deposition Rate (more than 12 kg/hr compared to SMAW, 6 kg/hr
dm
with 6 mm electrode diameter).
A
• Minimum Electrode Waste (high electrode metal utilization)
wi
The FCA method makes efficient use of filler metal; from 75% to 90% of the
D
weight of the FCA electrode is metal, the remainder being flux. SMA
a
electrodes have a maximum of 75% filler metal; some SMA electrodes have
tr
much less. Also a stub must be left at the end of each SMA welding
Pu
electrode. The stub will average 2 in. (51 mm) in length, resulting in a loss of
la
11 % or more of the SMAW filler electrode purchased. FCA welding has no
da
stub loss, so nearly 100% of the FCAW electrode purchased is used.
an
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• FCAW is characterized by an aggressive, deeply penetrating arc that tends
to reduce the possibility of fusion-type discontinuities.
ADVANTAGES
• Less Edge Preparation
Because of the deep penetration characteristic, no edge beveling
a
aj
preparation is required on some joints in metal up to 13 mm in thickness.
dm
When bevels are cut, the joint included angle can be reduced to as small as
35o. The reduced groove angle results in a smaller sized weld. This can save
A
50% of filler metal with about the same savings in time and weld power
wi
used.
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ADVANTAGES
• Less precleaning required than GMAW
The addition of deoxidizers and other fluxing agents permits high-quality
a
aj
welds to be made on plates with light surface oxides and mill scale. This
dm
eliminates most of the precleaning required before GMA welding could be
performed. Often it's possible to make excellent welds on plates in the "as
A
cut" condition; no cleanup needed.
wi
D
• All Position
a
Small diameter electrode sizes in combination with special fluxes allow
tr
excellent welds in all positions. The slags produced assist in supporting the
Pu
weld metal. This process is easy to use, and, when properly adjusted, it is
much easier to use than other all-position arc welding processes.
la
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• Flexibility – welds a variety of steels over a wide thickness range
an
Changes in power settings can permit welding to be made on thin-gauge sheet
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metals or thicker plates using the same electrode size. Multipass welds allow
joining unlimited thickness metals. This, too, is attainable with one size of
electrode.
ADVANTAGES
• High-quality weld metal deposit
a
Many codes permit welds to be made using FCAW. The addition of the flux
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gives the process the high level of reliability needed for welding on boilers,
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pressure vessels, or structural steel.
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• Excellent control & excellent weld appearance
The molten weld pool is more easily controlled with FCAW than with GMAW.
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The surface appearance is smooth and uniform even with less operator skill.
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Visibility is improved by removing the nozzle when using self-shielded
electrodes.
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• FCAW can be used in both shop and field applications.
applications
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LIMITATIONS
• The main limitation of flux cored arc welding is that it is confined to
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ferrous metals and nickel based alloys. Generally, all low- and medium-
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carbon steels, some low-alloy steels, cast irons, and a limited number of
stainless steels are presently weldable using FCAW.
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• The equipment and electrodes used for the FCAW process are more
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expensive. However, the cost is quickly recoverable through higher
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productivity.
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• Pu
The removal of postweld slag requires another production step. The flux
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must be removed before the weldment is finished (painted) to prevent
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crevice corrosion.
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• The flux also generates a significant amount of smoke, which reduces the
welder's visibility and makes the weld puddle more difficult to observe.
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AUTOMATIC FCAW
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AUTOMATIC FCAW
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AUTOMATIC FCAW
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AUTOMATIC FCAW - SURFACING
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SUBMERGED ARC WELDING
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DESCRIPTION OF THE PROCESS
SUBMERGED ARC WELDING (SAW) produces coalescence of metals by
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heating them with an arc between a bare metal electrode and the work.
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The arc and molten metal are "submerged" in a thick blanket of
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granular fusible flux on the work.
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Pressure is not used, and filler metal is obtained from the electrode and
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sometimes from a supplemental source such as welding rod or metal
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granules.
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Welding under a granular flux is a semiautomatic, mechanized or automatic
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process in which electrode feed and arc length are controlled by the wire
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feeder and power supply.
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In automatic welding, a travel mechanism moves either the torch or the
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work, and a flux recovery system recirculates the unfused granular flux back
to the flux hopper for reuse.
DESCRIPTION OF THE PROCESS
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DESCRIPTION OF THE PROCESS
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DESCRIPTION OF THE PROCESS
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DESCRIPTION OF THE PROCESS
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In submerged arc welding, the arc is covered by a flux.
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This flux plays a main role in that:
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(1) the stability of the arc is dependent on the flux,
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(2) mechanical and chemical properties of the final weld deposit
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can be controlled by flux, and
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(3) the quality of the weld may be affected by the care and handling of
the flux.
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WELD TRAVEL
The arc is hidden in submerged arc welding, which frees the welder or
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operator from his helmet but hides the path he must follow.
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Movement along a joint can be provided manually or mechanically.
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Hand-held travel can be a welder manually moving the gun at a constant
speed along the joint, or there might be a small gun-mounted motor and
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friction drive wheel to provide a more consistent travel rate.
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Work travel can be provided using rollers or other types of positioners. In
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some cases a positioner may be used in unison with some type of gun
travel. Pu
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These systems lend themselves to computer controlled automation.
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WELD TRAVEL
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HAND-HELD SAW
Hand-held SAW is increasing in usage for a variety of reasons.
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One of the most significant is that there are little if any fumes or smoke to
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exhaust.
exhaust
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New local, state, and federal laws have put restrictions on the material that can
A
be free-vented in to the atmosphere. There are requirements in some locations
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that require the welding shop ventilation systems to have collectors and
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filtration equipment in operation.
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This process does not eliminate all fumes and smoke, but the reduction can
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significantly reduce the shop's ventilation costs. A shop using SAW is a
costs
much cleaner place to work. Pu
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The arc light and spatter are blanketed by the flux covering so the
welding technicians can wear lighter protective clothing. This reduces welder
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fatigue and increases productivity.
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HAND-HELD SAW
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HAND-HELD SAW
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ELECTRODE FEED
SAW electrode feed systems are similar to all of the other CV processes.
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The filler metal is provided on spools, coils, or in bulk drums. The feed system
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consists of a variable speed drive motor, motor controller, and drive rollers. The
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drive rollers are usually the knurled V-groove type, although sometimes the
smooth V-groove type rollers are used. The filler metal is fed at a
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constant rate to the arc.
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The CV power provides the arc current to melt the wire at a rate
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matching the fed rate. The electrode melts and is transferred across the arc to
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the work through the molten pool or flux.
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The flux reacts with the metal both during the arc and within the molten weld
pool. Weld cooling is somewhat slowed by the heat retaining blanket
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provided by the slag.
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If the cooling rate is too fast in large welds, some impurities can be
trapped in the center of the weld nugget.
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The rate of cooling can be slowed if preheat and postheat are used.
ELECTRODE
SAW filler metals are available in both the standard wire and several special
forms.
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The wire comes in sizes from 1.6 mm to 6 mm.
mm
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Twisted wire is used to give the arc some oscillating movement as the
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wire enters the weld, Figure 13-8. This oscillation helps fuse the toe of the weld
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to the base metal.
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Strip electrodes are used for surfacing applications. The strips are
applications
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available up to 76 mm wide and in several thicknesses.
thicknesses
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ELECTRODE
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ELECTRODE
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ELECTRODE
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FLUX
The weld composition results from contributions from the melted base metal
and the electrode, modified by chemical reactions with the flux, and alloys
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added through the flux.
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Fluxes are classified according to the mechanical properties of the weld metal
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deposited. The same chemically composed flux can have many different
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classifications, depending upon the classifications of the electrode it is used with
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and the condition of heat treatment given the weld for testing.
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Since the flux and filler wire are independently dispensed in this process, great
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flexibility in obtaining weld properties is possible.
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Shop dirt, grease or moisture can contaminate the flux, resulting in cracks.
cracks
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Some fluxes require heated storage containers and hoppers to ensure that
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the flux is dry when used.
Unmelted flux can still be recycled.
FLUX TYPES
Fluxes are grouped into three types according to their method of
manufacture: fused, bonded, and mechanically mixed.
fused bonded mixed
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Fused fluxes are mixtures that have been heated until they melt into a solid
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metallic glass. They are then cooled and ground into the desired granular size
range. Fused fluxes cannot be alloyed because they are a form of glass and
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all components in that glass are essentially oxides. They will not dissolve metals
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without reacting with them, thereby reducing their effectiveness as alloying
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materials.
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Bonded fluxes are a mixture of fine particles of fluxing agents, deoxidizers,
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alloying elements, metal compounds, and a suitable binder that holds the
mixture together in small, hard granules. Each granule is composed of all the
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ingredients in the correct proportions.
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Mechanically mixed fluxes are mixtures of fused and bonded fluxes, or a fine
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mixture of agents in a desired proportion for a certain job.
FLUX STORAGE
To prevent contamination of the weld by hydrogen, the flux must be kept dry
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and free from oils or other hydrocarbons.
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If flux becomes damp, it must be redried.
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Excessive levels of hydrogen in some steels can cause porosity.
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In hardenable steels, even small amounts of hydrogen can cause underbead
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cracking.
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Commercially available dryers are the best method of drying flux.
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Do not dry flux by using a direct flame.
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This may fuse the flux together; and, at the same time, the flame produces
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water that might condense on the flux.
ELECTRODE & FLUX CLASSIFICATION
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•
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Electrode classifications are prefixed with the letter E, designating an
electrode.
electrode
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• The next letter L (low), M (medium), or H (high) refers to the range of
manganese.
manganese
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• The next one or two digits indicate the normal carbon point of the wire.
One carbon point equals 0.01% carbon.
• The last letter is K and may or may not be used. When it is used, it means
the electrode was drawn from a silicon-killed steel.
steel
ELECTRODE & FLUX CLASSIFICATION
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ELECTRODE & FLUX CLASSIFICATION
• The basic flux classification is prefixed with the letter F, which designates it
as a flux.
flux
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• This is followed by one digit, which represents 10,000 psi (69 MPa)
digit
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minimum tensile strength of the weld.
weld
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• The digit is followed by the letter A or P.
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The A means the weld was tested and classified in the "as-welded
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condition."
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The P means the weld was tested and classified after the prescribed amount
of post-weld heat treatment.
treatment
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• The next item in the classification is a single digit or the letter K. The digit
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indicates the lowest temperature, in -10oF (-23oC) units, that the weld
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metal will meet or exceed the required 20 foot-pound (27 J) impact
strength test.
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• The letter K indicates that no impact strength test is required.
required
ELECTRODE & FLUX CLASSIFICATION
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WELD BACKING
Because the welds made with SAW are usually very large, it's often necessary to
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support the root face of the weld.
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The support can be provided by placing something under the joint, such as a
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strip of copper, a trough filled with flux, or a backing weld.
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ARC STARTING
There are six commonly used methods of starting the arc:
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• Steel wool ball starting
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A small ball of steel wool is placed between the electrode and the work before
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the flux is added. The welding current causes the steel wool ball to quickly
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heat up, and the arc is started.
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ARC STARTING
• High-frequency starting
A high-frequency current is sent through the electrode, and it establishes the
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arc when the welding power is turned on.
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• Scratch starting
The electrode is dragged along the joint before the welding current is started.
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When the welding current makes contact with the moving base metal, it
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begins to spark, which starts the arc.
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• Wire retract start
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The wire is advanced until it touches the base metal and the welding current
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is applied. At that moment the electrode is withdrawn slightly to start the arc.
• Sharp wire start Pu
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If the end of the wire is cut to a point, that point will quickly arc when it
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contacts the base metal.
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• Molten flux start
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The arc will restart on its own if the electrode is lowered into a pool of molten
slag and the welding power is restarted.
ADVANTAGES
• Highest deposition rate & speed
Using large-diameter wires, more than 18 kg/hr can be deposited. This rate
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is nearly two times the rate of FCAW and four times that of SMAW.
SMAW
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• High utilization of electrode wire
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With SAW, there is no spatter to waste metal and cause cleanup
problems. All of the electrode is transferred and becomes weld deposit. Only
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the melted flux needed for the weld is lost. Unfused granular flux can be
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retrieved and reused. The amount of flux consumed can be controlled by
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varying the arc length, which is done by changing the arc voltage.
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• Weld size
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Flat groove or fillet welds as thick as 25 mm can be made in one pass using
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a single electrode. Larger sizes are possible with multiple electrodes. SAW has
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very deep penetrating capabilities.
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• High-quality welds, smooth, uniform finished weld
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Many codes permit SAW to be used on structural iron, pressure vessels,
cryogenic cylinders, and in many other critical applications.
ADVANTAGES
• Easily adapted
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With this process, the flux and wire are purchased separately. The flux can be
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used to change the alloys in the weld metal deposited from the electrode. By
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changing the flux, the properties of the weld are altered. The composition of
the flux is easily changed to meet specific metallurgical properties. Two or
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more fluxes can be mixed, or granulated metal can be added to a flux or
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mixture to meet individual needs.
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• SAW can be performed on numerous metals.
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• Minimum operator protection required
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Because of the lack of an arc, the operator has no need for a filter lens and
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other heavy protective clothing. Another benefit is that there is less smoke
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generated than with the other processes.
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• Submerged arc welding is a versatile production welding process
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capable of making welds with currents up to 2000 amperes, AC or DC,
amperes
using single or multiple wires or strips of filler metal. Both AC and DC
power sources may be used on the same weld at the same time.
DISADVANTAGES
• Restricted to flat position and horizontal fillets.
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• Welding parameters need careful control
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Because the arc flux hides the weld pool, welding conditions must be preset
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on the basis of experiments or with proven tabular information, including the
contact tip-to-work distance, the current, the travel speed, and the voltage.
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Arc voltage must be carefully controlled to ensure the proper weld profile.
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Equally important, deviations in arc voltage can cause significant changes in
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the weld composition when using the fluxes as the source of alloys.
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• Cleaning the work surfaces and aligning the machine travel with the
joint are particularly important. Improper alignment will result in offset
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beads with incomplete joint penetration. In a highly restrained joint, joint
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misalignment may also cause cracks.
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• The flux is of a low-hydrogen type that may require storage in
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heated ovens.
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• Because of its deep penetrating arc it may have an extreme width to depth
ratio, that can lead to centerline cracking.
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APPLICATION
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APPLICATION
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APPLICATION
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Welding Inspection
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Ir.Soeweify, M.Eng
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Head of Strength and Structure Groups
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Department of Shipbuilding Engineering
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Surabaya Institute of Technology
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Welding Engineer 1980 Hiroshima University
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Welding Inspector 1984 Hamburg University
Fracture Mechanic 1990 Bandung Institute of Technology
Welding Occupation
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Welder ( Tack Welder, 1G- 6GR )
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Welding foreman
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Welding supervisor
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Welding technician
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Welding sales representative
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Welding service representative
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Welding instructor
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Welding inspector ( our goal )
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Welding engineer
Course contains of WI
• Qualification for welding inspector
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– Module1 Welding Inspection Technology
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• Standard including Codes and specification
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– Module 2 Welding Inspection Technology
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• Weld geometry and Welding terminology
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– Module 3 Welding Inspection Technology
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• Welding and NDT symbol
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– Module 5 Welding Inspection Technology
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• Welding procedures and welder Qualification
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– Module 8 Welding Inspection Technology
Why the weld product must be
inspected
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• Weld product almost have the defect.
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– Metallurgical defect
– Dimensional defect
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• Weld product have Stress Concentration Factor
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– Stress raiser cause of Kt
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– Initiation of crack at the stress riser
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• Weld product consist of Heat affected zone
( HAZ )
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– Big grain size, hydrogen diff, low strength.
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• Weld metal have low fatigue strength
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– High SCF and low fracture toughness
Defect of Welding
• Metallurgical defect
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Defect of Welding
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Dimensional defect
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Stress Concentration Factor
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• Maximum Stress
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Effect of Stress Concentration
factor on fatigue strength
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Smooth specimen
have higher
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fatigue limit,
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More higher stress
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concentration
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factor have affect
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fatigue life of
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material
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V notch have
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lower fatigue
strength
Heat Affected Zone
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• Big grain size
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Why the weld product must be
inspected ( Continued )
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• Weld product almost have Residual stress
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– Lower fatigue strength
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– Deformation
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• Weld product is Brittle material, martensit
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– Crack easy to propagate,
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– Easy to fracture
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• Weld product need NDT and DT
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– Need inspector, need welding inspector
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• Weld product depend on welder, machine,
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material and method process
– Need Qualifications such as WPQ, WQT,WPS,PQR
Influence of Residual stress
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Comparation between fatigue
Strength of base and welded metal
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Fatigue life of weld metals are more lower than
fatigue life of base metal because of Kt and Residual Stress
Brittle material of weld metal
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• Start from liquid than
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be a austenit and
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depend on the
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cooling rate
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Austenit become
– Martensite Pu
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– Bainite
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– Ferrite
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– Perlite
Martensite is brittle so the material is easy to fracture
DT used in testing
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• Destructive test
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– Tension test ( Obliged )
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– Bending test ( Obliged )
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– Fracture test ( Obliged )
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– Macro and Micro test ( Optional )
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– Metallurgical test ( Optional )
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– Hardness test ( Optional )
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– Fatigue Test ( Optional )
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– Fracture toughness test ( Optional )
NDT used in testing
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• Non Destructive Test
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– Visual inspection ( Obliged )
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– Dye Penetrant test ( Optional )
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– Magna Flux test ( Optional )
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– Ultra sonic Test ( Optional, Obliged )
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– Radiography test ( Obliged )
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Therefore need WPQ, WQT,WPS,PQR
and finally need Welding Inspector
Terminologies
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• WQT : Welder Qualification test
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– Welder only
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• WPQ : Welding Prosedure Qualification
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– Welder, Material, Machine, Procedure
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• WPS : Welding Procedures Spesification
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– Spesification procedure for test spesimens
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• PQR : Procedures Qualification Record
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– Record of accepted WPS
Qualification of Welding Inspector
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• Physical condition
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– Active and good physical condition
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– Climbing , come down to the double bottom, etc
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• Good vision
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– Ability to examine weld surface, film X ray
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– To determine and enforce any color perception
requirement Pu
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• Professional attitude
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– Remain in partial and consistent in all decision
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• Knowledge of welding and inspection
terminology
– Standard welding term and definition A.3.0
Qualification of W.I ( cont )
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• Knowledge of drawing and specifications
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– Not necessary to memorize all standard and
specification but know how to get.
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• Ability to produce and maintain records
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– Record of inspection, PQR
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• Knowledge of welding process
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– SMAW, GMAW, GTAW, FCAW, SAW
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• Ability to be trained
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– To improve the competency
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• Inspection Experiences
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– On the job training in welding problem
Lines of comunication of WI
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Standard Code for Welding
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• The Structural Welding Code AWS D11
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– Radiology Section VI Part B
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– Ultra Sonic Section VI Part C
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– Magnetic particle ASTM E 709
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– Dye Penetrant ASTM E 165
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– Design New Bridge AWS D11 Sec IX
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– Tubular structure AWS D11 Sec X
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– AWS D1.2 Alluminium. D1.3 Sheet steel
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– AWS D1.4 Reinforcing steel
Standard Code for Welding cont
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• ASME Boiler and Pressure Vessel
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– I. Power Boiler
A
– II. Material spesification
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• Part A Ferrous Material
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• Part B Non Ferrous Material
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• Part C Welding Rod, Electrode and Filler Metal
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– III. Nuclear Component for power plan
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– IV. Heating Boiler
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– V. Non Destructive Examination
Standard Code for Welding cont
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• ASME Boiler and Pressure Vessel
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– VI. Recomended Rules for Care and
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Operation of Heating Boiler
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– VII. Recomended Rules for care of Power
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Boiler
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– VIII. Pressure Vessel
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– IX. Welding and Brazing Qualification
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– X. Fibreglass - Reinforced Plastic Vessel
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– XI.Rule for Inservice Inspection of Nuclear
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Power Plan Components
Standard Code for Welding cont
a
• API Standard 1104 Standard for Welding
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Pipeline and Related Facilities
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– Qualification for welding procedures
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– Welder qualification
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– Design and preparation of joint for production
welding Pu
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– Inspection and testing of production welding
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– Standard of acceptability Non Destructive
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Testing
Standard Material Specification
a
• ASTM A 36 Specification for structural Steel
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• ASTM A 53 Spec for Welded and Seamless
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steel pipe
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• ASTM A 242 Spec for High strength low alloy
D
• ASTM A 501 Spec for Hot formed Welded and
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Seamless Carbon steel structural Tubing
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• ASTM A 570 Spec for Hot rolled Carbon steel
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sheet and strip structural qyality
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• ASTM A 709 Specification for structural steel for
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bridge
Standard Material Specification
a
• ASTM A 285 Spec for low and intermediate
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Tensile strength Carbon steel plate for Pressure
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Vessel
A
• ASTM A 209 Spec for Seamless Carbon
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Molybdenum Alloy steel Boiler, superheater
D
a
• ASTM A 213 Spec for Seamless Ferrite and
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Austenite Alloy steel Boiler, Superheater and
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heat exchanger tubes
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• API standard 5 L spec for pipe line
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• API standard 5LX high test pipeline
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• API standard 5LS spiral weld pipe
Standard Code for Welding Electr
• A.5.1 Spec for mild steel Covered Arc Welding
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Electrodes
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• A.5.5 Spec for Low Alloy steel Covered Arc Welding
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Electrodes
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• A.5.4 Spec for Corrosion Resisting Chromium and
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Chromium Nickel steel Covered Arc Welding Electrodes
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• A.5.2 Spec for Iron and steel Gas Welding rod
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• A.5.23 Spec for Bare low alloy steel electrode and flux for
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SAW
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• A.5.28 Spec for Bare low alloy steel filler metal for
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GMAW
• A. 5.14 Spec for Nickel and Nickel Alloy Bare welding
rods and electrode
Fundamental of Visual Inspection
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• Prior to Welding
aj
dm
– Review Drawing and specification
A
– Check WPQ and personil WQT to be utilized
wi
D
– Establish check point
a
– Set up a plan for recording the results
tr
Pu
– Review material to be utilized
la
– Check base metal discontinueities
da
an
– Check fit up and alignment
M
– Check pre heat temperature if required
Fundamental of Visual Inspection cont
a
• Joint Fit up
aj
dm
– Check groove angle 55º
A
– Root opening
wi
– Joint alignment
D
a
– Backing material, steel, ceramic, cuprum, glass wool
tr
–
Pu
Consumable insert ( to be used )
la
– Joint cleanlines
da
– Tack weld
an
– Pre heating temperatur
M
Fundamental of Visual Inspection cont
a
• During the welding
aj
dm
– Welding Machine , Parameter Voltage, Amperage,
A
Duty cycle
wi
– Electrode, filler metal, fluks, shielding gas
D
– Pre heating and temperatur interpass
a
tr
– Cleanlines inter pass
Pu
– Gauging and grinding
la
da
– Back weld
an
– Welding squence
M
– PWHT
Fundamental of Visual Inspection cont
a
• After welding
aj
dm
– Weld appearance
A
– Joint dimention, deformation
wi
D
– Surface weld defect
a
tr
• Under cut
• Overlap Pu
la
da
• Under fill
an
• Excessive reinforcement
M
• Creater crack, crack
• Spatter
Peralatan bantu Pemeriksaan
visual
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Standard acceptable weld profile
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Inspection Responsibilities of WI
Before Welding
• Review all applicable drawing and
a
aj
standard
dm
A
– Construction profile, material plate, profile etc
wi
– Detail drawing, shop drawing
D
a
• Check purchase order to ensure that base
tr
Pu
metal and filler material are properly
la
specified
da
an
– Welding material , plates, profiles, electrodes,
M
fluxes, etc
– Mill certificat, Batch number
Inspection Responsibilities of WI
Before Welding
a
• Check and identity material as they are received
aj
dm
against the purchase specification.
A
– Steel, electrode, flux, etc
wi
– Mill certificate, Defect, Lamination, dented
D
a
• Check chemical composition and mechanical
tr
Pu
properties shown on mill test report against
specified requirements.
la
da
– Retest if necessary
an
– Comply to the specification
M
Inspection Responsibilities of WI
Before Welding ( cont )
a
• Check the condition and storage of filler
aj
dm
metals.
A
– Low hydrogen need special treatment.
wi
D
• Check the condition and adequacy of
a
tr
equipment to be used.
Pu
– Amperage and duty cycle, grounded
la
da
• Check weld joint edge geometries
an
M
– Root gap, joint configuration.
Inspection Responsibilities of WI
Before Welding ( cont )
a
• Check joint fit
aj
dm
– No misalignmen, Root Gap,
A
– Good edge preparation
wi
D
• Check of joint cleanness
a
tr
– No greese, water, etc
Pu
la
• Check the WPQ and WQT as well as PQR
da
an
• Check pre heat temperature
M
– Specially for problem steel
Inspection Responsibilities of WI
During Welding
a
• Check welding parameters and techniques for
aj
dm
compli-ance with welding procedure.
A
– Amperage, speed, polarization,
wi
• Check inter pass cleaning and inter pass
D
temperature.
a
tr
– Interpass temp 200º C
Pu
– Slag must be removed and weld bead must be
la
cleaned by wire brush.
da
• Verify that in-process non-destructive
an
examination (NDE) is performed, if required.
M
– Type of NDT, place, and number of test
Inspection Responsibilities of WI
After Welding
a
• Check finished weld appearance weld
aj
dm
sizes and lengths.
A
– Bead appearance, leg length, height of bead.
wi
D
• Check dimensional accuracy of completed
a
tr
weldment
Pu
– Check the deformation after welding
la
da
• Select production test samples.
an
M
– Select the bad one , the difficult one
Inspection Responsibilities of WI
After Welding
a
• Evaluate test results.
aj
dm
– Evaluate to compliance the standard
A
requirement.
wi
D
• Verify that additional NDE has been
a
tr
performed, if re-quired.
Pu
• Prepare and maintain inspection reports.
la
da
– Check list report
an
M
– Daily, monthly report.
Welding Procedures Specification
a
• WPS adalah prosedure pengelasan tertulis
aj
yang telah di kualifikasi yang digunakan
dm
untuk memberikan arahan pada juru las dan
A
wi
operator mesin las agar hasil production
D
welding memenuhi persyaratan yang
a
tr
ditentukan oleh code and standard.
Pu
• WPS berisi semua variable ( essential , non
la
da
essential and supplementary essensial )
an
yang digunakan dalam proses pengelasan
M
dan harus mengacu pada PQR yang sudah
ada.
Welding Procedures Specification
a
• Perubahan non essensial untuk menyesuaikan
aj
dengan persyaratan produksi tanpa dikualifikasi
dm
ulang tetapi harus dicatat
A
• Perubahan essensial dan suplementar harus
wi
dilakukan kualifikasi ulang .
D
a
• PQR adalah rekaman yang berisi
tr
– semua data variabel pengelasan yang digunakan
Pu
untuk mengelas test coupon
la
– Hasil pengujian test piece yang dibuat dari test
da
coupon tersebut
an
– Varabel pada PQR digunakan didalam production
M
welding
Essential and non essential
a
• Joints, Materials
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Essential and non essential
a
• Filler metals, Positions, Pre heat
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Essential and non essential
a
• PWHT, Electrical characteristic, Technic
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Code, Standards and Specification
a
• Code is a set of rule of procedures and standards of
aj
material designed to secure uniformity and to protect
dm
public interest in such matters as building construction
A
and public health, established usually by public agency
wi
• Standards is Some thing that is established by authority,
D
costum,or general consent as a model or example to be
a
tr
followed.
Pu
• Spesification is a detail, precise, explicit presentation
la
( as by number, description, or working drawing ) of
da
some thing or a plan or proposal of something
an
• Code Standard and specification
M
• AWS D11 by Society, Standard by Authority such as SNI
Welding Procedures Specification
• Item yang umum di dalam WPS
a
aj
– Scope proses pengelasan , jenis material,
dm
spesifikasi yang diminta
A
wi
– Base metal spesifikasi,
D
• Identifikasi base metal baik melalui komposisi kimia
a
maupun sifat mekanik atau mengacu pada material
tr
tertentu dan
Pu
• Apabila base metal mensyaratkan perlakuan khusus
la
da
sebelum pengelasan harus dinyatakan dengan jelas
an
(normalizing, annealing, quenching, tempering )
M
• Ketebalan base metal mempengaruhi laju
pendinginan sehingga perlu di tulis dan biasanya
dalam range
Welding Procedures Specification
a
• Item yang umum di dalam WPS
aj
dm
– Welding process
A
• Welding process yang digunakan harus
wi
dinyatakan dalam WPS
D
– Type of filler metal
a
tr
• Type dan clasifikasi dan composition dari filler
Pu
metal chemical composition dan pabrik
la
– Type of current
da
an
• Range ampere dan jenis apa DC atau AC juga
M
disebutkan polaritasnya
Welding Procedures Specification
a
aj
• Item yang harus ada didalam WPS
dm
– Arc voltage and travel speed
A
wi
• Arc and travel speed harus disebutkan rangenya
D
apalagi pada pengelasan otomatis atau heat input
a
sangat berpengaruh
tr
Pu
– Joint design and tolerance
la
• Harus digambar beserta toleransinya
da
– Joint preparation and cleaning of surface
an
M
• Harus disebutkan methode yang digunakan untuk
persiapan dan pembersihan permukaan yang akan
dilas
Welding Procedures Specification
a
– Tack Welding
aj
dm
• Apabila tack welding dianggap mempengarui
A
kekuatan perlu disebutkan
wi
– Joint welding design
D
a
• Detail ukuran electroda untuk tiap lapis pengisian,
tr
range arus dsbnya.
Pu
– Position of welding
la
da
• Kualitas pengelasan juga tergantung posisi oleh
an
sebab itu posisi saat pengelasan harus disebutkan
M
Welding Procedures Specification
• Item yang harus ada di dalam WPS
a
aj
Pre heat and interpass temp
dm
• Pada material tertentu harus dilakukan Pre heating
A
Temp, tempat, dan cara pemanasan harus
wi
disebutkan
D
– Root preparation prior to welding from second
a
tr
side
Pu
• Apabila dilakukan gouging disebutkan alatnya dan
la
kedalaman gouging
da
an
– Peening
M
• Tidak boleh berlebihan akan tetapi bila dikerjakan
dengan baik memberikan pengurangan Residual
stress perlu disebutkan alat yang digunakan
Welding Procedures Specification
a
• Item yang umum di dalam WPS
aj
dm
– Remofal of weld section of repair
A
• Apabila ada perbaikan dengan cara
wi
D
menghilangkan weld metal perlu dijelaskan
a
– Post weld heat treatment
tr
Pu
• Apabila struktur memerlukan perlakuan panas
la
perlu disebutkan cara dan waktu serta
da
temperaturnyadiperlukan
an
M
Welding Procedures Specification
a
aj
– Arc voltage and travel speed
dm
A
• Harus sesuai dengan yang ada di PQR
wi
– Joint design and tolerance
D
• Sesuai dengan detail drawing
a
tr
– Joint preparation
Pu
la
• Persiapan sisi harus bersih ,baik, sesuai standard
da
an
M
Welding Procedures Qualification
a
• Tujuan
aj
dm
– Mendemontrasikan bahwa material dan metoda yang
disebutkan dalam WPS akan mengghasilkan sifat
A
mekanis sambungan las yang memenuhi spesifikasi
wi
dan aplikasi yang disyaratkan.
D
a
• Tahapan
tr
Pu
– Persiapan dan pengelasan sample
la
– Pengujian spesimen yang mewakili
da
– Evaluasi semua tahapan mulai persiapan
an
pengelasan, pengujian dan hasil akhir
M
– Persetujuan apabila hasil sesuai standar
Tahapan WPQ
a
• Persiapan
aj
dm
– Pembuatan test piece untuk pembuatan test
A
coupon pengujian
wi
– Butt joint uji tarik dan bending
D
a
– Fillet joint uji fracture
tr
• Pengujian Pu
la
– Pengujian sesuai dengan code yang
da
digunakan
an
M
– Mulai Visual, Uji merusak, uji tak merusak
Tahapan WPQ
a
• Evaluasi
aj
dm
– Evaluasi hasil pengujian sesuai persyaratan
A
standar
wi
• Persetujuan
D
a
– Pihak ketiga atau independen memberikan
tr
Pu
persetujuan hasil kualifikasi
la
– WPS yang sudah lolos uji kualifikasi Qualified
da
WPS
an
– Bersama dokumen lain disimpan disebut
M
PQR
Squence of WPQ through Actual
Testing
a
• Select welding variable
aj
dm
• Check equipmentand material for suitable
A
wi
• Monitor weld joint fit up as well as actual
D
welding, and recording all importance
a
tr
variable and observation
Pu
la
• Select , identity and remove test specimen
da
an
• Test and evaluate specimen
M
Squence of WPQ through Actual
Testing
a
• Review test result for compliancr with applicable
aj
dm
code requirement
A
• Release approve procedures for production
wi
D
• Qualify individual welder in accordance this
a
procedures
tr
Pu
• The welding inspector must than monitor the use
la
of that procedures during production to assure
da
that it continues to produce satisfactory results
an
M
Persyaratan codes dan standards
untuk uji kualifikasi WPS
a
• AWS D11
aj
dm
– Pengelasan berbagai komponen struktur seperti
jembatan, bangunan,struktur tubular
A
– Konsep prequalified weld joint
wi
– Selama pelaksanaan pengelasan sesuai dengan
D
persyaratan desain dan workmanship dan code tidak
a
tr
perlu kualifikasi aktual.
Pu
la
• API standard 1104 Standard for Welding
da
Pipeline and Related Fasilities
an
– Pipe line dan petroleum equipment
M
– Seperti ASME setiap ada perubahan pada prosedur
mensyarakan pengujian kualifikasi aktual
Persyaratan codes dan standards
untuk uji kualifikasi WPS
a
• ASME Boiler and Pressure Vessel Code Section
aj
dm
IX
A
– Bejana tekan, boiler.
wi
– Pengelasan harus mengacu pada prosedur yang
D
telah di kualifikasikan
a
tr
– Pipa bertekanan ASME B31 ( Code for pressure
Pu
piping ) juga menggunakan code ini
la
da
– ASME selalu mensyaratkan mengerjakan kualifikasi
an
prosedur
M
– Dokumen WPS dan PQR yang telah terkualifikasi
Procedure Qualification Record
a
• Rekaman tertulis mengenai data pengelasan
aj
dm
yang digunakan untuk mengelas test coupon
A
• Data variabel pengelasan dan hasil pengujian
wi
mekanis serta radiografi
D
a
• Production welding harus mengacu pada PQR
tr
Pu
• PQR harus mendokumen semua variabel
la
esensial dan bila disyaratkan variabel suplemen
da
juga didokumen dan merupakan suatu rentang
an
M
misal dari sekian sampai sekian
Welder Performance &
Qualification Test ( WPQT )
a
• Juru las dan operator perlu dikualifikasi untuk melihat
aj
kemampuan mereka menghasilkan sambungan yang
dm
mulus ( sound ) dan acceptable dengan memakai
A
proses, material, dan teknik yang telah didifinisikan
wi
dalam WPS yang terkualifikasi
D
• Kualifikasi personil tanggung jawab perusahaan
a
tr
• Manufacturer,contractor, fabricator,erector dan owner
Pu
juga bertanggung jawab untuk kualitas hasil las
la
• Program jaminan mutu harus dibuat
da
• Jenis pengujian sebagian besar code, standard, dan
an
spesification hampir sama untuk aplikasi pengelasan
M
pelat bagian struktur, pipa,dan sheet
Uji Ulang ( Retest )
a
• Dilakukan apabila
aj
dm
– Juru las atau operator mesin las gagal pada uji
pengelasan test coupon
A
wi
– Terdapat perubahan mendasar ( essential and
D
supplementary essential )
a
– Tidak lagi mengelas dalam waktu tertentu ( 6 bln )
tr
Pu
– Ada alasan yang jelas untuk meragukan kemampuan
juru las
la
da
• Retest visual, mekanis, radiography
an
– Masing masing dua test coupon
M
– Semua harus lulus pemeriksaan dan pengujian
Electrode Clasification Groups
a
Group AWS Electrode Clasification
aj
dm
design
A
F4 EXX15, EXX16, EXX18, EXX48,
wi
EXX15-X, EXX16-X, EXX18-X
D
a
F3 EXX10, EXX11, EXX10-X, EXX11-X
tr
Pu
la
F2 EXX12, EXX13, EXX14, EXX13-X
da
an
F1 EXX20, EXX24, EXX27, EXX28,
M
EXX 20-X, EXX27-X
Position for test plate for groove
weld
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Position for test plate for fillet weld
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Position of test pipe
for groove weld 1G,
2G, 3G, 4G, 5G,
a
aj
6G, 6Gr
dm
A
wi
D
a
tr
Pu
la
da
an
M
Position of test pipe for fillet weld
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Test plate for WQT
Specimens for Procedure
Qualification
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen fractures
Position of fillet weld
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
AWS WPQ for Pipe and Square
Tubing
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Tabulation of positions of Fillet weld
Position Diagram Inclination Rotation of
a
aj
Reference of axis face
dm
Flat A 0 ° - 15 ° 150 °- 210 °
A
wi
Horizontal B 0 ° - 15 ° 125 °- 150 °
D
210 °- 235 °
a
tr
Overhead C 0 ° - 15 ° 0 ° - 125 °
Pu 235 ° - 360 °
la
Vertical D 0 ° - 15 ° 150 °- 235 °
da
an
E 0 ° - 15 ° 0 °- 360 °
M
Position of butt weld
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Tabulation of positions of Groove
welds
a
aj
Position Diagram Inclination Rotation of
dm
Reference of axis face
A
Flat A 0 ° - 15 ° 150 °- 210 °
wi
D
Horizontal B 0 ° - 15 ° 80 °- 150 °
a
tr
210 °- 280 °
Overhead Pu
C 0 ° - 80 ° 0 ° - 80 °
la
280 ° - 360 °
da
Vertical D 15 ° - 80 ° 80 °- 280 °
an
M
E 80 ° - 90 ° 0 °- 360 °
Position of welding
1G,2G, 3G, 4G, 5G,
a
6G, and 6 GR for
aj
pipe and tubular
dm
joint
A
wi
D
a
tr
Pu
la
da
an
M
Tension test
a
• Test on WQT, WPQ
aj
dm
• Weld Joint
A
– Germany, BKI standard test
wi
• Weld metal ( flush )
D
a
– American, Japanese standard test
tr
• Nick break test
– API 1104 standard
Pu
la
da
• Test Specimen
an
• Test coupon
M
• Tensile strength
Tension test specimen
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Test specimen of welding joint
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
Spesimen uji tarik
aj
a
Stress strain diagram
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Stress strain brittle material
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Mechanical properties
• σ, ultimate = P ultimate / Ao [ N/mm2 ]
a
aj
dm
• σ, Yield = P yield /Ao [ N/mm2 ]
A
wi
• ε, Elongation = ( Li – Lo ) / Lo [ % ]
D
a
tr
• Ra, Reduc.of Area = ( Ao – Ai ) /Ao [ % ]
Pu
σ / ε [ N/mm2]
la
• E,modulus Elasticity
da
an
• R, Resilience = ½ σ ε [ J/mm3 ]
M
Persyaratan Pemenuhan Standard
Uji Tarik
a
• ASME standard
aj
dm
– Kuat tarik hasil lasan tidak kurang dari
• Minimum tensile strength dari base metal
A
• Kuat tarik diambil yang terendah
wi
• Minimum tensile strength electrode yg dipakai
D
• Patah di daerah HAZ Tensile Strength boleh kurang 5% dari
a
kuat tarik BM
tr
• API 1104 standard
Pu
– Hasil Uji Tarik minimum sama dengan kuat tarik base
la
metal
da
• AWS D11 standard
an
M
– Kuat tarik hasil lasan tidak boleh lebih rendah dari
kuat tarik Base metal
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen Tension
Bending Test
a
• Face bend
aj
– Face part subjected to tension
dm
– 2 Specimens
A
– Thickness of the specimens up to 3/8 inch
wi
– Width of the specimens 1 ½ inch
D
• Root bend
a
– Root part subjected to tension
tr
– 2 Specimens
– Pu
Thickness of the specimens up to 3/8 inch
la
– Width of the specimen 1 ½ inch
da
• Side bend
an
– Side part subjected to tension
M
– 4 Specimens
– Thickness of the specimens more than 3/8 inch
– The width of the specimens 3/8 inch
FB,RB,SBend specimens
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
Specimen bending
a
Posisi mandrel pada uji bending
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Uji Bending pada mesin UTM
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Guided Bend Test Jig
Roller Guided Bend Jig
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Persyaratan Pemenuhan Standart
Uji Bending
a
• ASME Stndard
aj
dm
– Weld metal dan HAZ harus tertekuk
– Tidak boleh ada sobekan kearah mana saja lebih besar 1/8 inch
A
– Sobekan di pinggir boleh asal bukan karena cacat
wi
• API 1104 Standard
D
a
– Tidak boleh ada sobekan sebesar 1/8 inch atau 1/2 tebal pelat
tr
– Sobekan dipinggir boleh sampai 1/4 asal bukan dari cacat
• AWS D11 Standard Pu
la
– Max sobekan kesegala arah 1/8 inch
da
– Total sobekan sebesar 3/8 inch untuk sobekan antara 1/8 – 1/32
an
inch
M
– Sobekan pinggir boleh sampai 1/4 asal bukan karena cacat las
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen bending
Operation Loads of Structures
• Static Load
a
aj
– Tension σ, tensile
dm
– Bending σ, bending
A
– Shear G shear strength
wi
– Torsion
D
a
• Dynamic Load
tr
– Impact load Impact value
Pu
– Fatigue Load Fatigue strength
la
da
• Combine load
an
– Static load, tension and bending
M
– Dynamic load, fatigue in tension and bending
Impact value
a
• Dynamic test ( load )
aj
dm
• Impact value [ Joule ] ( 3 specimens )
A
wi
– Parameter for fatigue strength
D
– Parameter for ductile material
a
tr
• Transition temp ( 10 specimens )
la
Pu
– 50 % Brittle, 50 % Ductile
da
– Low temp to high temperature
an
M
– More higher transition temp more better
Standard Charpy Impact Specimen
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Placement of Charpy Impact
Specimen
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Impact testing machine
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Transition temperature
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
Ductile and brittle
aj
a
Detail permukaan patah
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Posisi pengambilan spesimen
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
Specimen Impact
a
Fracture test
a
• Fillet weld test
aj
dm
• WPQ two side weld
A
wi
• WQT one side weld stop and run in the
D
middle of the weld run
a
tr
Pu
• Length of specimen 6 inch or 4 inch
la
• Length of specimen 14 inch or 10 inch
da
an
• Fracture test is combine with macro etch
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen fractures
Acceptance criteria for fillet weld
break test 4.30.4.1
a
• To pass the visual examination prior to the break
aj
test, the weld shall present a reasonably uniform
dm
appearance shall be free of overlap, crack and
A
under cut in excess of requirement of 6.9 table
wi
6.1
D
• The broken specimen shall pass
a
tr
– The specimen bend flat upon it self.
Pu
– The fillet weld if fracture has a fracture surface
la
showing complete fusion to the root of the joint with no
da
inclusion or porosity larger than 3/32 inch in greatest
an
dimension.
M
– The sum of greatest dimension of all inclusion and
porosity shall not exceed 3/8 inch in the 6 inch long
specimen.
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen fracture
Macro etch preparation
a
• Macro etch specimen preparation
aj
dm
– Machining to make flat surface
– Wipe carefully with 120,240,320,400,500, 600, 800, 1000,
A
coarse abrasive paper
wi
– Wipe with aluminium hidrocide and wool to shining the surface
D
– Etch the surface with Alcohol plus Nitrid acid used ratio 95 to 5
a
tr
– Rinse using alcohol 95 % to protect corrosion
Pu
• Measure all the dimension of Base metal, HAZ, Weld
la
da
metal
an
– Measure all the parameters of the weld penetration, such as a
M
leg length, penetration etc
– Measure all of the defect if any
Macro etch test acceptance criteria 4.30.2.3
Welder and Welding Operator
• Fillet weld shall have fusion to the root to the joint but
a
aj
not necessary beyond.
dm
• Minimum leg size shall meet to the specify fillet weld
A
size.
wi
• Fillet weld and corner macro etch T,K,Y, connection on
D
box tubing shall have.
a
– No crack
tr
– Though fusion adjacent layer of weld metal and between weld
metal and base metalPu
la
– Weld profile conforming to intended detail on 5.24
da
– No under cut exceeding 1/32 inc ( 1 mm )
an
– For porosity 1/32 or larger accumulated porosity not exceeding
¼ inch ( 6 mm )
M
– No accumulated slag, the sum of the greatest dimension not
exceed ¼ inch
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Specimen macro etsa
Standard Welding Symbol
a
aj
dm
A
wi
D
Ir.Soeweify, M.Eng
a
tr
Head of Strength and Structure Groups
Pu
Department of Shipbuilding Engineering
la
Surabaya Institute of Technology
da
an
Welding Engineer 1980 Hiroshima University
M
Welding Inspector 1984 Hamburg University
Fracture Mechanic 1990 Bandung Institute of Technology
INTRODUCTION
One method for reducing the mass of information
contained in documents (especially drawings) is through
a
aj
the practice of using symbols. This practice replaces
symbols
dm
written words and detailed graphic illustrations with
A
specific symbols to convey the same information in an
wi
abbreviated manner.
D
a
Welding and nondestructive examination symbols are a
tr
"shorthand" method for conveying pertinent
Pu
information. This system provides a simple, yet
la
da
powerful method of describing detailed information. For
an
example, by using symbols the designer can easily
M
communicate a vast amount of information regarding
numerous aspects of the welding project to both
fabrication and inspection personnel.
Welding Symbols
a
Welding or examination symbols
aj
dm
can provide a great deal of information; however,
A
they must be used properly to be effective. If
wi
misapplied or misinterpreted, the symbols can
D
cause confusion, rather than aid in the
a
tr
understanding of some welding or testing detail.
Pu
For that reason, it is important to understand
la
da
how the welding and nondestructive examination
an
symbols are used.
M
Elements of the Welding Symbol
It is important to understand some of the
a
aj
terminology relating to symbols, before describing
dm
the various parts of a welding symbol. A basic
A
distinction is the difference between the terms
wi
weld symbol and welding symbol.
D
a
tr
The weld symbol indicates the type of weld, and when
Pu
used, is a part of the welding symbol.
la
da
The welding symbol is defined as "a graphical
an
representation of a weld." It is a method of representing
M
the weld symbol on drawings, and includes supplementary
information and consists of the eight elements.
Elements of the Welding Symbol
a
aj
(1) Reference line (shown horizontally)
dm
(2) Arrow
A
(3) Basic weld symbols
wi
(4) Dimensions and other data
D
a
(5) Supplementary symbols
tr
(6) Finish symbols Pu
la
(7) Tail
da
(8) Specification, process, or other reference
an
M
NOTE. It is not necessary to use all elements, unless
required for clarify
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
NONDESTRUCTIVE EXAMINATION SYMBOLS
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Location on Arrow Side
Examinations to be made on the arrow side of the part
shall be specified by placing the letter designation for
a
aj
the selected examination method below the reference
dm
line.
A
wi
D
a
tr
Pu
la
da
an
M
Location on the Other Side
Examinations to be made on the other side of the part
a
shall be specified by placing the letter designation for
aj
the selected examination method above the reference
dm
line.
A
wi
D
a
tr
Pu
la
da
an
M
Location on Both Sides
Examinations to be made on both sides of the part
shall be specified by placing the letter designation for
a
aj
the selected examination method on both sides of the
dm
reference line.
A
wi
D
a
tr
Pu
la
da
an
M
Location Centered on Reference Line
When the letter designation has no arrow- or other-
a
side significance, or there is no preference from
aj
which side the examination is to made, the letter
dm
designation shall be centered on the reference line.
A
wi
D
a
tr
Pu
la
da
an
M
Examination Combinations
More than one examination method may be specified
for the same part by placing the combined letter
a
designations of the selected examination methods in
aj
dm
the appropriate positions relative to the reference line.
Letter designations for two or more examination
A
methods, to be placed on the same side of the
wi
D
reference line or centered on the reference line, shall
a
be separated by a plus sign.
tr
Pu
la
da
an
M
Welding and NDE Symbols
Nondestructive examination symbols and welding
symbols may be combined.
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Examine-All-Around
Examinations required all around a weld, joint or part
a
shall be specified by placing the examine-all-around
aj
symbol at the junction of the arrow and reference
dm
lines.
A
wi
D
a
tr
Pu
la
da
an
M
Field Examinations
Examinations required to be conducted in the field
(not in a shop or at the place of initial construction)
a
aj
shall be specified by placing the field examination
dm
symbol at the junction of the arrow and reference
A
lines.
wi
D
a
tr
Pu
la
da
an
M
Radiation Direction
The direction of penetrating radiation may be specified
by use of the radiation direction symbol drawn at the
a
required angle on the drawing and the angle
aj
dm
indicated, in degrees, to ensure no misunderstanding.
A
wi
D
a
tr
Pu
la
da
an
M
Specifications, Codes, and References
Information, applicable to the examination specified
a
and which is not otherwise provided, may be placed in
aj
the tail of the nondestructive examination symbol.
dm
A
wi
D
a
tr
Pu
la
da
an
M
Length of Section to be Examined
To specify examination of welds or parts where only
the length of a section need be considered, the length
a
aj
dimension shall be placed to the right of the letter
dm
designation.
A
wi
D
a
tr
Pu
la
da
an
M
Location of Section to be Examined
To specify the exact location of a section to be
examined, as well as the length, dimension lines shall
a
aj
be used.
dm
A
wi
D
a
tr
Pu
la
da
an
When the full length of part is to be examined, no
M
length dimension need be included in the NDE symbol.
Partial Examination
When less than one hundred percent of the length of a
weld or part is to be examined, with locations to be
a
aj
determined by a specified procedure, the length to be
dm
examined is specified by placing the appropriate
A
percentage to the right of the letter designation. The
wi
selected procedure may be specified by reference in
D
the tail of the nondestructive examination symbol.
a
tr
Pu
la
da
an
M
Number of Examinations
To specify a number of examinations to be conducted
on a joint or part at random locations, the number of
a
aj
required examinations shall be placed in parentheses
dm
either above or below the letter designation away from
A
the reference line.
wi
D
a
tr
Pu
la
da
an
M
Areas of Revolution
For nondestructive examination of areas of revolution,
the area shall be specified by using the examine-all-
a
around symbol and appropriate dimensions.
aj
dm
A
The following illustration specifies:
wi
D
a
tr
(A) Magnetic particle examination
Pu
of the bore of the flange for a
distance of two inches from the
la
right hand face, all the way around
da
the circumference.
an
(B) Radiographic examination of an
M
area of revolution where
dimensions were not available on
the drawing.
Areas of Revolution
The symbol below specifies an area of revolution
subject to an internal proof examination and an
a
aj
external eddy current examination. Since no
dm
dimensions are given, the entire length is to be
A
examined.
wi
D
a
tr
Pu
la
da
an
M
Defect of Welding
a
aj
dm
A
wi
Ir.Soeweify, M.Eng
D
Head of Strength and Structure Groups
a
tr
Department of Shipbuilding Engineering
Pu
Surabaya Institute of Technology
la
da
Welding Engineer 1980 Hiroshima University
an
Welding Inspector 1984 Hamburg University
M
Fracture mechanic sertificate 1990 Bandung Institute of
Technology
Welding defect
a
• Metallurgical defect
aj
dm
– Melting process
A
• Incomplete fusion and incomplete penetration
wi
– Alloying process
D
• Slag inclusion and porousity
a
– Cristalization process
tr
Pu
• Cold crack and hot crack
• Dimensional defect
la
da
– Tranversal shrinkage
an
• Angular distortion
M
– Longitudinal shrinkage
• Longitudinal distortion
Weld defect
a
• Crack • Covexity
aj
dm
• Incomplete fusion • Weld reinforcement
A
• Incompl. penetration • Arc strike
wi
• Tungten Inclusion
D
• Slag inclusion
a
• Spatter
tr
• Porosity
• Under cut Pu • Delamination
la
• Lamelar tear
da
• Underfill
• Seams/lap
an
• Over lap
M
• Dimensional
Defect of Welding
a
• Metallurgical defect
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Crack of welding
a
• Hot crack, Cold crack
aj
dm
• Longitudinal crack,
A
Transversal crack
wi
D
• Base metal ,Weld
a
metal ,HAZ crack
tr
Pu
• Throat, root, toe,
la
under bead, crater
da
crack
an
M
• Lamelar tearing
Hot Crack
a
• Just start for cristalization
aj
dm
• Segregeration between cristal
A
wi
• Weld metal crack
D
• Crack of the first layer
a
tr
• Creater crack Pu
la
• Micro crack
da
an
• Transversal and logitudinal crack
M
The influence of hot cracking
Name of Form of crack Influence factor for cold
a
aj
crack cracking
dm
Wcond Chem Rs Bform
A
Crack on VVV VV VV VV
wi
D
the first
a
layer
tr
Dendrite
crack
Pu VVV VV VV VVV
la
da
an
M
Crater crack VVV VV V V
V
Hot Crack
a
• Welding condition
aj
dm
• Chemical
A
composition
wi
D
• Shrinking load of weld
a
point
tr
• Form of bead Pu
la
da
an
M
Crater crack
Crater crack is one of dangerous hot crack
a
aj
Crater crack occour in the
dm
end of weld couse of wrong
A
welding electrode
wi
manipulation, Filler metal
D
have flow characteristiecs
with produce concave profile
a
tr
when solidification
Pu
la
Hot crack start from crater
da
crack of fillet weld in pipe
an
welding, E 308 -16, E 309-
M
16, E 316 -16, The welder
must take care the end of
welding to full fill the crater
Preventive Methode of the Hot cracking for each material
Sensitivity Preventive Methods
For For For
Kind of Crack of Weld Metal Crack Material Prose De
Material In dur sign
a
First Layer Dendrit Micro Other the
aj
Crack Crack Crack Crack HAZ
HAZ
dm
40 Midle Midle Low Midle Low
Kg/mm2 sensitive sensitive sensitive sensitive sensitive
A
Reduce of Examine Low
C necc to care necc to No necc to No
P.S weld Shrink
care Problem care Problem
wi
A Increase conditio age
R 50 of Mn n Pre
D
Midle Midle Low Midle Low
B Kg/mm2 examine examine vent
sensitive sensitive sensitive sensitive sensitive
of the format Stress
a
O necc necc No necc No
elememt weld
tr
N care Care Problem care Problem
bead.
60
S Kg/mm2
Midle
sensitive
Midle
sensitive Pu
Low
sensitive
Midle
sensitive
Low
sensitive
la
necc necc No necc No
T care Care Problem care Problem
da
E
E 70 Midle Midle Low Midle Midle
an
L Kg/mm2 sensitive sensitive sensitive sensitive sensitive
M
necc to care necc to No necc to necc to
care Problem care care
80 Midle Midle Low Midle Midle
Kg/mm2 sensitive sensitive sensitive sensitive sensitive
necc necc No necc necc to
care care Problem care care
Preventive Methode of the Hot cracking for each material
Cr- Midle Midle Low Midle Low
½ Mo sensitive sensitive sensitive sensitive sensitive
necc necc to No necc to No
care care Problem care Problem
a
1Cr – Midle Midle Low Midle Low
aj
½ Mo sensitive sensitive sensitive sensitive sensitive
necc to care necc No necc No
dm
Care Problem care Problem
L Reduc of Examine
O 1 ¼ Cr –
A
Midle Midle Low Midle Low P.S weld
W ½ Mo sensitive sensitive sensitive sensitive sensitive Increase codition
wi
necc necc No necc No of Examine Low
A care Care Problem care Problem Mn format Shrink
D
L Examined weld age
of the bead. Pre
L 2 ¼ Cr – Midle Midle Low Midle Low
a
elememt Clean vent
tr
sensitive sensitive sensitive sensitive sensitive
O ½ Mo necc necc to No necc to No Keep SC
Y
Pu
care care Problem care Problem enough
Slag
S 3 Cr – Midle Midle Low Midle Low
la
T ½ Mo sensitive sensitive sensitive sensitive sensitive
da
E necc to care necc No necc No
E Care Problem care Problem
an
L
5 – 9 Cr Midle Midle Low Midle Low
M
– ½ Mo sensitive sensitive sensitive sensitive sensitive
necc necc to No necc to No
care care Problem care Problem
Mn - Mo Midle Midle Low Midle Low
sensitive sensitive sensitive sensitive sensitive
necc necc No necc No
care care Problem care Problem
Preventive Methode of the Hot cracking for each material
Austenit Midle sensitive Midle High Midle Midle Reduc of Examine
necc to care sensitive sensitive sensitive sensitive P.S weld
S necc Must care necc necc to Increase codition Low
a
T care care care of Mn Take of Shrink
aj
A Martensit Midle sensitive Midle Midle Midle Midle Examin of crater age
necc sensitive sensitive sensitive sensitive the Examine Prevent
I
dm
care necc to necc to necc to necc to element format Stress
N care care care care Reduced weld Concent
L Ferrit Midle sensitive Midle Midle High Midle Harmful bead.
A
E necc sensitive sensitive Sensitive sensitive element Clean
E
wi
care necc not care Must care necc to Pb,B,O Keep
S care care Keep delts enough
D
ferrite Slag
Pure High sensitive Midle High High Midle
a
Nikkel Must care sensitive sensitive sensitive sensitive Reduce Examine
tr
necc Must care Must care necc to PS weld
care care Increase codition
N
Inconnel High sensitive
Must care
High
sensitivePu High
sensitive
High
sensitive
High
sensitive
Mn
Reduce
Examine
format
Low
Shrink
la
Must care Must care Must care Must care Harmful weld age
I Hactelloy High sensitive Midle Midle High Midle elemen, bead. Prevent
da
Must care sensitive sensitive sensitive sensitive Pb,B,O Clean Stress
B necc necc Must care necc to Add little Keep
an
A care care care element enough
Ti,Nb.Al,Ni Slag
S Monel High sensitive High High High Midle
M
Must care sensitive sensitive sensitive sensitive Examine Apply
E Must care Must care Must care necc to element peening
care comp
Cold crack
a
• Process of crack • Caused of crack
aj
dm
– Finish cristalization – Chemical composition
A
– Hydrogen diffusible – Welding heat input
wi
– Stress at the weld – Hydrogen diffusible
D
metal
a
– Restraint of joint
tr
– HAZ and base metal
crack Pu – Residual stress
la
– Diforation anggle
da
– Root crack
an
– Toe crack
M
– Under bead crack
The influence of cold cracking
a
Name Form of crack Influence factor for cold
aj
dm
of cracking
crack
A
Wh Hdiff Pcm R A Rs
wi
D
VV VV VV VV VV
a
V V V V
tr
Pu
la
Root
da
crack VV VV VV V VV
an
V V
M
The influence of cold cracking
a
Name Influence factor for cold
aj
dm
of Form of crack cracking
crack
A
Wh Hd Pcm R A Rs
wi
D
VV VV VV V VV
a
V V V
tr
Pu
la
Toe
da
crack VV VV V V V
an
V
M
The influence of cold cracking
a
Name Influence factor for cold
aj
dm
of Form of crack cracking
crack
A
Wh Hd Pcm R A Rs
wi
D
Under VV VV VV VV VV
a
bead V V
tr
crack
Pu
la
da
Lame V VV V VV VV
an
lar V V
M
tear
ing
Longitudinal and transversal crack
a
aj
dm
Longitudinal
crack start from
A
the weld toe in
wi
D
the HAZ
a
tr
Transvers crack Pu
la
da
start from the
an
stop and run of
M
weld
Longitudinal and transversal crack
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Under bead crack
a
Under bead crack
aj
dm
Some kind of cold
A
crack
wi
Start from the toe of
D
a
weld in HAZ
tr
Pu
Mainly caused by la
Hydrogen diffusible
da
an
M
Effect of pre heating on root
craking
a
• Experimental results
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Couse and Prevention Cracks on
the HAZ
a
• Couse • Preventive
aj
dm
– Base metal have high – Chose the lower Cek
A
hardenability and Pcm
wi
– High C ek and P cm – Elec. Low hydrogen
D
– C, Mn,Cr conten to – Dry Filler metal
a
tr
high – Clean edge
Pu
– Hidrogen diffusible preparation
la
da
– Hidrogen – Moderate high restrain
an
Embrittlemen – Good weather
M
– High restrain joint – Pre heating and post
heating
Lamelar tearing
Thick material only
a
aj
dm
Delamination first
A
High Stress through the
wi
thickness
D
a
Fillet weld only
tr
Degree of constraint Pu
la
da
High inclusion of base
an
metal
M
Low transverse ductility
High residual stress
M
an
da
la
Lamellar tearing
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Lamellar tearing
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
Lamellar tearing
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
Lamelar tearing
aj
a
Lamelar tearing
• Lamelar tearing • Lamellar tearing
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Incomplete fusion
a
• Low heat input
aj
dm
• Travel speed to high
A
• Amperage to low
wi
D
• Wrong electrode
a
tr
position
Pu
• Weld metal to weld
la
metal
da
an
• Weld metal to base
M
metal
Incomplete fusion
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Typical side wall incomplete
fusion
Incomplete penetration
a
aj
dm
A
wi
D
a
tr
Pu
la
Couse of Incomlete penetration
da
Diameter electrode to big
Groove angle to small
an
Amperage to low
M
Wrong electrode not deep penetration
Weld metal does not extend entirely
Incomplete penetration
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
M
Incomplete penetration Incomplete penetration
on radiography in root of weld
Slag inclusion
a
• Incorrect welding
aj
dm
parameter
A
• Difficult to clean slack
wi
• Molten slack to thick
D
• Oxidation and
a
tr
deoxidation process
• Unadequate weld Pu
la
preparation
da
• Iregular visual in X Ray
an
M
• Black vision on DT
Porosity
a
• Gas entrapment
aj
dm
during solidification
A
• The least dangerous
wi
• H2S, CO, NO2
D
• Uniformly scattered
a
tr
• Clustered porosity
Pu
la
• Piping porosity
da
• Linear porosit
an
M
• Dirty base metal
Under cut
• Under Cut
a
– Amperage to high
aj
dm
– The wrong welding
technique
A
wi
– Angle of electrode
D
during welding
a
tr
– Initial crack start from
this defect Pu
la
– Maximum 0.5 mm
da
an
M
M
an
da
la
Pu
tr
a
D
wi
Under fill
A
dm
aj
a
Over lap
a
• Over lap
aj
dm
– Protrusion of weld
A
metal beyond the
wi
weld toe
D
– Wrong electrode
a
tr
position
– Burn torch Pu
la
da
an
M
a
aj
dm
A
wi
D
a
tr
Pu
la
da
an
WELD GEOMETRY &
M
WELDING TERMINOLOGY
PURPOSES
a
• Student should understand joint
aj
dm
configurations and their parts.
A
wi
• Student should be able to recognize any
D
welding positions and problems that may
a
tr
arise. la
Pu
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Design consideration for choosing
edge preparation
a
aj
• WELDING PROCESS
dm
• MATERIAL THICKNESS
A
• ACCESSIBILITY
wi
D
• FABRICABILITY
a
tr
• STRENGTH
• ECONOMICS Pu
la
da
an
M
Fabrication Process
a
aj
• SHEARING shearing machine
dm
• MACHINING lathe, grind
A
• THERMAL gouge, flame
wi
D
a
tr
Pu
la
da
an
M
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
Positions of Welds
Welding can be done in any positions depending upon
a
conditions and locations of construction to be joined. Both
aj
dm
fillet and butt joints for pipes and plates have classification of
weld positions, ranging from low to high difficulty level.
A
wi
American Welding Society has classified welding positions into
D
four main possitions based on its difficulty level:
a
tr
• FLAT (F) Pu
la
• HORIZONTAL (H)
da
an
• VERTICAL (V)
M
• OVERHEAD (OH)
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
M
an
da
la
Pu
tr
a
D
wi
A
dm
aj
a
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