Welding_ Cutting and Brazing

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					Welding, Cutting and Brazing

  29 CFR 1910.251 & 1926.350
        Subpart Q & J



       By: Chou Lor, Safety Coordinator

                   UW-Eau Claire
        Facilities Planning & Management
   Welding, Cutting and Brazing
• Training Objectives
  –   Three Specific Types of Welding Modules
  –   Methods of Arc Welding
  –   Welding Hazards
  –   Safe Work Practices
  –   Fire Protection & Prevention
  –   Proper Ventilation for Welding
  –   Welding Operators Protection


                            UW-Eau Claire
                 Facilities Planning & Management
 Three Specific Types of Welding
            Modules
• In this Welding, Cutting, and Brazing
  module, three specific types of welding are
  covered. These are listed below:
  – Oxygen-fuel gas welding and cutting
  – Arc welding and cutting
  – Resistance welding




                         UW-Eau Claire
              Facilities Planning & Management
Oxygen-fuel gas welding & Cutting

• The elements of Oxygen-fuel gas welding
  and cutting:
  –   General Requirements
  –   Cylinders
  –   Service Pipe Systems
  –   Pipe System Protection




                          UW-Eau Claire
               Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• General Requirements
  – Focuses on using Acetylene Safely
    • Flammable
    • Unstable
    • Cannot be adjusted above 15 psi
  – Safe Work Practices                            •   The pressure adjusting screw:
                                                        –   Turning clockwise allows the gas
    • Blow out cylinder valve                               allows to flow.
                                         –                  Turning counterclockwise
    • Turn on cylinder valve first and                      reduces or stop the gas flow.

      then adjust the regulator pressure screw.
    • Never stand in front or behind
      a regulator when opening the cylinder valve
    • Open cylinder valve slowly
                           UW-Eau Claire
                Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• General Requirements Cont.:
  – Safe Work Practices
    •   Purge oxygen and acetylene passages
    •   Light the acetylene
    •   Never use oil or grease
    •   Do not use oxygen as a substitute for air
    •   Keep your work area clean




                            UW-Eau Claire
                 Facilities Planning & Management
 Oxygen-fuel gas welding and cutting
• Cylinders
  – Cylinder approval and marking
    • marked for the purpose of identifying the gas content,
      with either the chemical or trade name of the gas

  – Storage of cylinders
    • Storage area must be well ventilated
    • Cylinders must be at least 20 feet from combustibles
    • Valves must be closed
    • Valve protection must be in place
    • Inside storage must be limited to 2,000 cubic feet.
    • Cylinders must be stored in upright position
    • Oxygen must be at least 20 feet from fuel gas
      or 5 feet with a 1/2 hour fire barrier
    • Separate oxygen from fuel gas


                               UW-Eau Claire
                    Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• Cylinders Cont.:
  – Operating Procedures
    • Operation must emphasize the absence
      of oily or greasy substances. Follow these
      rules of operation:
       – Cylinders, cylinder valves, couplings,
         regulators, hose, and apparatus shall be kept
         free from oily or greasy substances.
       – Oxygen cylinders or apparatus shall not be
         handled with oily hands or gloves.
       – A jet of oxygen must never be permitted to
         strike an oily surface, greasy clothes, or enter
         a fuel oil or other storage tank.

                           UW-Eau Claire
                Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• Service Pipe Systems
  – There are special requirements for service
    pipe systems when using oxygen or
    acetylene.
    • Oxygen
    • Acetylene or Acetylene Compounds




                         UW-Eau Claire
              Facilities Planning & Management
Oxygen-fuel gas welding and cutting

• Pipe System Protection
  – The entire service pipe system must be
    protected against build-up of excessive
    pressure and leaks. This protection is
    accomplished with:
    • Protective equipment
    • Regulators
    • Proper hose and hose connections.



                         UW-Eau Claire
              Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• Pipe System Protection Cont.:
  – Protective equipment is divided into the two
    categories listed here:
    • Pressure Relief Devices
       – The pressure relief device should discharge upwards to
         a safe location.
       – Pressure relief valves are required in fuel-gas piping
         systems to prevent excessive pressure build up within
         the system.




                           UW-Eau Claire
                Facilities Planning & Management
Oxygen-fuel gas welding and cutting
• Pipe System Protection Cont.:
  – Approved protective equipment shall be
    installed in fuel-gas piping to prevent:
     • Backflow of oxygen into the fuel-gas supply
       system
     • Passage of a flash back into the fuel-gas
       supply system
     • Excessive back pressure of oxygen in the
       fuel-gas supply system.
                         UW-Eau Claire
              Facilities Planning & Management
     Arc Welding and Cutting
• Definition:
  – A fusion process wherein the coalescence of
    the metals is achieved from the heat of an
    electric arc formed between an electrode and
    the work.
     • Application
     • Installation
     • Operation & Maintenance




                           UW-Eau Claire
                Facilities Planning & Management
       Arc Welding & Cutting
• Application
  – Applies to a large and varied group of
    processes that use an electric arc as the
    source of heat to melt and join metals.
• Installation
  – Arc welding requires proper installation of
    equipment.
  – A critical part of installation is ensuring that
    proper grounding is completed.

                          UW-Eau Claire
               Facilities Planning & Management
          Arc Welding & Cutting
• Operation & Maintenance
  – All connections to the machine shall be checked
    to make certain that they are properly made.
  – The work lead shall be firmly attached to the
    work.
  – Magnetic work clamps shall be free from
    adherent metal particles of spatter on contact
    surfaces.
  – Coiled welding cable shall be
    spread out before use to avoid
    serious overheating and
    damage to insulation.Claire
                     UW-Eau
               Facilities Planning & Management
        Arc Welding & Cutting
• Operation and Maintenance Cont.:
  – During welding operations, cables with splices
    within 10 feet (3m) of the holder shall not be
    used.
  – Welders should not coil or loop welding
    electrode cable around parts of their body.
  – Cables with damaged insulation or exposed
    bare conductors shall be replaced.
  – Joining lengths of work and electrode cables
    shall be done by the use of connecting means
    specifically intended for that purpose.
  – The connecting means shall have insulation
    adequate for the service conditions.
                         UW-Eau Claire
              Facilities Planning & Management
          Resistance Welding
• Definition:
  – This is a group of fusion welding processes
    that use heat and pressure to make the
    coalescence.
     • The heat comes from electrical resistance to
       current flow at the site of the weld.
  – The processes include:
     • Spot Welding
     • Projection Welding
     • Seam Welding
    Note: FP&M only does spot welding.
                             UW-Eau Claire
                  Facilities Planning & Management
          Resistance Welding
• Spot Welding
  – A process typically used in high-volume, rapid
    welding applications.
     • The pieces to be joined are clamped between two electrodes
       under force, and an electrical current is sent through them.
  – The advantages of spot welding are many and
    include the fact that it is:
     • An economical process
     • Adaptable to a wide variety of materials including low carbon
       steel, coated steels, stainless steel, aluminum, nickel,
       titanium, and copper alloys
     • Applicable to a variety of thicknesses
     • A process with short cycle times
     • A robust process
     • Tolerant to fit-up variations

                             UW-Eau Claire
                  Facilities Planning & Management
     Welding/Cutting Hazards
• Potential Hazards
  – Fires may start by hot materials igniting
    nearby combustibles.
  – Burns to the operator may occur if unprotected
    skin comes into contact with the extremely hot
    work.
  – Magnetic fields could easily
    destroy/disrupt electronic
    components, stored data if
    not careful.

                         UW-Eau Claire
              Facilities Planning & Management
       Welding/Cutting Hazards
• Potential Hazards Cont.:
  – Metal fumes from vaporizing of the work with the
    extremely hot arcs may be inhaled into the worker’s
    lungs.
  – Certain metals and metal oxide fumes, including zinc,
    cadmium and beryllium, produce serious illnesses
    when inhaled.
  – Fluxes used with welding to create inert atmospheres
    at the point of the weld also present inhalation
    hazards.
  – All welding and cutting must have adequate
    ventilation to protect the person doing the welding
    and those working around the welding area.
                           UW-Eau Claire
                Facilities Planning & Management
     Methods of Arc Welding
• Three Types of Welding Methods:
  – Tungsten Inert Gas Welding (TIG)
  – Gas Metal Arc Welding (MIG)
  – Shielded Metal Arc Welding (SMAW)/ Stick
    Welding




                        UW-Eau Claire
             Facilities Planning & Management
  Tungsten Inert Gas Welding (TIG)
• Definition:
   – TIG welding is an arc that is formed
     between a non-consumable tungsten
     electrode and the metal being welded.
   – Gas is fed through the torch to shield the
     electrode and molten weld pool.
• Benefits:
   – Welds with or without filler metal
   – Precise control of welding
     variables (heat)
   – Low distortion
• Shielding Gases:
   – Argon
   – 2 to 5% Hydrogen
   – w/Helium
                              UW-Eau Claire
                   Facilities Planning & Management
Tungsten Inert Gas Welding (TIG)
• Applications
    • Most commonly used for aluminum and
      stainless steel
    • For steel
      – Slower and more costly than consumable
        welding
      – Except for thin sections or where very high
        quality is needed




                        UW-Eau Claire
             Facilities Planning & Management
     Gas Metal Arc Welding (MIG)
• Definition:
  – The heat source is formed by creating an
    electric arc between the work piece and a wire,
    which is fed continuously into the weld pool.
• Benefits:
  – Long welds can be made
    without starts and stops
  – Minimal skill required
  – Minimal cleaning of
    surface before weld
  – Allows welding in all
    positions         UW-Eau Claire
                  Facilities Planning & Management
Gas Metal Arc Welding (MIG) Cont.
• Shielding Gases:
     • Inert
         – Argon, Helium
           » Used for aluminum alloys and stainless steels.
     • Active
        – 1 to 5% Oxygen, 3 to 25% CO2
           » Used for low and medium carbon steels

• Applications
     • Gas Metal Arc Welding (MIG) is used to weld all
       commercially important metals, including steel,
       aluminum, copper, and stainless steel.
                            UW-Eau Claire
                 Facilities Planning & Management
       Shielded Metal Arc Welding
         (SMAW)/Stick Welding
• Definition:
  – Consumable electrode coated with
    chemicals that provide flux and shielding
  – The filler metal (here the consumable
    electrode) is usually very
    close in composition to
    the metal being welded.




                           UW-Eau Claire
                Facilities Planning & Management
       Shielded Metal Arc Welding
         (SMAW)/Stick Welding
• Benefits
     • Simple, portable,& inexpensive
     • Self flux provided by electrode
     • Provides all position flexibility
• Shielding Gases
     • No shield gases added
     • Lower sensitivity to Wind


                          UW-Eau Claire
               Facilities Planning & Management
    Shielded Metal Arc Welding
   (SMAW)/Stick Welding Cont.:
• Applications
     • Construction, pipelines, shipbuilding,
       fabrication job shops.
     • Used for: Steels, stainless steels, cast irons.
     • Not used for aluminum and its alloys, or
       copper and its alloys (energy density is too
       high).



                          UW-Eau Claire
               Facilities Planning & Management
                        Cutting
• Definition:
  – A stream of oxygen is directed against a piece of
    heated metal, causing the metal to oxidize or burn
    away.
• Making a Cut
  – Mark a line as a guide.
  – Turn on acetylene as for welding and light.
  – Turn on oxygen adjusting flame to neutral.
  – Make sure the oxygen lever flame remains neutral.
  – Place metal on the cutting table so metal will fall
    clear.
  – Flame Types:

                           UW-Eau Claire
                Facilities Planning & Management
                         Brazing
• Definition:
  – A process which a filler metal is placed at or between
    the faying surfaces, the temperature is raised high
    enough to melt the filler metal but not the base metal.
     • The molten metal fills the spaces by capillary attraction.
• Torch Brazing
  – Oxy-fuel torch with a carburizing flame
  – First heat the joint then add the filler metal



                             UW-Eau Claire
                  Facilities Planning & Management
       Safe Work Practices
• Electric & Gas Welding
  – Safety Check:
    • Ensure electrical cord, electrode holder
      and cables are free from defects
       – No cable splices within 10 feet of electrode holder.
    • Ensure welding unit is properly grounded.
     This helps to avoid over heating.
    • All defective equipment shall be repaired
      or replaced before using.

                          UW-Eau Claire
               Facilities Planning & Management
           Safe Work Practices
• Electric & Gas Welding Cont.:
  – Safety Check:
    • Remove all jewelry – rings, watches, bracelets,
      etc…
    • Ensure PPE e.g.. welding hood, gloves, rubber
      boots or safety shoes, apron are available and in
      good condition.
    • Ensure fire extinguisher is charged and available.
    • Ensure adequate ventilation and lighting is in place.
    • Set Voltage Regulator to Manufacture’s
      specifications.
    • Avoid electrical shock DON’T wrap cables around
      any body part.
    • Ensure fittings are tight.

                           UW-Eau Claire
                Facilities Planning & Management
      Safe Work Practices
• Electric & Gas Welding Cont.:
  – Safety Check:
    • Inspect hoses for cuts and frayed areas.
    • Set gauges to desired PSI.
    • Ensure that sufficient PPE is made
      available.
    • Locate welding screens to protect
      employee’s – DON’T block your exit.
    • Ensure that adequate ventilation and
      lighting are in place.
                      UW-Eau Claire
           Facilities Planning & Management
   Fire Protection & Prevention
• Fire hazards must be removed, or
  – Guards installed, or
  – Welding/cutting must NOT take place
• Hot work permit should be used
  outside designated areas to ensure
  that all fire hazards are controlled
• Use of fire watch
  – 1/2 hour after operation ceases




                           UW-Eau Claire
                Facilities Planning & Management
Fire Protection & Prevention Cont.:
• Welding areas should meet the following
  requirements:
  – Floors swept & cleared of combustibles 35 ft.
    radius of work area.
  – Flammable and combustible liquids kept 35 ft.
    radius of work area.
  – At least one fire extinguisher – on site
  – Protective dividers to contain sparks    and
    slag
     • Welding curtains
     • Non-combustible walls
     • Fire resistant tarps & blankets

                              UW-Eau Claire
                   Facilities Planning & Management
    Proper Ventilation for Welding
• Ventilation
  – Proper ventilation can be obtained either naturally or
    mechanically.
     • Natural Ventilation is considered sufficient for welding and
       brazing operations if the present work area meets these
       requirements:
         – Space of more than 10,000 square feet is provided per welder
         – A ceiling height of more than 16 feet.
     • Mechanical ventilation options generally fall into two basic
       categories.
         – Low vacuum system which takes large volumes of air at low
           velocities.
         – High vacuum system that are captured and extracted fumes as
           near to the work as possible.

                             UW-Eau Claire
                  Facilities Planning & Management
  Proper Ventilation for Welding
• Ensure protection from fumes
  and gases by one or a
  combination of the following:
  – Good general ventilation.
  – Use of a booth.
  – Local exhaust ventilation
    on the hand piece.
  – Air supply to the helmet.


                        UW-Eau Claire
             Facilities Planning & Management
      Welding Operators Protection
• Welding involves specialized personal
  protection that must be worn every time
  you perform welding operations. The
  following is a list of basic PPE:
  –   Fire-resistant gloves
  –   Aprons
  –   Safety shoes
  –   Helmet
  –   Ultraviolet radiation filter plate (arc welding)
  –   Goggles with filter lenses

                              UW-Eau Claire
                   Facilities Planning & Management
 Welding, Cutting and Brazing
• Summary
 – Major hazards include:
   •   Fire
   •   Burns
   •   Shock
   •   Toxic Exposure
 – Follow proper procedures to prevent fires
 – Use appropriate engineering controls
 – Wear appropriate PPE

                          UW-Eau Claire
               Facilities Planning & Management
Any Questions


    ??
            UW-Eau Claire
 Facilities Planning & Management

				
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