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					WELDER‘S

HANDBOOK




       WELDER’S HANDBOOK
                Page 1 of 26
Welder’s Handbook


                  TABLE OF CONTENTS
1.   Weld Defects, Causes and Cure

2.   Acceptable and Unacceptable Weld Profiles

3.   Welding Positions




        WELD DEFECTS, CAUSES AND CURE
                                            WELDER’S HANDBOOK
                                                     Page 2 of 26
A.   Weld Spatter

       Sketch:
                    SPATTERS




       Causes:
       1.   Current too high.
       2.   Wrong Polarity.
       3.   Arc length too long.
       4.   Presence of arc blow.
       5.   Wet electrodes

       Cure:
       1.    Try lowering the current. Be sure the current is within
             the range for the type and diameter of the electrode.
       2.    Be sure the polarity is correct for the electrode type.
       3.    Try a shorter arc length.
       4.    If the molten metal is running in front of the arc, change
             the electrode angle.
       5.    Look for arc blow conditions, and control it as follows;
             5.1 Change to AC welding.
             5.2 Use lower current and smaller electrodes.
             5.3 Try reducing the arc length.
             5.4 Weld in the direction of the blow.
             5.5 Change the electrical path to work by:
                    5.5.1 Shifting the work connection to the other
                          end of the work or making connections in
                          several locations.
                    5.5.2 Welding toward heavy tacks, finished
                          welds, or back-stepping on long welds.


                                               WELDER’S HANDBOOK
                                                        Page 3 of 26
                   5.5.3 Using run-out tabs, adding steel blocks to
                         change work current path, or tacking small
                         plates across the seam at weld ends.
        6.    Observe the proper handling of welding electrode.

B. Overlap
        Sketch:
                                               Overlap




        Causes:
        1.   Welding current too low and travel speed too slow.
        2.   Contaminated base metal.

        Cure:
        1.    Increase the welding current and the travel speed.
        2.    Clean the joint properly.

C. Underfill
        Sketch:
                                           Underfill




        Causes:
        1.   Failure to fill the joint completely prior to the deposition
             of the cap pass.

        Cure:
        1.    Fill the joint up to the base metal thickness or at least
              1mm below prior to the deposition of cap pass.
                                                   WELDER’S HANDBOOK
                                                            Page 4 of 26
C. Arc Strikes
        Sketch:




        Cause:
        1.    Carelessness of the welder.
        Cure:
        1.    Properly secure all ground connections, welding cables
              and electrode handle/gun.

D. Undercut
       Sketch:




        Causes:
        1.    Current too high.
        2.    Wrong electrode angle.
        Cure:
        1.    Decrease the current and the travel speed.
        2.    Change electrode angle so the arc force holds the
              metal in the corners. Use a uniform travel speed, and
              avoid excessive weaving.
                                              WELDER’S HANDBOOK
                                                       Page 5 of 26
E. Porosity
        Sketch:




        (a)   Cluster Porosity
              Causes:
              1.   Unstable or poor shielding.
              2.   Improper initiation or termination of weld.

              Cure:
              1.    Keep the arc length as close as possible.
              2.    For the initiation of the arc, use the back-stepping
                    method to re-melt the cold start area and float the
                    gas out of the bead. Whenever possible, use tab
                    plates on each end of the joint.

        (b)   Piping/Wormhole Porosity
              Causes:
              1.   Contaminated base metal.
              2.   Poor or unstable shielding i.e. poor moisture and
                   wind protection, too long arc length, unstable
                   electrode manipulation.
              3.   The electrodes absorbed moisture.

              Cure:
              1.    Observe proper cleaning of the joint for welding.
              2.    Keep the arc length as close as possible.
              3.    Avoid too wide weaving.
              4.    Install proper wind protection on the work area.

                                                WELDER’S HANDBOOK
                                                         Page 6 of 26
              5.    Observe the proper handling of welding
                    electrode.
              6.    For GTAW process, increase the shielding gas
                    flow rate as required. Also, check the gas hose
                    and connections for possible leakage.

F. Slag Inclusion
         Sketch:




                                             WELDER’S HANDBOOK
                                                      Page 7 of 26
       Causes:
       1.   Poor inter-pass cleaning.
       2.   Current too low.
       3.   Unstable electrode manipulation
       4.   Groove angle too narrow.
       5.   Weld beads too convex.

       Cure:
       1.    Observe proper inter-pass cleaning.
       2.    Increase the current.
       3.    Correct the too convex bead by grinding.

G. Burn-Through
        Sketch:




       Causes:
       1.   Too wide root gap, and too short root face.

       Cure:
       1.    Correct the joint preparation.
       2.    Decrease the current, and increase the welding speed.




                                              WELDER’S HANDBOOK
                                                       Page 8 of 26
H. Internal Concavity
         Sketch:




        Causes:
        1.    Higher current.
        2.    Arc length too long.
        3.    Root gap too wide, and groove angle too narrow.
        Cure:
        1.    Decrease the current, increase the welding speed.
        2.    Make arc length as close as possible.
        3.    Correct the joint preparation.

I. Incomplete Fusion

        Causes:
        1.   Groove angle too narrow.
        2.   Welding speed too high.
        3.   Weld beads too irregular.

        Cure:
        1.    Increase the current and decrease the welding speed.
        2.    Correct the joint preparation.
        3.    Correct the irregular bead by grinding.




                                              WELDER’S HANDBOOK
                                                       Page 9 of 26
Sketch:




          INCOMPLETE FUSION




                  WELDER’S HANDBOOK
                           Page 10 of 26
J. Incomplete Root Penetration
        Sketch:




        Causes:
        1.   Current too low.
        2.   Arc length too long.
        3.   Improper joint preparation i.e. root face too long, root
             gap too narrow, groove angle too narrow.

        Cure:
        1.    Increase the current.
        2.    Make arc length as short as possible.
        3.    Correct the joint preparation.

K. Excessive Reinforcement

        Causes:
        1.    Welding speed too slow.
        2.    Improper welding technique.
        Cure:
        1.    Increase the welding speed.
        2.    Grind the excess thickness of the last layer to base
              metal prior to deposition of cap pass.
        3.    Use the proper size of welding electrode.
                                              WELDER’S HANDBOOK
                                                       Page 11 of 26
        Sketch:




L. Excessive Penetration

        Sketch:




                                         Excess Penetration



        Causes:
        1.   Root gap too wide, and root face too short.
        2.   Current too high.

        Cure:
        1.    Correct the joint preparation.
        2.    Decrease the current, and increase the travel speed.




                                               WELDER’S HANDBOOK
                                                        Page 12 of 26
M. Cracking
        Sketch:




                  WELDER’S HANDBOOK
                           Page 13 of 26
(a)   Cold Cracks (Toe/Underbead Cracks)
      Causes:
      1.    Rapid cooling from the welding temperature of a
            relatively high carbon or alloy content steel.
      2.    Hydrogen pick-up during welding.
      3.    The joint is so restrained.

      Cure:
      1.    Use low hydrogen welding electrodes.
      2.    Observe proper handling of electrodes, and
            cleanliness of the joint for welding.
      3.    Preheat the joint to reduce the cooling rate, and
            maintain the inter-pass temperature.
      4.    Reduce penetration by using low currents, small
            electrodes. This reduces the amount of alloy
            added to the weld from melted base metal.
      5.    For GTAW process, check the gas hose and
            connections for possible leaks. Verify also the
            purity of shielding gas and change with a higher
            grade if found necessary.

(b)   Hot Cracks (Crater/Throat/Root Cracks)
      Causes:
      1.    Wrong welding technique.

      Cure:
      1.    To control crater cracking, fill each crater before
            breaking the arc.
      2.    On multiple pass or fillet welds, be sure the first
            bead is of sufficient size and of flat or convex
            shape to resist cracking until the later beads can
            be added for support. To increase bead size, use
            slower travel speed, a short arc, or weld 5O uphill.
            Always continue welding while the plate is hot.
      3.    For rigid joints, whenever possible, weld towards
            the unrestrained end. Leave at least 1/32” gap
            between plates for free shrinkage as the weld
            cools.
                                        WELDER’S HANDBOOK
                                                 Page 14 of 26
N. Tungsten Inclusion (GTAW Process)
       Sketch:




        Cause:
        1.   Accidental touching of the tungsten electrode to the
             weld puddle.

        Cure:
        1.    Avoid contact of the tungsten electrode with the molten
              weld puddle.

O. Insufficient Leg Size (Fillet Welds)
         Sketch:


                                                 S2



                       S1




        Cause:
        1.    Incorrect electrode angle.
        2.    Improper welding technique.
        Cure:
        1.    Use the correct electrode angle.
        2.    For multi-pass fillet welds, follow the proper weld pass
              sequence to attain the required leg size.
        3.    Use the correct diameter of the electrode for each pass.
                                               WELDER’S HANDBOOK
                                                        Page 15 of 26
      ACCEPTABLE AND UNACCEPTABLE WELD
                  PROFILES
A.    DESIRABLE FILLET WELD PROFILES




B.    ACCEPTABLE FILLET WELD PROFILES




Note: Convexity “C” of a weld or individual surface bead with dimension
“W” shall not exceed the following value;


        Width of Weld Face or
     Individual Surface Bead, W             Maximum Convexity, C
W < 5/16” (8mm)                          1/16” (2mm)
W > 5/16” (8mm) to W < 1 IN. (25mm)      1/8” (3mm)
W > 1” (25mm)                            3/16” (5mm)




                                                WELDER’S HANDBOOK
                                                         Page 16 of 26
C.   UNACCEPTABLE FILLET WELD PROFILES




D.   ACCEPTABLE GROOVE WELD PROFILE IN BUTT JOINT




     Note: Reinforcement “R” shall not exceed 1/8 in. (3 mm).
                                              WELDER’S HANDBOOK
                                                       Page 17 of 26
E.   UNACCEPTABLE GROOVE WELD PROFILES IN BUTT
     JOINTS




                                   WELDER’S HANDBOOK
                                            Page 18 of 26
                  WELDING POSITIONS
A.   PLATE
     1.  Groove
         1.1 Flat Position (1G)




                     Plates Horizontal
          1.2   Horizontal Posiiton (2G)




                Plates vertical; axis of weld horizontal
          1.3   Vertical Position (3G)




                Plates vertical; axis of weld vertical

                                                WELDER’S HANDBOOK
                                                         Page 19 of 26
     1.4      Overhead Position (4G)




                    Plates Horizontal

2.   Fillet

     2.1      Flat Position (1F)

      Throat of weld vertical                           Axis of
                                                        weld
                                                        horizontal




     2.2      Horizontal Position (2F)

                                                   Axis of
                                                   weld
                                                   horizontal




     Note: One plate must be horizontal
                                          WELDER’S HANDBOOK
                                                   Page 20 of 26
        2.3    Vertical Position (3F)

                 Axis of weld vertical




        2.4    Overhead Position (4F)



Axis of weld
horizontal




                     Note: One plate must be horizontal.




                                            WELDER’S HANDBOOK
                                                     Page 21 of 26
B.   PIPE

     1.     Groove
            1.1 1G Rotated – pipe horizontal and rotated, weld flat
                 (+15O), deposit filler metal at or near the top.




                  Pipe horizontal and rotated. Weld flat (+15O).
                  Deposit filler metal at or near the top.

            1.2   2G – pipe or tube vertical and not rotated during
                  welding, weld horizontal (+15O).




                  Pipe or tube vertical and not rotated during welding.
                  Weld horizontal (+15O).


                                                WELDER’S HANDBOOK
                                                         Page 22 of 26
1.3   5G – pipe or tube horizontal fixed (+15O) and not
      rotated during welding. Weld flat, vertical and
      overhead.




      Pipe or tube horizontal fixed (+15OC) and not rotated
      during welding. Weld flat, vertical and overhead.

1.4   6G - pipe inclination fixed (45O +5O) and not rotated
      during welding.




      Pipe inclination fixed (45O +5O) and not rotated
      during welding.




                                     WELDER’S HANDBOOK
                                              Page 23 of 26
     1.5      6GR – test position for T, K, Y connections. Pipe
              inclination fixed (45O +5O), with restriction ring and
              not rotated during welding.
              Restriction
              Ring


      Test
      Weld




2.   Fillet

     2.1      1F ROTATED – flat position




                                              WELDER’S HANDBOOK
                                                       Page 24 of 26
2.2   2F FIXED - horizontal position




2.3   2F ROTATED – horizontal position




2.4   4F FIXED - overhead position




                                   WELDER’S HANDBOOK
                                            Page 25 of 26
2.5   5F FIXED – multiple position




                                     WELDER’S HANDBOOK
                                              Page 26 of 26

				
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