Page 264 - CITS - Welder - Trade Practical
P. 264
WELDER - CITS
Skill Sequence
Construct Lap joint on MS sheet 1.6 mm in Vertical position
by GTAW
Objectives: At the end of this exercise you shall be able to
• construct Lap joint on MS sheet 1.6 mm in Vertical position by GTAW.
Setting and tacking the lap joint
Set the lap joint with an overlap of 25mm.
The overlap may vary based on the plate thickness.
Tack-weld on both ends. Ensure the 2 lapping sur-faces are perfectly cleaned and they contact each other
properly. Use a current for tacking.
Set the joint in a flat position using angle iron.
Welding the lap fillet joint in flat position
Deposit root run with a 100-110 amp current.
Maintain 80° angle to the line of the weld and 45° between the weld faces.
Maintain a short arc to get uniform fusion and root penetration.
Note : Avoid side-to-side movement of the electrode.
Deslag and clean the root bead thoroughly.
Deposit the final covering run and 160 amp current.
Give side-to-side movement to the electrode not more than 2.5 times its dia.
Use the same electrode angle as was used for the root bead.
Note :Prevent the upper edge of the plate from melting off by not allowing the arc to concentrate
more on the upper edge.
Remove the slag with a chipping hammer.
Clean the weld with a steel wire brush.
Inspect the lap fillet weld and ensure:
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CITS : C G & M - Welder - Exercise 64