Page 240 - CITS - Welder - Trade Practical

WELDER - CITS

- Avoid under cut
- Ensure the edges of the plate is not melted off due to excessive weaving
- Ensure there is no undercut at the other toe of the lap weld on plate
Note: Wear protective clothing.

• Tack-weld on both ends.
• Set the lap joint in a flat position.
Note: Ensure an electrode angle of 45° with the fillet corner and 80° with the welding line.
• Remove the slag with a chipping hammer and clean with a wire brush.

• Use tongs to hold the job.
• Wear chipping goggle for the protection of eyes.
• Deposit the final covering run with a weave motion using a 4.00 mm dia. Medium coated M.S. electrode
with150-160amps welding current.

Note: Prevent the upper edge of the plate from melting off.
• Remove the slag from the final weld and clean thoroughly.
Note: Use a weld gauge to check the fillet size.
• Inspect the lap fillet weld for surface defects and size.

Skill Sequence

Lap joint on S.S. sheet 2 mm thick by GMAW

Objectives: At the end of this exercise you shall be able to
• lap joint on S.S. sheet 2mm thick by GMAW.

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 current for tacking.

Set the joint in a flat position using angle iron.
Welding the lap fillet joint in flat position
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.
Avoid side-to-side movement of the electrode.
Deslag and clean the root bead thoroughly.
Use the same wire angle as was used for the root bead.
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:
- It has equal leg length with slight convexity
- The upper edge of the plate has not melted off
- It is free from surface defects.

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CITS : C G & M - Welder - Exercise 58(B)