Page 248 - CITS - Welder - Trade Practical

WELDER - CITS

Note: Wear protective clothing.
• Tack-weld on both ends.
• Set the lap joint in a flat position.
• Deposit root run by M.S. electrode with 100-110 amps current.
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 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

Fillet T joint on aluminium plate. 6 mm thick by GMAW

Objectives: At the end of this exercise you shall be able to
• fillet T joint on aluminium plate. 6 mm 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 a 110 amp 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 with 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.
Avoid side-to-side movement of the electrode.
Deslag and clean the root bead thoroughly.

Deposit the final covering run with a 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.
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 ‘T’ 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 59(B)