Page 278 - CITS - Welder - Trade Practical

WELDER - CITS

Job Sequence
• Prepare the plates to size (i.e 150 x 50 x 10mm) using gas cutting, grinding and filing.
• Clean the base metal surface along the welding line with a carbon steel wire brush.
• Set the plates in the form of an inverted “T”.

• Wear all protective devices.
• Tack weld the 2 plates, keeping the T joint in horizontal position.
• Set the welding parameters as done in earlier exercises.
• Strike the arc keeping proper angles for the torch.
• Deposit the root run without weaving and ensure proper penetration and fill the crater.

• Check for defects like overlap, undercut, porosity and check for correct leg size and throat thickness.
• Visual inspection: slight convexity, uniform width, uniform ripples and free from under cut at the toes of
the weld indicate a smooth

Skill Sequence

Make Tee Joint on Aluminium sheet 2mm thick in down
vertical positions by GTAW

Objectives: At the end of this exercise you shall be able to
• make Tee Joint on Aluminium sheet 2mm thick in down vertical positions 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 ∅ 2.4 Tungsten electrode with 160-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 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 Corner/fillet weld and ensure: comer
- 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 69