Page 274 - CITS - Welder - Trade Practical

WELDER - CITS

• Avoid under cut

• Ensure the edges of the plate are not melted off due to excessive weaving.
• Ensure there is no undercut at the toe of the weld on plate
• 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 Corner joint on Aluminium sheet 2 mm thick in down

Vertical positions by GTAW

Objectives: At the end of this exercise you shall be able to
• make Corner joint on Aluminium sheet 2 mm thick in down Vertical positions by GTAW.

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 corner fillet joint in flat position
Deposit root run with ∅ 2.4 Tungsten electrode 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.

Note : Avoid side-to-side movement of the electrode.
Deslag and clean the root bead thoroughly.
Deposit the final covering run with a 4mmø medium coated MS electrode 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