Page 49 - CITS - Welder - Trade Practical

WELDER - CITS

Job Sequence

• Prepare job plates to size as per drawing.
• Clean the joining edges and surfaces of plates.
• Set the plates as an open corner joint with a root gap of 2.5 mm using an angle iron jig.

• Select DCEN polarity, if a DC generator is used.
• Tack the joint pieces at both ends using ø 3.15 mm medium coated MS electrode and 100-110 amps current
at the inside of the joint.

• Ensure safety apparels are worn. Use a proper method to control distortion.
• Clean the tacks, check alignment and reset the joint, if required.
• Set the joint on the welding table in a flat position.
• Deposit root run in the joint by forming a keyhole and obtain complete penetration.
• Deslag and clean the root run and inspect root penetration.

Ensure the crown of penetration is not more than 1.6 mm in height.
• Grind and dress the face of the root run, if required.
• Set the welding current 160 amps for 4mm ø medium coated M.S. electrode.

• Deposit an intermediate layer i.e. second run over the root run with slight weaving motion using 4mmø
electrode.
• Clean the intermediate layer thoroughly and inspect for faults. Rectify the defects, if any.

• Deposit the final layer to the weld size using the same current setting, electrode and weaving motion as used
for the second layer.
• Clean the final layer for inspection.
• Inspect the corner fillet weld:

– To ensure uniform and correct reinforcement
– To ensure that the weld face is free from porosity, Slag inclusion, unfilled crater, overlap and edge of Plate
melted off/insufficient throat thickness.

Skill Sequence

Open corner joint on MS plate 10mm thick in flat position

Objectives: At the end of this exercise you shall be able to
• prepare and weld corner joint on MS plate 10mm thick in flat position.

Setting and tacking plate pieces for open corner joint (Fig 1)
Set the plates as an open corner joint on the table with parallel root gap of 2.5mm throughout the joint. The angle
between the plates is kept at 87° to control the distortion.
The angular distortion is normally taken as 1° per run.
Check the alignment of the joint with a try square. (Fig 1)
Another method to control distortion is, set the angle at 90° and use a right-angled iron fixture to minimize the
distortion.(Fig 3)

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CITS : C G & M - Welder - Exercise 6