Page 216 - CITS - Welder - Trade Practical

WELDER - CITS

Skill Sequence

Make single ‘V’ butt joint on M.S. (10mm. thick plate) in horizontal
position by GMAW

Objectives: At the end of this exercise you shall be able to
• make single ‘V’ butt joint on M.S. (10mm. thick plate) in horizontal position by GMAW.

Setting and tacking of the Tee joint in horizontal position : Clean the base metal surface along the welding
line with a wire brush.

Place the horizontal plate on the table and the vertical plate at the centre of the horizontal plate to form an inverted
T joint.
Tack weld the two plates at the ends.

Set the welding conditions: Adjust the gas flow rate to 8 to 10 LPM.
Cut off the wire end so that the distance between the tip and base metal is about 8 to 10mm.
Adjust the welding current to about 90 to 100A for 0.8mm filler wire used in Dip Transfer.
Adjust the welding Arc voltage to about 19 to 20V.
Generate an arc: Generate an arc at about 10mm ahead of the starting and return to the start point to avoid
excessive reinforcement at the start and starting porosity.
Keep the distance (stick-out) of about 8 to 10mm between the contact tip and base metal.
Hold the torch at about 70 to 800 against the welding direction and at 450 against the base metal surface.
The wire tip should point at the root for the root run.

Depositing the root run: Move the torch from left to right (backhand technique) taking care to point the tip at the
leading end of the weld puddle.
Fuse both base metals evenly.
Do not weave the torch. Use stringer bead technique only.

Fill the crater: Repeat it until the level of the crater becomes the same as the bead reinforcement.
Clean the scales and other non-metallic materials and spatters from the root run and the joint.
Deposit the 2nd run using stringer bead technique such that the bead covers two thirds of the root run deposit
and the bottom plate.
Clean the bead and the plate surface with carbon steel wire brush.
Deposit the 3rd run using stringer bead technique such that the bead covers the root run, two thirds of 2nd run
and the vertical plate member.
In addition the leg length ‘L’ has to be maintained as 8mm.
The torch angle between the plates has to be changed.
The torch angles are to be changed for 2nd and 3rd run in order to deposit the weld metal at proper places so that
the correct leg length can be obtained. This also helps to avoid defects like overlap, undercut, insufficient throat
thickness etc.
Ensure uniform travel speed for the torch for all the 3 runs to get proper bead profile and appearance.

Clean the joint after completion of the 3rd run.
As and when required, the torch nozzle is to be cleaned with anti-spatter spray / gel during welding.

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CITS : C G & M - Welder - Exercise 53