Page 228 - CITS - Welder - Trade Practical

WELDER - CITS

EXERCISE 55 : Make single v butt joint on m.s. (10 mm.

thick plate) in vertical position by GMAW

Objectives

At the end of this exercise you shall be able to
• prepare the plates with necessary bevelling and root face
• preset the plates in alignment in vertical plane with necessary root gap and tack weld
• deposit the root run with root penetration and uniform melting of both root faces of the joint
• set up the GMAW machine and set welding parameters.

Job Sequence

- Cut the plate by using hacksaw cutting as per drawing
- Clean the joining edges and surface of the plates
- Adjust the power source and wire feeder to obtain 18 to 19 volts and 90 and 100 amperes, gas flow 8-10 LPM.

- Thoroughly clean the pieces to be joined. Pay particular attention to the top of the plate, the side walls of the
groove and the underside of the joint. Grind or file a1.5 mm root face on each beveled edge
- Tack the pieces together and position

- Put spacers under the plate so that you don’t weld the plate to your table
- Hold the gun perpendicular to the joint and strike the arc at the tack. Move the torch from left to right end of the
joint i.e use back hand technique. Weave the gun from side to side. When the gun is in the center of the joint,
watch the arc very closely. By concentrating the arc on the leading edge of the puddle, you can cause the bead
to penetrate through the joint and fuse both root faces. If you bring the arc too far down in the puddle, the wire
will go through the joint and the arc will become very erratic. If you allow the arc to go too far upon the puddle,
your penetration will decrease and you will not penetrate the joint. Practice will help you use the arc to control
the flow of the weld puddle

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CITS : C G & M - Welder - Exercise 54(C)