Page 101 - CITS - Welder - Trade Practical

WELDER - CITS

Skill Sequence

While tack welding plates A and B for the Tee joint the angle between them is to be kept at 91º initially (i.e a
distortion allowance of 1º per run) or Tee fillet joints distortion allowance is recommended.
Since GMAW process does not have the ability to remove many impurities, it is very important to clean the mill
scale, rust, paint, oil or grease from the plate surface.
For welding the joints in flat (downhand) position it is convenient to use the channel to position the joints. This will
permit the tack welded job to be kept at 45º angle with the horizontal plane.

The gun is held perpendicular to the joint at angle of 5 to 15 degree forward to the direction of travel.
The torch movement at the edge of the top plate of the Tee joint should be so controlled that the edge is not
melted off. Also the torch has to be paused when reaching the bottom toe of the weld for a short period so that
the undercut, if developed, at toe is properly filled with filler metal.
Maintain a uniform travel speed for the torch to get the required bead reinforcement, height and appearance.
Use the anti spatter spray as and when the torch nozzle gets clogged with weld spatters. Note that if this is not
done, the wire feed may be irregular causing unstabilised arc and the Carbon-di-oxide gas flow will not be uniform
causing atmospheric contamination of the weld and porosity.

84

CITS : C G & M - Welder - Exercise 17