Page 298 - CITS - Welder - Trade Practical

WELDER - CITS

• Tack-weld on both ends.
• Set the lap joint in a flat position.
Note: Ensure an electrode angle of 45° with the fillet corner and 80° with the welding line.
• Remove the slag with a chipping hammer and clean with a wire brush.
• Use tongs to hold the job.

• Wear chipping goggle for the protection of eyes.
• Deposit the final covering run with a weave motion using coated M.S. electrode with150-160amps welding
current.

Note: Prevent the upper edge of the plate from melting off.
• Remove the slag from the final weld and clean thoroughly.
Note: Use a weld gauge to check the fillet size.
• Inspect the lap fillet weld for surface defects and size.

Skill Sequence

Plan & perform Root pass welding of M. S schedule

40pipes by GTA Welding up to 6G Positions

Objectives: At the end of this exercise you shall be able to
• plan & perform Root pass welding of M. S schedule 40pipes by GTA Welding up to 6G Positions.

Setting and tacking the butt joint (Fig 1)
Set the butt joint with an overlap of 25mm.
The overlap may vary based on the plate thickness.
Tack-weld on both ends. (Fig 1) Ensure the adjacent sur-faces are perfectly cleaned and they contact each
other properly. Use a 120-amp current for tacking.
Set the joint in a flat position using angle iron (Fig 2).
Welding the lap fillet joint in flat position
Deposit root run with with 100-110 amp current.
Maintain 80° angle to the line of the weld and 45° between the weld faces. (Fig 2)
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 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 butt fillet weld (Fig 3) and ensure:
• It has equal leg length with slight convexity
• The upper edge of the plate has not melted off
• it is free from surface defects.

281

CITS : C G & M - Welder - Exercise 76