Page 75 - CITS - Welder - Trade Practical

WELDER - CITS

Job Sequence

• Cut the MS plate 10mm thick to size (2 Nos.).
• Bevel the edges as per drawing.
• Both plates will have 30 to 35° bevel angle and 1.5mm root face and with no burr at the edges.

• Using spacers maintain a uniform gap of 2mm throughout and tack weld the plates.
• Preset the plates to 177° on the root side of the joint.
• Set the tack welded joint in vertical position
• Use ø3.15mm MS electrode and DCEN polarity for DC welding.
• Deposit the root run starting from bottom of the plate upward and maintain a uniform root penetration.

• Use short arc.
• Remove slag etc. and clean the weld with wire brush.
• Use ø4mm MS electrode and 150-amp current.
• Deposit 2nd, 3rd run using proper weaving technique and complete the weld in vertical position.

• Check the proper root penetration and other external weld defects.
• Rectify the defects whenever possible.

Skill Sequence

Single ‘V’ butt joint on MS plate of 10mm thick in vertical

position

Objectives: At the end of this exercise you shall be able to
• prepare and weld single ‘V’ butt joint on MS plate of 10mm thick in vertical position.

Preparation of pieces
Cut and bevel the edges to an angle of 30 to 35° by using oxy-acetylene cutting.

Grind the bevel edges to remove oxides, and get smoothness.
Note: Use goggles while cutting and grinding.
Prepare a 1.5mm root face throughout the length by filing.
Setting and tacking of single ‘V’ butt joint
Keep the bevel edges parallel with the 2.5mm root gap. The 2.5mm thick spacers are used to get a uniform and
parallel root gap.
Tack-weld on both ends with correct alignment and presetting of 3° to control distortion. (Fig 1) i.e. on the root side
the angle between the plates should be 177°.
Position the joint in vertical using the weld positioner.
Deposition of weld beads
Deposit the root run using a 3.15 mm dia. M.S. electrode and 110 amps current with a slight sideways movement
of the electrode. (Fig 2)
Note: Ensure a keyhole throughout the root run.
The angle of the electrode in the holder should be 120° so that it is convenient to hold the electrode at 80° to the
line of weld.

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CITS : C G & M - Welder - Exercise 11