Page 214 - CITS - Fitter Trade Pactical - Volume - 2

FITTER - CITS

Job Sequence

TASK 1 : Single ‘V’ butt joint in flat position by arc welding

• Straight cut two 12mm thick plates by gas cutting as per drawing and grind them to size.
• Mark the bevel to 30o angle using bevel protractor in two plates.
• Punch witness marks
• Bevel the edges of each plate to 300 angle by gas cutting and file the root face as per drawing for edge
preparation single ‘V’ Butt of joint. (Fig 1)

Fig 1

• Clean the plates from dirt, water, oil grease, paint etc.
• Keep the plates inverted in the form of a butt joint with proper root gap.

• Maintain a distortion allowance of 1.5o on each side of the joint.
• Wear all protective clothings.
• Use a 3.15mm medium coated MS electrode and set 110 amperes current. In case of DC welding machine
connect the electrode cable to the negative terminal of the machine.
• Tack weld on the back side of the plates at the ends. The length of tack should be 20mm.
• De-slag the tack weld and clean.
• De-slag and clean the root run and inspect root penetration.
• Position the tack welded job on the table in flat position (the single V portion facing up )

• Deposit the root run and fill the crater as done for welding square butt joint.
• Take special care to maintain key hole to ensure proper melting of root face and root pentration.
• Deposit the second run/intermittent run using 4mm medium coated electrode and 150-160 ampere current,
short arc and proper weaving of the electrode. Avoid excessive weaving and ensure normal travel speed.
• Fill the crater wherever necessary.
• De-slag.
• Deposit the third run/covering run using the same parameter and technique used for 2nd run. Ensure a proper
reinforcement of 1 to 1.5mm and avoid undercut.
• Inspect for any surface weld defect.

TASK 2 : Fillet weld in open corner joint in flat position by arc welding
• Prepare job plates to size as per drawing.
• Clean the joining edges and surfaces of plates.
• Set the plates as an open corner joint with a root gap of 2.5 mm using an angle iron jig.

• Select correct polarity, if a DC generator is used.
• Tack the joint pieces at both ends using Ø 3.15 mm medium coated MS electrode and 100-110 amps current
from inside of the joint.

• Ensure safety apparels are worn. Use a proper method to control distortion.
• Clean the tacks, check alignment and reset the joint, if required.

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CITS : C G & M - Fitter - Exercise 54