Page 151 - CITS - Welder - Trade Practical

WELDER - CITS

EXERCISE 44 : Fusion welding of cast iron butt weld, cast
iron block 150 x 50 x 10mm- position flat

Objectives

At the end of this exercise you shall be able to
• prepare the edges of the plate to be welded
• set the job as per sketch

• select the nozzle and filler rod, set the gas pressures and flame for cast iron welding
• preheat the job by a blowpipe
• identify and use the flux
• manipulate the blowpipe and filler rod to get proper root penetration and fusion weld face
• take steps for post heating and slow cooling
• clean the joint and inspect for external weld defects.
Job Sequence

Maintain the angle of the blowpipe at 60° to 70° and give a circular motion to the blowpipe.
Deposit a root run with a 3mmø filler rod and the finishing run with a 5mmø filler rod. Dip the hot filler rod end into
the powdered bronze flux frequently.

In bronze welding of cast iron, the base is only heated to 650°C and it is not melted. So while depositing the root
run the surfaces of the joint is coated with a layer of filler metal for about 20mm along the joint, ensuring that it is
correctly bonded.
Then return to the starting point and add sufficient filler metal to produce a satisfactory weld. This method is
repeated continuously until the root run is completed. Ensure root penetration by the filler metal and fusion
between consecutive bronze filler metal deposits.
Weld similarly the 2nd run by using 5mmø filler rod dipped in flux with a soft oxidizing flame and get 1.5mm
reinforcement and good bead up to the end of the joint.
Clean the bead and remove the flux residue on both sides of the joint.
Inspect the joint for weld defects like porosity, incomplete penetration etc.
• Clean the surfaces of the job piece thoroughly by a wire brush and remove the skin of the plate near the joining
surfaces by grinding
• Bevel the edges for butt welding at an angle of 45” by grinding
• Deburr the edges by filing and round the comers.
• Set the job pieces with a 2-3 mm root gap and keep it on the fire-brick

• Select nozzle No. 10 and fix in the blowpipe
• Set the neutral flame and preheat the surfaces of both plates to a dull red colour
• Select 6mme super silicon cast iron filler rod and cast iron flux
• Dip the hot end of the filler rod into the powdered flux and keep it ready for use at the time of tacking and
welding

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CITS : C G & M - Welder - Exercise 44