Page 205 - CITS - Fitter Trade Pactical - Volume - 2

FITTER - CITS

Job Sequence

TASK 1 : Oxy - acetylene flame setting
• Wear safety apparel

• Open the gas cylinders and adjust the gas pressures on the regulators
• Open the control valve of the acetylene gas in the blowpipe
• lgnite the flame by using a spark lighter.
Avoid using any other source of fire
• Adjust the acetylene flow till the black smoke goes away

• Open the oxygen gas till a proper round inner cone is established without any sound in the flame. This is
known as a neutral flame.
• Adust the oxidizing flame by increasing the oxygen gas (with sharp inner cone and little hissing sound)

• Set the neutral flame again and adust the carburizing flame by increasing the acetylene gas with the soft inner
cone covered with an outer feather without any sound
• Repeat the setting of the flames till you manage to set the flame without any backfire or flash-back

Flame extinguishing and stopping work
• Extinguish the flame by closing the acetylene valve first and then the oxygen valve
• Dip the blowpipe nozzle in water to cool down by opening a little oxygen gas

• Close the cylinder valves and release all the pressure from the line

TASK 2 : Fusion runs without filler rod in flat position by gas
• Check the size of the raw material.
• Mark and file to size.
• Mark the bead position as per drawing.
• Clean the surface

• Set the job piece on the welding table with the left edge raised about 15mm.
• Select and attach nozzle size 5 with a blowpipe (Indian Oxygen make)
• Set the acetylene and oxygen pressure at 0.15kg/cm2 on the regulators.
• Wear safety apparel and set the NEUTRAL flame.

• Hold the blowpipe in position with the job at the right edge with the nozzle angle 60° - 70° with the welding
line (marked with punches) nozzles angle 90° with the adjoining surface distance of the flame cone 1.5mm to
3.0mm from the surface, pointing leftward.
• Start heating and fusing the surface with a slight circular motion of the blowpipe.
• Move the blowpipe in a leftward direction keeping a uniform speed as you get local fusion (small round pool of
molten metal).
Avoid excessive concentration of heat. If the metal becomes too hot, lift the blowpipe momentarily
away from the molten pool.

Keep the molten pool in correct size by adjusting the rate of travel and the circular motion of the
blowpipe.
• Stop at the left edge and lift the blowpipe quickly.

• Extinguish the flame and cool the blowpipe in water.
• Clean the fused surface with a steel-wire brush and inspect the uniformity of fusion runs.

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CITS : C G & M - Fitter - Exercise 54