Page 27 - CITS - Welder - Trade Practical

WELDER - CITS

Job Sequence

Making straight cuts
• Wear all safety clothing.
• Set the gas welding plant with a cutting blowpipe, and cutting oxygen regulator.
• Fit the correct cutting nozzle according to the thickness of the metal to be cut (for M.S. plate 10mm thickness
use 1.2mm dia. orifice cutting nozzle)
• Adjust both oxygen and acetylene gas pressure according to the cutting nozzle size. (Oxygen 1.6 kg/sq.cm
and acetylene 0.15 kg/sq.cm)
Note: While adjusting the pressure, keep the cutting blowpipe valves open.
• Take 200×150×10 thick plate, clean, mark and punch the straight lines on the plate 25mm apart.
• Set the neutral flame.
• Wear the gas welding goggles.

• Hold the blowpipe at an angle of 90° between the line of cut and the cutting nozzle axis and between the
nozzle and the surface of the plate.
• Heat one end of the punched line up to cherry red-hot condition.

• Keep the distance between the work piece and the tip of the nozzle about 5mm.
• Place the preheat cone approximate 1.6mm above the plate.
• Move the flame in circle a little larger than the tip size. When metal is heated to Cherry red, move the tip to the
edge of the plate.

• Operate the cutting oxygen lever immediately and move the torch slowly along cutting direction.
• Maintain correct torch speed and distance between the plate surface and the nozzle up to the end of the cut.
• If long plates are to be cut, to get a good straight gas cut surface, clamp a straight edged flat parallel to the
line of cut and use a spade guide attached to the cutting torch. Move the torch uniformly along the clamped flat
and pressing the spade guide against the flat.
• On completion of the cut release the cutting oxygen lever and shut off the flame.
• Clean the cut surface by wire brush after chipping off any slag sticking to the cut edge

Skill Sequence

Gas cutting

Objectives: At the end of this exercise, you shall be able to
• set the gas cutting plant

• cut the material to the required size.

Setting the gas cutting plant: Set the oxy-acetylene gas cutting plant in the same way as was done for welding
and connect the cutting blowpipe in the place of the welding blowpipe. (Fig 1) Also change the oxygen welding
regulator with oxygen cutting regulator.
Setting the job for straight line cutting (Fig 2): Mark and punch 7 straight lines on the plate 15 mm apart for a
straight line cut and 3 lines 25mm apart for bevel cutting on other edge.
Set the job on the cutting table so that the parting piece is free to fall.
Ensure that the underside of the cutting line is clear and no combustible materials are lying nearby.

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CITS : C G & M - Welder - Exercise 04