Page 110 - CITS - Welder - Trade Practical

WELDER - CITS

EXERCISE 20 : Square butt and lap joint on M.S. sheet

2mm thick by brazing in flat position (OAW)

Objectives

At the end of this exercise you shall be able to
• braze an M.S. square butt joint using oxidizing flame and brazing filler rod and flux
• remove the surface oxide and other impurities with wire wool
• select nozzle, filler rod, flux and flame for brazing
• clean the joint and inspect for surface defects.

Job Sequence

• Cut the sheets as per drawing and file the edges to be joined square.
• Clean the joint area.

• Set the sheets as a square butt joint without root gap
• Select nozzle, filler rod, gas pressures, flux.
• Set oxidizing flame.
• Use leftward technique.

• Preheat the sheets and joint area to about 800°C.
• Dip the hot filler rod in flux and melt the filler rod into the joint ensuring proper wetting conditions.
• Avoid application of too much heat into the joint.
• Finish the joint in one run only.

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