• Oxy-Acetylene is a Fusion welding process.
  • The joint edges are heated until the metals melt.
  • The molten metals join and fuse.
  • Oxidation is prevented by the envelope of products of combustion.

1. Acetylene

Acetylene would explode if directly compressed. Instead cylinders are filled with
porous acetone which can absorb 25times the amount of acetylene. This is known as
dissolved acetylene.

2. Safety

Colour Coding

The gas cylinders are colour coded for safety as follows:

Oxy-Acetylene welding safety colour coding

Flashback Arrestors

Flashback arrestors are fitted to the regulators to prevent the feedback of flame through the hose.


  • There are 2 gauges on each cylinder.
  • The low pressure gauge shows supply in the torch.
  • The high pressure gauge shows pressure in cylinder.

3. Flames