PRE HEAT TREATMENT

Preheating involves heating the base metal, either in its entirely or just the region surrounding the joint, to a specific desired temperature, called preheat temperature, prior to welding.

POST WELD HEAT TREATMENT

Post Weld Heat Treatment (PWHT) is a controlled process in which a material that been welded is reheated to a temperature below its lower critical transformation temperature, and then it is held at that temperature for a specified amount of time.

STRESS RELIEVING

By the time it’s complete, the welding process can leave a large number of residual stresses in a material, which can lead to an increased potential for stress corrosion and hydrogen induced cracking. PWHT can be used to release these residual stresses and reduce this potential. This process involves heating the material to a specific temperature and then gradually cooling it.