Welding Inspection & Metallurgy API ICP Self Study Notes

10.6 POST-WELD HEAT TREATMENT
Post-weld heat treatment (PWHT) produces both mechanical and
metallurgical effects in carbon and low-alloy steels that will vary widely
depending on the composition of the steel, its past thermal history, the
temperature and duration of the PWHT and heating and cooling rates
employed during the PWHT. The need for PWHT is dependent on many
factors ncluding;
• chemistry of the metal,
• thickness of the parts being joined,
• joint design,
• welding processes and
• service or process conditions.