Regarding the relationship between pipeline heat treatment and hydrostatic pressure?
Thread Content
There is currently a pipeline for transporting waste alkali, made of carbon steel. It has been replaced due to corrosion, and in order to prevent stress corrosion, it was decided to carry out heat treatment on the welds. Normally, heat treatment should be performed before pressurizing the pipeline; but is it possible to carry out heat treatment after pressurization?
The poster mentioned that a hydrostatic test should be carried out after heat treatment. Generally, heat treatment is only used to relieve stress in the welds, so it does not cause any damage to them. However, procedurally speaking, the pressure test is the final inspection step after the pipeline construction is completed. However, sometimes improper control of the heat treatment temperature can cause damage to the welds; therefore, heat treatment after testing is not recommended. Just as 100% non-destructive testing can sometimes replace hydrotesting, it does not mean that hydrotesting is no longer necessary after such testing (sometimes leaks are still detected during hydrotesting of pipes that have passed the non-destructive testing).
No, the order is important; if done this way, a hydrostatic test is also required