Hydrostatic Re-test Requirement

[MPD]

We are using pressure vessels with nitrogen gas to 1000 psig. The design limit is 5,000 psig. The vessel was originally proof tested hydrostatically to 2,000 (cycled 1,000 times), then the pressure was increased until it failed at 8,000 psig. This was in 1971. What are the current applicable codes governing hydrostatic re-test requirements? I'm looking for some guidance on this. Thank you.

 

[metengr]

For in-service vessels, the National Board Inspection Code (NBIC), NB-23 is applicable. Just a brief note; the NBIC will require you to follow the design and inspection requirements of the original code of construction.