API 510 - In-Service, Out-of-Service Clarification 1

[myname_earl]

Is there a solid way to determine if a vessel is out of service?

There is politicking in management right now as a vessel went over its 10-year internal interval by 34 days and maybe we could consider it out of service for stints like during two, 20-day TARs so we'd "gain" 40 days thus still having 6 days to remove from service again and complete the internal inspection. We didn't inspect it during these TARs and I'm going to assume the worst case is that they were flushed out but not thoroughly cleaned and not air-gapped.

Has anyone heard of this being valid or tried? I hate stretching gray areas and definitions but if this strategy is common, maybe it's worth considering.

 

[Louisiana Inspector]

API 510 section 6.5.1.4 answers your question.

6.5.1.4 For pressure vessels in noncontinuous service, the interval is based on the number of years of actual
service (vessel in operation) instead of calendar years, provided that when idled, the vessel is:

a) [highlight #FCE94F]isolated from the process fluids[/highlight], and

b) [highlight #FCE94F]not exposed to corrosive internal environments[/highlight] (e.g., inert gas purged or filled with noncorrosive
hydrocarbons). Vessels in noncontinuous service and not adequately protected from corrosive environments
may experience increased internal corrosion while idle. The corrosion rates should be carefully reviewed
before setting the internal or on-stream intervals

If you can Prove A and B then you can inspect at the actual years of service.

Also, you could look into performing an On-Stream in-lieu of an Internal Inspection if you meet the requirements of 6.5.2

 

[myname_earl]

Thank you - I apologize for asking a simple question from the book, I just do not have access at the moment.


God bless!