Tank Re-Rate & Joint efficiency

[Water_Guy]

In a re-rate scenario, the original fabrication documents did not indicate that the welds were x-rayed. As a result an efficiency of 0.70 was used to determine the current retirement thickness. Is is allowed to now perform a spot or full x-ray and then to use either a joint efficiency of 0.85 or 1.00 to achieve a higher retirement shell thickness?

 

[jte]

Hi Bill-

Stating things like code of construction and location (Jurisdictional rules can be important) are quite useful when posting questions.

It seems that your query could be for an ASME Section VIII Division 1 pressure vessel. Maybe it's called a "tank", but probably not an atmospheric storage tank. If that's the case, I'll suggest that you re-post your question, along with far more detail along the lines of what I said above, in forum794. [If you did mean to post in a tank forum, then add the code of construction and location info to this thread.]

When you've posted there, "red flag" this thread by clicking on the little red flag to the right and add a comment to the effect of "reposted to the B&PV forum, please delete this one" so that you won't be cross-posting.

 

[JStephen]

For an API-650 tank, refer to API-653-4.3.3.1, where E is defined as "the original joint efficiency" for the tank. Note that away from welds, a higher value may be used.
If you start radiographing after the fact, the problem is that you don't know who welded which weld, so you can't just shoot a few shots and duplicate the original construction of a spot-radiographed tank.

 

[chicopee]

Much more info. about the tank would helpful.