Hydrostatic test vs Design by Analysis

[Mm.Kaiser]

Dear Friends,
As you know, in VIII-2 part5 there isn't a clear rule to consider Hydrostatic test in Design of equipment.
But i am working on an equipment which base of design is on Hydrostatic test condition and Design condition is not critical.
Is it possible for me to use Part4 Criteria for Hydrostatic test FEA according to this paragraph in part5?:

5.2.2.2: Stress Categorization ..... Stress limits for the pressure test condition are covered in paragraph 4.1.6.2.

Best Regards

 

[GenB]

Are you referring to Hydrostatic proof testing?

 

[TGS4]

Please describe your situation. Also, see discussion in thread

http://www.eng-tips.com/viewthread.cfm?qid=32906.

 

[Mm.Kaiser]

My situation is so:
Equipment is a part of huge piping system (Insulating Joint) which:
Design pressure= Dp
Test pressure= 1.5*Dp + Bending force +Torsion moment

Although in design condition there is no intensive stress but in Hydrostatic test condition, we should consider more thickness to admit the Type test requirements.
I want to know if i can use Part4 criteria (paragraph 4.1.6.2) in Finite element analysis of that equipment. The question is because of that i remember you(TGS4) told me that in part5 there isn't load combination for hydrotest criteria and we should not design our problems according to that load.
Quote:

The Code Committee is currently evaluating whether or not the hydrostatic test condition should be included in an evaluation, and what the appropriate stress limits (or load factors) would be​

Kind Regards.

 

[TGS4]

My prior advice still holds. One should not have a design governed by the hydrostatic test condition, but rather the design condition.

You could use an FEA to evaluate 4.1.6.2, but you would best be advised that the stress categorizations listed therein are ones where it would be more appropriate to use hand calculations.

There had been no progress on this item that will make the 2015 edition of the code, but I am hopeful for it to make it into the 2017 edition.