Checking for external pressure test conditions?

[Cryo88]

My equipment is designed according to section VIII div1 UG-28 for an external pressure of 10 bars. An external pressure pneumatic test will be done at 11 bars according to code.
Do I proceed to any further calculation to be sure that no problem occurs during pressure test? In other words, does the pneumatic test pressure be considered as the design pressure for UG-28 calculation, or does the calculation at design pressure provide sufficient margin to covers also test conditions?

Thank you for your help.

 

[Cryo88]

In my opinion, calculation at design pressure include safety coeeficient so that there is no risk during strength test.
My customer is not convinced and ask me to calculate with test pressure as design pressure.
Can anybody help me?

 

[vpl]

IMO, if your customer asked you do the calculation, do it and bill him.

Patricia Lougheed

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[Shmulik]

Does your equipment contain heads (ellipsoidal and torispherical) subjected to the external pressure?

UG-33(a)(1)(a): "For ellipsoidal and torispherical heads, the required thickness shall be the greater of the following: (a) the thickness computed by the procedure given in UG-32 for heads with pressure on the concave side using a design pressure 1.67 times the design pressure on the convex side".

UG-33 DOES NOT redefining your MAWP! The requirement of UG-33(a)(1)(a) is only additional requirement for HEAD (only) exposed to external press. to be designed to an assumed internal (concave) pressure that is 1.67 times the external press. Nothing is required to other pressure parts connected to that head, thus, it DOES NOT affect MAWP and test press.
Pneumatic test press. should be 1.1 times MAWP marked on vessel's name plate, regardless internal head calculations.