Clarification on hydro test pressure

[vinothhsvk]

Hi All,

My client specification says, that the hydro test pressure shall be maximum of ASME SEC VIII DIV-1. but below my report shows some values for different cases(UG-99, UG-99(36), UG-99(C)). In this case, Can i take UG-99(C) as hydro test pressure?? kindly advise to me.


Pressure per UG99b = 1.30 * M.A.W.P. * Sa/S 63.631 barg
Pressure per UG99b[36] = 1.30 * Design Pres * Sa/S 46.576 barg
Pressure per UG99c = 1.30 * M.A.P. - Head(Hyd) 67.204 barg
Pressure per UG100 = 1.10 * M.A.W.P. * Sa/S 53.841 barg
Pressure per PED = max(1.43*DP, 1.25*DP*ratio) 49.875 barg
Pressure per App 27-4 = 1.30 * M.A.W.P. * Sa/S 63.631 barg

 

[Geoff13]

The UG-99(b) pressure is the minimum Code test. It can be based on either the vessel MAWP, or if that hasn't been calculated then the design pressure (per footnote 36). Since you've calculated MAWP I would say this rules out what you've called the UG-99(b)[36] test pressure.

UG-99(c) is generally a higher test pressure determined from detailed calculations on every part. When the pressure is higher, so is the risk. Thus the requirement for agreement by both the User and the Manufacturer. In your case there's only a 5% pressure increase, so not much added risk.

For your vessel you seem to be correct that UG-99(c) is the maximum Code test pressure.


You also list three more pressures. Since UG-100 is pneumatic testing, it's obviously not relevant. Appendix 27-4 is only for glass lined, which you didn't list as a vessel condition (I read 27-4 to limit the test pressure to MAWP, though I've never been involved with an App 27 vesssel). I've never worked with PED so no comment on that value, however design philosphy and test philosphy are tightly linked, and thus it would be very bad practice to pull a test pressure from a source other than Division 1.

 

[vinothhsvk]

Dear Geoff13,
You told that my seem to be correct that UG-99(c) is the maximum Code test pressure. but, my client commented that to follow UG-99(b). Its ok or not??

 

[Geoff13]

It is always acceptable to use the UG-99(b) test pressure.

Use of the UG-99(c) test pressure is optional. The first sentence in UG-99(c) says "... may be used ...".

 

[SnTMan]

Usually, not always, a good idea to do what the client asks

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

I prefer "UG-99(c) may be used only by agreement between the user and the Manufacturer".

Regards
r6155