ASME hydraulic test pressures 1

[Technopriest]

Good morning to you all.
I'm working on a filter that has to be built according to ASME code. We are from Italy and we are used to PED Code, so we are having a little trouble.
We usually make two set of calculations; one for Design conditions and the other one for Hydraulic test conditions. PED code, however, allows us to use an higher allowable stress for alloys under hydraulic test conditions.

My questions are:
1) Are hydraulic test calculations mandatory for ASME code vessels?
2) If 1) is "yes", do we need to make Hydraulic test calculations with standard allowable stresses or there is some variations? (I'm considering SA 240 TP 316 H.S. material, and design temperature will be 120°C while Hydraulic Test temperature will be 20°C- so, if I understand correctly, allowable stresses should be the same..)

Any answer would be greatly appreciated! We are not willing to avoid code mandatory documentation, but we are not willing to design a vessel for a far greater (1,66x!) pressure if we are allowed not to.


Che Dio ce la mandi buona, o almeno ce la mandi- Massimiliano Eusebi

 

[TomBarsh]

ASME Section VIII Division 1 does not specify any limit on stresses during hydrostatic test (ie: there is no allowable stress specified). In fact, this Division does not even require that stresses be calculated for test condition. UG-99(d) and (g) address the criteria by which the test should be judged (essentially, no leaks and no visible permanent deformation).

ASME Section VIII Division 2 specifies allowable stresses at test in paragraph AD-151.1 as below, which gets a bit tricky. Pm is general primary membrane and Pb is primary bending

(a) Pm <= 0.9 * Sy

(b1) Pm+Pb <= 1.35*Sy for Pm <= 2/3*Sy

(b2) Pm+Pb <= 2.2*Sy-1.5*Pm for 2/3*Sy < Pm <= 0.8*Sy

 

[TomBarsh]

"...design a vessel for a far greater (1,66x!) pressure"

I am not certain where you get the factor 1.66 times design pressure (or MAWP). Is this from PED?

Current ASME Section VIII Div 1 requires testing at 1.3 x MAWP (or design pressure) per UG-99(b). Division 2 has factor 1.25.

 

[Technopriest]

I'm going on memory, now (i'll check code later on). Value 1,66 comes from the formula
HTP = DP * 1,3 * SHT/SD
Where:
HTP: hydraulic test pressure
DP: design pressure
SHT: allowable stresses at hydraulic test temperature
SD: allowable stresses at design conditions

Even if we have ASME SA 240 TP 316L as main vessel material, there is a very important flange made out of SA 193 Gr. B8- and this material DO change allowable stresses at 20°C and at 120°C. Hence the 1,66 multiplier.

Thanks a lot, Tombarsh. I'll try to work out on what you said to me.


Che Dio ce la mandi buona, o almeno ce la mandi- Massimiliano Eusebi

 

[Technopriest]

I mean, the flange is in SA 182, the bolts on it are SA 193 Gr. B8. Sorry for the mistake.

Che Dio ce la mandi buona, o almeno ce la mandi- Massimiliano Eusebi