According to ASME B31.3, the test pressure should be
PT= 1.5 x ST/S
where
PT = test pressure
ST = allowable stress @ test temperature
S = allowable stress @ design temperature
This ratio shall fulfill 1 <= ST/S < 6.5.
In Europe, in accordance with the pressure equipment directive, PT = max of 1.43xPD or 1.25 x ST/SxPD.
with PD = design pressure
A sufficient supported system that passed the sustained stress check will normally not show overstressed nodes during hydrotest. Of course the restraint loads are often higher than in any of the operating cases and must be taken into account when designing the related civil structures.
All the best,
Veit Bockemühl
www.esn-gmbh.com www.surgeanalysis.com