Criteria for Limiting Hydro Test Stress in COMPRESS
ASME Section VIII Division 1 does not require stresses to be limited during hydrostatic test. COMPRESS provides the option to remove the test stress calculation. This is specified on the Testing tab of the Set Mode Options dialog. To remove the test stress calculations, uncheck the “Calculate hydrotest stress” option.
The allowable stresses for the test condition are established as follows:
(1) The designer specifies the percentage of yield stress to be permitted at test. This value is directly used for Pm stresses (general primary membrane tensile stress).
(2) COMPRESS applies factor 1.5 for local combined stresses as indicated in Section VIII Division 1, UG-23(c).
This approach leads to the case where the allowable stresses will be different for nozzles and shells of the same material. This is because only (1) above is used for the shell and both (1) and (2) are applicable for the nozzle. For nozzles, the yield stress is taken as that of the parent component.
The determination of stresses in the shell at the nozzle opening are found using the method in Division 2, Part 4.5. COMPRESS uses Part 4.5 as it provides a basis to determine the local stress in the shell at the nozzle opening.
For further information, please see the Hydro Test section in our Support Center.
If you don’t have software that performs hydro test calculations, it’s time to explore the benefits of COMPRESS. Find out more by emailing firstname.lastname@example.org or calling (941) 927-2670.