No replies to this topic

[Root]

Hi all, according to ASME VIII DivI, UG 99 is applicable for all pressure vessels for hydrostatic test 1.3 at design pressure and UG 100 for pnumatic test at 1.1 of maximum operating pressure. Interpretation is very clear in para B ( UG 99), my question is about once the vessel is manufactured in workshop and hydro tested, stamped then why we need again hydro test after maintenance even their is no head or shell opening during the maintenance. Pneumatic test at working pressure not enough instead of hydro test.particularly columns (like glycol cont actors and three phase separators). Can any one explain it further. thanks Toor