Hydro Test for SS,CS,Fiber Glass

Normal potable water should be fine, unless some additional specifications are given. (This might happen if the vessel is destined for some kind of ultra-clean service. There are also some services that specify oil rather than water as the test fluid.)

I agree potable water should be fine. The only concern I can think of off hand is the chlorine level in the water. You don't want a high chlorine level in stainless steel because you could introduce SCC during the test.

Sadly, I don't remember which standard talks about Cl levels in hydrotests.

As for the standard for the test, most plants in the US use API 570 and ASME B31.3 (for process piping). Normally, the standard that the pipe is designed to will specify the hydro test procedures.

Normally design parameters of process piping and vessels specify the hydro test requirements. Hydro test water temperature and chlorine contents are generally specified by the technology provider. for example in India Cl. level should not be more then 30ppm in the test water and temperature range is specified as ambient +/- 5°C OR 10°C or so.