Although certain parts of a plumbing system made using different materials (especially the pipes), the procedure for hydrostatic testing is pretty simple.
When a part of your plumbing system is tested, the technicians will first seal it and then fill it with an incompressible liquid such as water or oil. For systems that may suffer damage from the use of such liquids, the technicians may use other liquids that are more suitable to the plumbing section.
After the section has is sealed and filled, the technicians will subject it to a certain amount of pressure for a certain amount of time. Different materials subjected to different pressures depending on their pressure rating and the current pressure testing laws in effect.
Generally, most plumbing systems subjected to pressures above 1.25 times their ratings for about two hours.
This pressurization causes the plumbing section to expand and the technicians take note of the pressure readings. The technicians will also physically inspect the plumbing system and check for any shape distortion and leaks.
To make the detection of leaks easier, the incompressible liquid used to carry out the hydrostatic pressure test may be dyed.
Once the tests complete and the results recorded, the liquid is drained from your plumbing system. It is at this point that the technicians will advise you on the next steps you need to take, depending on the state of your plumbing system.