The hydrostatic testing consists of filling an equipment with a fluid (generally colored water) at a set test pressure, and for a given period of time, to check the existence of leakages. The applied test pressure shall exceed the working pressure by a variable factor. While the equipment is under pressure, the staff checks possible leakages: the test is passed if the equipment is able to bear the test pressure without leaking for the set time, it fails in case leakages are detected
Before starting a hydrostatic test, the staff in charge should pay attention to the testing fluid chemistry and how it may impact the equipment.
When a hydrostatic testing on a specific equipment is not possible or recommended, the pneumatic test is a suitable alternative.
HYDROSTATIC VS PNEUMATIC TEST
As noted above, a hydrostatic testing is executed by using chlorinated water or other fluid to check the existence of leakages in the equipment.
A pneumatic test uses compressed air or inert gases to test an equipment. Pneumatic tests are generally executed on low-pressure equipment or small parts or when a hydrostatic test cannot be executed for whatever reason.
A FAILED HYDROSTATIC TEST (VIDEO)
The video shows how a hydrostatic test is executed and a failure case: