In terms of a gas storage container, (also known as a gas storage cylinder or pressure vessel), a hydrostatic pressure test is a test of the structural integrity of the container every ten years from the date in which the cylinder was manufactured or the first fill date.
The phrase "hydrostatic pressure test" finds its root in the greek word hydro meaning water or in this case static water under pressure. In simplistic terms the process involves the following;
- remove the gas storage container from service;
- remove the gas from the container (this may include storing the gas for later reuse);
- inspect the container internally and externally for any condition that might adversely affect its function;
- fill the container with water;
- test the container under pressure (typically 1.5 times normal operating pressure);
- inspect the container for any leaks or conditions that might adversely affect its function.
- replace disposable components such as gaskets, seals and the like;
- reinstate the gas storage container by refilling.
Hydrostatic pressure testing is considered a non-destructive test however the purpose of the test is to identify any weakness in the structural integrity of the container. For this reason, a gas storage container tested under pressure may fail and then must be replaced.
The hydrostatic pressure test should be conducted in accordance with Australian Standard AS AS 2030.1 which specifies requirements for the verification, filling, handling, inspection, testing, and maintenance of refillable gas cylinders for the storage and transport of compressed gases, where the cylinders exceed 0.1 kg but do not exceed 3000 kg water capacity, other than acetylene cylinders, non-refillable cylinders and vacuum-insulated cylinders.