Inspection method · PRES
Pressure and leak testing
Strength and tightness tests are among the most important acceptance tests for pressure equipment, valves and hydraulic components.
01How it works
Hydrostatic tests fill the component with water (or another liquid) and raise pressure to a test value defined by the code, typically above design pressure, held for a defined time while the component is inspected for leaks and deformation. Pneumatic tests use gas and require additional safety precautions because of stored energy.
Leak tests detect and quantify leakage: bubble tests, pressure decay, vacuum, tracer gas and helium mass spectrometer methods, in order of increasing sensitivity. Valve tests include shell, seat and backseat tests with allowable leakage rates.
02Typical industrial applications
- Pressure vessels and piping
- Valves and pumps
- Heat exchangers
- Hydraulic cylinders and manifolds
- Castings requiring pressure tightness
- Tanks and containers
03Benefits and what it detects
- Proves strength and tightness
- Required by pressure equipment codes
- Detects through-wall defects and leaking joints
- Clear pass or fail
04Limitations
- Hydrotest water quality and drying matter for stainless and carbon steel
- Pneumatic tests carry high risk
- Test pressure must not exceed design limits
- Small leaks need sensitive methods
05Specifying and reviewing the method
Specify test medium, pressure, hold time, temperature, gauge range and calibration, and acceptance. Gauge range is usually chosen so that the test pressure falls in the middle of the scale.
Other references: EN 13445-5, ASME VIII, ISO 5208, EN 12266-1, API 598, ISO 20484 (leak testing vocabulary)