Test pressure (gas system)
The test pressure ( PT: test pressure ) is the level of pressure when performing a strength test.
description
A pressure test is carried out on a pressurized component (pressure vessel, pipeline, steam boiler, pressure-retaining equipment such as valves, filters, etc.) in order to prove that there is sufficient strength reserve for the operating condition. The applied test pressure is therefore always above the maximum permissible operating pressure (PS). Due to the higher pressure, the materials are loaded almost to the yield point. (Note: When designing the components, appropriate safety factors are taken into account.) In addition, when determining the test pressure, the lower material loads at room temperature compared to the material loads at operating temperature are taken into account. For safety reasons, pressure tests using gases are usually carried out with lower test pressures. In these cases, however, additional non-destructive testing (z. B. required radiographic inspection , ultrasonic testing of welds ).
Information for the determination of the test pressure (PT) is normally contained in the applied technical regulations.
Examples
Examples of information in regulations for determining the test pressure:
- Pressure equipment directive : The higher value of PT 1 = 1.43 * PS and PT 2 = 1.25 * PS * K 20 ° C / K TS max is decisive. (Note: K 20 ° C / K TS max is the ratio of the strength parameters at room temperature to the value at maximum operating temperature).
- EN 13445 Unfired pressure vessels: see information on the Pressure Equipment Directive
- AD 2000 Merkblatt HP 30: see information on Pressure Equipment Directive
Applications
In the case of recurring tests (strength tests) on systems that require monitoring within the framework of the Industrial Safety Ordinance , the level of the test pressure is determined according to the applicable technical rules such as the Technical Rules for Operational Safety (TRBS).
It can also be the case that only leak tests are carried out on parts of the system in order to prove sufficient leak tightness of detachable connections. These are not strength tests and can therefore be carried out with test pressures below the permissible operating pressure.