Issue of the duration for maintaining the valve strength test pressure
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The holding time for the strength test pressure of general valves ranges from a few seconds to 300 seconds, while during pipeline strength testing, the pressure is maintained at 1.5 times the operating pressure for 10 minutes. When valves and pipelines are tested together, will the valves leak? What if it’s only the case for cold water pipes?
There are standard requirements for the pressure testing time; as long as it meets the standards, it is acceptable
This pressure test is primarily used to assess the strength of the valve. The testing carried out in the factory takes less time than the hydrostatic testing done on-site; basically, if it works fine in the factory, it will work fine on-site as well
The valve is installed along with the pipeline, and the design pressure of the pipeline is certainly lower than the nominal pressure of the valve. If the valve passes its strength testing, there should be no problems during the pipeline pressure testing
Piping pressure testing generally does not involve valves. If it has a valve, it should also be in the open position, right?
Generally, tests are carried out based on the pipeline pressure; this is exactly what we do during the commissioning tests of our equipment
Thank you to all the experts above for their enthusiastic answers. There are two more issues that need to be confirmed: 1. The strength testing time for the valves is quite short; after installation, during the pressure testing of the pipeline at 1.5 times the operating pressure, the testing duration can be 10 minutes or 30 minutes (for fire protection systems), or even longer—anything that isn’t excessively long will do. It’s best to have reliable evidence for this. 2. The system operating pressure is 0.96 MPa, and the test pressure is 1.44 MPa. Should the valve be selected for a pressure of 1.0 MPa or 1.6 MPa?
If the nominal pressure of the valve is higher than the pressure used in the pipeline strength test, it is no problem to test the valve together with the pipeline； If the nominal pressure of the valve is slightly higher than the operating pressure of the pipeline, when testing the valve along with the pipeline, it must remain leak-free at 1.5 times that pressure for 30 minutes; otherwise, the valve must be removed or a valve with a higher pressure rating must be used.
How long can the valve remain problem-free during on-site pressure testing? 30 minutes or longer? Why is the pressure testing time in some factories only a few seconds?
According to GB/T20801, the on-site pressure testing is required to last for more than 10 minutes. The standards for pressure testing in factories are different from those used on-site, and the criteria behind their establishment also differ. The conditions on-site as well as the testing methods vary, which is why the standards set are different as well. In factories, the focus is mainly on testing strength, and the testing equipment there is more specialized, making it easier to detect any issues; therefore, the testing can be completed in a shorter time