Water pressure of 800# valve
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Hello everyone: Since my valves are socket-welded valves with a diameter of 2”, their pressure rating is 800#. The design pressure for this pipeline is only 1 MPa. However, the client requires that we conduct a hydraulic test on these valves at 800# pressure. Since the site does not have the capability to generate such high pressure, I believe that a pressure of 1.5 MPa would be sufficient. I would like to ask for your advice on how to explain this situation to the client – is it really necessary to carry out a hydraulic test at 800# pressure in order to meet the requirements?
Why is the pressure in the pipeline different from that at the valve? What is the design principle behind this? Could you explain it in more detail?
The pipeline pressure is 1 MPA, while the valve pressure is 800#. For the pipeline, a testing pressure of 1.5 MPA is sufficient; of course, the valve is required by its manufacturing standards to be able to withstand a pressure of 800#. You have chosen a too high pressure rating for the valve, but that’s not a problem. It is necessary for the pressure of the valve to be slightly higher than that of the pipeline; however, a significantly larger difference is merely a waste and has no impact. Therefore, when conducting this pipeline test (your main goal is to meet the pressure requirements for the pipeline), it is sufficient to carry out a pressure test at 1.5 MPA (this pressure is adequate for the pipeline). If you want to test the pressure rating of the valve itself, you can conduct a pressure test at 800.
This is common: for some pipes and valves with a diameter of 1\" or 2\", those with SW or NPT connections use valves made of 800# material, while those with flange connections use materials corresponding to pipe class 150 and similar standards
It depends on what the user requests. In actual use, you just need to conduct pressure testing according to the pressure rating of the pipeline, as that is sufficient for normal operation. But if the user insists that you follow the design specifications of the valve, then you have no choice but to comply!
If the client requests pressure testing of the valve, then simply remove the valve and take it to a suitable place to test for leaks, right? Just pressurize the pipeline as usual. One should try their best to meet the owner’s requirements.
The owner’s requirement is not a pressure test of the pipelines, but rather a pressure test of the valves themselves, which is specified in the valve acceptance requirements. If the manufacturer has pressure test records, the on-site pressure test can be waived. Therefore, the pressure test should be carried out in accordance with the CL800 rating of the valve itself; the owner’s requirement is not excessive.
Strength tests must be carried out in accordance with the relevant standards
How is a socket-welded valve subjected to a hydrostatic test? What tools to use?