Regarding ball valve pressure testing and overall unit pressure testing
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After the ball valve is assembled, a pressure test of the product is carried out. Once this test is successful, an overall pressure test of the entire unit is performed as well. I would like to ask whether this final overall pressure test is necessary Is it below a certain size that it can be omitted, or must it be done for all sizes?
The pressure testing procedures for valves are as follows: 1) Hull strength test, with a testing pressure of 1.5 times the nominal pressure; 2) Sealing hydrostatic test, with a testing pressure of 1.1 times the nominal pressure; 3) Air sealing test, with a testing pressure of 0.6 MPa. All valves must undergo these three tests before leaving the factory, regardless of their diameter. I’m not sure if you’ll understand if I put it this way.
I see, but after completing the above tests, the same process will be carried out again after the product is painted; this is called a full-unit pressure test. My question is: does this full-unit pressure test need to be done for all sizes of diameters?
Generally, valves are not subjected to pressure testing again after being painted, unless they are installed in pipelines as part of the overall pipeline pressure testing.
There is another re-inspection to be carried out before installation upon arrival at the site