Is the valve pressure test a single-sided seal test or a double-sided one? . .
Thread Content
In valve testing, there are tests such as shell strength testing, upper seal testing, and seal testing – how many of these have everyone carried out? For example, in the case of gate valves, do you conduct strength tests on one side only or on both sides? Has anyone else done the upper sealing experiment? I’m also very helpless. . .
1. For valves equipped with an upper seal, the packing should be removed to conduct a sealing test. After the upper seal is closed, it should be checked for any leakage. When performing the packing sealing test, the upper seal must not be in its sealed position； II. For strength testing, the inlet and outlet valves should be closed, the packing gland should be tightened to maintain the test pressure, and the moving parts should be in a partially open position.
Theoretically, they all need to be done, but in practice, we often don’t carry out sealing tests; for such tests, we only check one side and ignore the other. . . :L
I’ve never understood the concept of upper sealing – could it be the sealing at the valve stem packing, as mentioned in Building 2? ? Should a sealing test be carried out with a pressure of 0.6 MPa, or should it be 0.6 times the nominal pressure?
Wedge gate valves do not require a double-seal test. According to API6D, when required by the customer, flat gate valves and line ball valves sometimes need to be manufactured
This isn’t a big deal at all. At the beginning of the year, we produced a batch of flat gate valves with capacities ranging from 28 to 600 LB. The customer required that the shell withstand a water pressure of 16.5 MPA for 30 minutes; they also wanted the shell to withstand an air pressure of 2 MPA for 30 minutes. The water pressure seal requirement was 11 MPA. We tested by applying pressure to the left side and checking the exhaust hole on the valve cover for 30 minutes, then did the same on the right side. When pressure was applied to both sides at 11 MPA, we checked the exhaust holes again after 30 minutes. The same method is applied for low-pressure gas sealing. 4 units were pressure-tested for 89 days. :lol
This post was last edited by hhk9801 on 2019-5-29 at 14:05. It is differentiated based on different types of valves and the various requirements of customers. As for the strength testing of the valve body, it goes without saying that this test must be carried out. The upper seal is indeed the location of the screw rod sealing packing, and it generally needs to be installed; however, some types of valves do not require an upper seal test. Finally, a sealing test must also be carried out. Whether it is a one-way seal or a two-way seal depends on the type of valve itself and the user’s requirements. Most valves have a one-way seal, meaning sealing in the direction of flow of the medium; however, there are also many valves with a two-way seal, in which case sealing tests need to be conducted in both directions.
Upper sealing refers to the presence of an upper seal, which is also known as reverse sealing. B16.34 specifies that the valve stem packing should be in a loose state when performing the upper seal inspection. Testing at the filler area is definitely necessary; a separate test will reveal external leakage. Regarding the two-way sealing issue of valves, the flow direction is generally not indicated; either side can be used. For those with specific flow direction requirements, testing should be carried out according to that direction.