Who can provide a detailed explanation of the upper seal test for valves? ?

The upper sealing test is to seal the valve’s packing, right? I don’t know much.

Upper seal test of the valve? What type of valve? The simplest sealing test – pressure testing. For example, for a gate valve with a nominal pressure of 1.0, after raising the pressure to the test pressure, soap water is sprayed on the valve to check for bubbles on the valve cover, packing, and valve body.

http://www.zc-valve.com/news/detail/3.html The information available here is also good: it explains the basic terms related to pressure testing, the upper seal test, and the tests used to evaluate the sealing performance of the seal pairs between the valve stem and the valve cover. *******************......

Pressure testing for general purpose valves Standard: GB/T 13927 1. Terms (1) Valve test pressure: The gauge pressure that should be applied inside the valve cavity during testing； (2) Shell test: A pressure test conducted on the entire valve housing, which is formed by combining the valve body, valve cover, and other components. The purpose is to test the tightness of the valve body and valve cover, as well as the pressure resistance of the entire housing, including the joint between the valve body and valve cover. (3) Sealing test: A test to evaluate the sealing performance of the moving parts and the sealing surfaces of the valve body. (4) Upper seal test: A test to evaluate the sealing performance of the seal between the valve stem and the valve cover. (5) Test duration: The length of time the test is conducted at the specified pressure. Upper seal test (this test should be performed on valves equipped with an upper seal mechanism). The inlet and outlet of the valve are closed, and the packing gland is loosened (unless the valve has a device for checking the upper seal, and it is possible to reliably assess the performance of the upper seal without loosening the packing gland); the valve is then in its fully open position. The upper seal is closed, the internal chamber is filled with the test medium, and the pressure is gradually increased to the specified test pressure, after which the sealing performance of the upper seal is checked.