Doubts about valve sealing tests
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Refer to Article 5.3.2 of SH3518-2013 \"Specifications for Inspection and Management of Petrochemical Valves\": \"...Gas shall be used as the medium for low-pressure sealing pressure testing.\" In the terminology notes, “should” indicates strictness – it is necessary to do so under normal circumstances. I would like to ask an expert to explain the reason for using gas. Thank you! ! !
Sealing tests use gas, which allows for more accurate monitoring of the sealing quality
Please note the difference between strength tests and sealing tests; their purposes are different. For applications involving hazardous or flammable materials, a sealing test is necessary, and this is usually required for gases.
Gases have a stronger permeability than liquids!
Liquids are used for sealing in low-pressure applications, and they do not exhibit strong capillary penetration in the sealed surfaces. Gases can be used to enhance the inspection. For products with high requirements, high-pressure gas sealing tests are also used, but safety precautions must be taken, such as the use of pits and cameras for monitoring.