Discussion on the role of voltage withstand testing
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Hydraulic testing and pneumatic testing are collectively referred to as pressure resistance testing. Pressure resistance testing involves using a testing medium at a pressure higher than the design pressure in order to examine the strength of the container. Its function is to inspect the overall manufacturing process of the container, the strength of various components, the strength of welding joints, and the sealing performance of all connection surfaces. It involves a comprehensive evaluation of aspects such as design, materials, and manufacturing, and is therefore an important measure to ensure the safety of the equipment. Its purpose is to directly assess the voltage resistance, to eliminate some mechanical stress, to correct the shape, and to alter the stress distribution; it also allows for the measurement of elongation, expansion, stress, etc., in order to verify the correctness of the design and manufacturing. From the perspective of fracture mechanics, in addition to the effects mentioned above, the pressure test also applies high stresses beyond normal operating levels at the tips of any existing defects, thereby creating residual compressive stresses in those areas. This makes it difficult for cracks to form during normal operation, thus serving as a pre-stressing mechanism to prevent brittle fracture. The narrative is incomplete; feel free to add more
The hydraulic test is fundamental and a prerequisite; only after a successful hydraulic test can the airtightness test be carried out. Of course, the main purpose of a hydraulic test is to ensure and verify strength, ensuring no deformation, abnormal noises, or leaks occur. Generally, if the hydraulic test is successful, the probability of the airtightness test being successful is high (the pressure used in the hydraulic test is higher than that used in the airtightness test). Additionally, water is commonly used as the medium for hydraulic testing, as it is inexpensive and available everywhere. In contrast, nitrogen or other gases are typically used for airtightness testing; they are more expensive and often have to be purchased externally. If airtightness testing is carried out without first performing a hydraulic test, any failure will require redoing the process, which increases costs and prolongs the testing time.
Purpose of the pressure test: 1. To examine the macroscopic quality and airtightness of the pressure vessel； 2. It finally checks the overall strength and reliability of the container, reduces the peak stresses in certain local areas, and blunts the crack tips; for pressure and vacuum containers, it also serves to verify their integrity ； It also serves to check the foundation settlement for large pressure vessels manufactured on-site ； Through short-term overpressure, it is possible to reduce the peak stress in certain local areas, thereby eliminating or decreasing stress to some extent and helping to make the stress distribution more uniform. Short-term overpressure can induce a closing effect on cracks, blunting their tips and thereby enhancing the safety of the container when operating under normal working pressures. Since gases of the same volume and pressure release much more energy upon explosion than liquids, liquids are used as the testing medium in order to reduce the risks associated with the rupture of pressure vessels during pressure testing. Since water is readily available for use and possesses all the properties required for pressure testing, it is commonly used as the medium for such tests; hence, pressure testing is also known as hydrostatic testing. This post was last edited by Xuehua on 2009-4-10 10:15.]