What is the significance of pressure testing?
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The flange arrived with a label indicating PN2.0 (according to petrochemical standards), but the design requirements specify 2.5 Mpa. Therefore, he suggested conducting a pressure test at 3.75 Mpa; if it passes, would that prove that the flange meets the 2.5 Mpa requirement?
No, the flange sizes for PN25 and PN20 are different; passing the pressure test does not mean that the products can be used interchangeably
PN20 is for the American standard, while 25 is for the European standard
Obviously it’s not possible; the technical requirements are different. Whether a pressure test is successful or not doesn’t tell us anything.
It’s not possible; the PN value doesn’t only indicate a different pressure level, but it also reflects different flange sizes
No, one is a short-term load and the other is a long-term load.
It’s a bit confusing, so let me explain. PN2.0 is generally considered to correspond to 2.0 MPA, but this pressure value isn’t listed in the PN pressure classification system. It comes from American standards and is equivalent to 150 LB. The connection dimensions for these two standards are definitely different – things like flange thickness, outer diameter, and the number of holes, as well as their diameter, vary. A 150 LB flange can withstand a test pressure of 3.8 MPA, so it should be suitable for use, but it cannot replace a flange rated for 2.5 MPA
When materials are under overload for a long time, reaching their fatigue limit increases the likelihood of problems occurring.
No, experiments do not mean that substitution is allowed; selection must be made step by step in accordance with the specifications and material grades