How to select the pressure rating for flanges
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The working pressure is 2.5 MPa, the pipe diameter is DN40 – what MPa rating should the flange have? ?
The nominal pressure of the flange should be selected based on the design pressure of the equipment or pipeline; it should generally be no less than the design pressure
That requires parameters such as the flange material and the design temperature of the equipment (pipes). If there are no special requirements regarding material and temperature, it is recommended to: 1. Choose a product with a nominal pressure of PN40 (HG/T20592-2009 PN series), or 2. choose one with a nominal pressure of Class300 (HG/T20615-2009 Class series). Either option is acceptable; the key factor is to determine what standard or series the flange being used in conjunction is based on.
It is a grade equal to or greater than the test pressure; the operating pressure is 2.5 MPa, and the test pressure is 2.5 × 1.25 = 3.125. Choosing PN40 is perfectly fine, as no further verification is required. It is also possible to select based on pressure by finding the maximum pressure that a 2.5 MPa flange can withstand; any value higher than that will work. But it still needs to be verified.
There is work pressure, as well as working temperature and material quality – all of these need to be taken into consideration. Higher temperatures require an increased pressure rating; different materials have varying heat resistance, which in turn determines the required pressure rating as well
Work pressure, working temperature, and flange material – higher temperatures require a higher pressure rating; different materials have varying heat resistance, which in turn determines the required pressure rating as well