Questions about HG/T20592-2009 chemical flanges?
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The same question: PN40 and PN25 have the same dimensions. If both are made of Q235B material, i.e., grade 1C4, then at 200 degrees Celsius, PN25 cannot be used at 2.0 MPa, and PN40 also cannot be used at 2.0 MPa at that temperature. With the same material and the same dimensions but different pressure ratings, what ensures this? !
At 200 degrees, PN25 cannot be used at 2.0 MPa, and at 200 degrees, PN40 cannot be used at 2.0 MPa. Where is it specified in the standards? I couldn’t find it.
At 200 degrees, PN25 cannot be used at 2.0 MPa, while PN40 can be used at 2.0 MPa at 200 degrees
This post was last edited by Baoji Chaosheng Titanium Industry on 2018-7-24 at 11:07. According to HG/T20592-2009, page 28: for pressure-rated temperature values, the maximum rated pressure at 200 degrees is 19.7 bar = 1.97 Mpa for PN25 1C4; it is 31.6 bar = 3.16 Mpa for PN40 1C4. As for the claim that the flange sizes are the same, it can only be said that they are identical in some cases – for PN25 and PN40, the sizes are the same up to DN150. DN200 and above (including DN200) are different. Study the standards carefully. Page 23, clause 7.0.5: If the two flanges on a flanged joint have different rated pressure values, the maximum allowable operating pressure for that joint shall be the lower of the two values, and the bolt torque during installation must be controlled to prevent over-tightening.
Thank you for the reply! My question is: for flanges of the same size and made from the same material, such as DN125, PN25 and PN40, is it acceptable to use Q235B as the material? At 200 degrees Celsius, the applicable pressure for PN25 1C4 is 19.7 bar = 1.97 Mpa, while the maximum rated pressure at 200 degrees Celsius for PN40 1C4 is 31.6 bar = 3.16 Mpa. Isn’t this contradictory?
Check the specific standards! ! ! ! ! ! ! ! ! ! ! !
The PN63 and PN100 flanges with DN10~DN40 sizes are the same in dimensions, and there are also aspects that may be difficult for you to understand. I’m sorry about your question; I don’t know how to answer it either. Since the standard has been established in this way, there must be a reason for it. I hope some expert can provide guidance.
It must be done to simplify the dimensions; within a small range, 2.5 is equivalent to 4.0, and 1.0 is equivalent to 1.6
It’s like pipes with dimensions of 25×3 or 20×3; the wall thickness takes into account not only the pressure-bearing capacity but also the pipe’s own strength (so that it doesn’t deform easily when suspended).