Seeking advice on flange selection
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Hello, fellow sailors! I have a question: Are there any regulations specifying a minimum pressure rating requirement for the flanges on pipelines carrying flammable and toxic gases (with high toxicity)? (I have seen that the current regulations require a minimum pressure of PN20 for Class A1 fluids, while no such requirement exists for Class A2 fluids. The toxic and flammable gases used in our company are highly hazardous; the operating pressure is 0.13 MPa. Can flanges with PN10 rating be used?) I’ve heard from some designers that for flange seals involving flammable and toxic gases, a flat surface cannot be used; at least an RF surface or a better sealing design is required. But in SH3059, I only found the regulations regarding the inability to use plate-type butt weld flanges; I didn’t find any regulations concerning the requirements for the sealing surfaces. I was wondering whether what the designer said is correct, or if I just haven’t found the relevant specifications Thank you!
Is HG20592 not used in the chemical industry for RF surfaces?
There is a detailed explanation on the selection of flanges in the section on flanges in hg20583.
It seems the teacher above didn’t explain my question; I hope fellow netizens can help answer it. HG20583 refers to the vessel flange
Refer to Sections 7.2.4 and 7.2.3 of HG/T20583-2011.
That’s a good question. I’ve been using 20592 and 20615 for a long time; I really didn’t pay attention to the scope of application for the FF surface. I just checked the fifth edition of the Chemical Process Design Manual, and there was no information regarding the selection of FF surfaces there: L
PL FF PN10 is suitable for DN10~600, but the maximum pressure rating for PL FF is PN16. In cases where the substances are highly toxic or extremely toxic, a higher grade is chosen for design purposes; therefore, FF is generally not used
When it’s safe, consider the cost!
Firstly, an operating pressure of 0.13 MPa is not high; choosing a higher pressure level is simply more secure. As for the sealing surface, an RF surface will suffice, while for flange types, WN is appropriate.
This post was last edited by *nht1 on 2020-5-12 09:38: WN, RF, or FM/M – at least PN25 is required