Regarding the flange standards HG20592 and HG20613, the issue of pressure application for flanges.
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In the flange specification HG20592-2009 (PN series), the maximum pressure rating specified is PN160, whereas in HG20613-2009 (CLASS series) the maximum pressure rating is PN420. Does this mean that when the system pressure exceeds 16 MPa, flanges from HG20592 can no longer be used, and instead those from HG20613 must be chosen? I would like to ask if this understanding is correct
It’s not wrong to understand it this way when making a choice. But in essence, it is a difference in standard systems: the former is the European system, while the latter is the American system. Generally speaking, it is best to use the same system for the same project, and avoid mixing different systems as much as possible.
According to standard definitions, this understanding is incorrect; flanges from two different systems cannot be compared with one another as they are not comparable. However, when pressure is used for comparison, that’s different. In fact, when pressure is truly compared, there is a difference between the PN system used in the Americas and the PN system used in Europe. The correct pressure rating in the American system is expressed in terms of Class pounds, while the PN value used in China is a relative figure that serves only as a reference – it isn’t as accurate as the PN value used in Europe
Another point is that the flanges specified in HG/T20615-2009 belong to the American system; in other words, all the piping used meets American standard outer diameters. Meanwhile, HG/T20592-2009 includes both American-standard and Chinese-standard pipes, and there is a difference between these two. If the pressure level is not sufficient, it is recommended to switch to the new JB/T82-2015 standard, where the maximum pressure rating for flanges is PN200. If this still isn’t enough, then refer to the GB/T9115-2010 standard, whose pressure ratings are PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, PN160, PN250, PN320, PN400, with the highest pressure rating reaching PN400
Referring to the records upstairs, I’m not quite sure; I think it’s the manual related to Ke Yicha