Compatibility between American standard flanges and Chinese standard flanges?
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For example, can PN20 DN25 be used in conjunction with 1 inch and 150 pounds? There are also American standards versus American standards, as well as Chinese standards versus Chinese standards. Please provide a summary; experts are welcome
National standard flanges come in American standard series and European standard series.
They should be able to be used together. . . The difference in size is just a matter of decimal places. .
PN20 DN25 should be the same as 1 inch CL150
The current major flange standards in China are all \"derived\" from established foreign standard systems, and they are mainly divided into European and American standard series. Those with grades such as PN16, 25, 40, 63, etc. belong to the European standard series ； PN20, 50, 110, and so on belong to the American standard series, corresponding respectively to ANSI 150, 300, and 600 pressure classes. In terms of size alone, PN20 DN25 flanges can be connected to American standard 1-inch 150BL class flanges; of course, the sealing surfaces also need to match. If you’re not sure, checking the dimensions in the standards will clarify things. In fact, it is best for paired flanges to be of the same standard; even if their dimensions are identical, the relevant technical requirements, materials, testing procedures, and requirements for accompanying accessories can vary. It is preferable to standardize them and ensure they meet the requirements of upstream clients. Especially for export projects, many foreign countries may not recognize domestic standards, and this must be clarified before making design selections.
CL150 can basically be used in conjunction with PN20, as both belong to the American standard system and are based on ASME B16.5. Domestic flange standards include HG/T20615, SH/T3406, GBT 9115-2010, etc. The flange fittings are all in order, but there is one small issue with the bolt holes: the national standard uses metric units while the American standard uses imperial units, so they aren’t exactly the same. On site, it has happened that the bolts were too thick and didn’t fit properly; therefore, when choosing gaskets, it’s best to use those that conform to the national standard, rather than those specified by ASME B16.20
HG20592 specifies which standards it can be used with. Take a close look and you’ll know.
There are two series of national standard flanges: Series I and Series II (or Series AB), which correspond to the American system and the European system respectively. Series I is roughly equivalent to the American standard, but there are a few specifications that differ, so care is needed.