Standard selection for large flanges
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European standards are to be used, with DN800 pipes. Previously, flanges of version 97 with necks and a PN25 rating were used; however, the current version 2009 specifies that flanges with necks and a PN25 rating have a maximum diameter of DN600. What should be done?
This post was last edited by COLORZERO on 2015-9-1 at 10:33. We can’t use NB/T47023-2012 after all; you’ll have to refer to HG20595-97 or HG/T20592-2009 for standard flanges and create your own custom design
The allowable stress of the flanges in version 97 at low temperatures is higher than that in version 2009; therefore, the thickness of the flanges in version 97 is smaller than that in version 2009. It is recommended that the manufacturer prepare non-standard drawings based on the dimensions of version 97, with the flange thickness being increased appropriately after calculation by the manufacturing plant.
In other words, 2009 is more conservative, right? So were the non-standard drawings provided by the manufacturer in the past problematic?
Yes, it is conservative, so I think it’s a bit problematic to produce non-standard drawings in exactly the same way as before. But you said that one is only PN10; presumably the pressure and temperature aren’t high, so it should be fine in actual use.