I have a question regarding flange standards
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GB-T 9119-2000 \"Flanges for welded steel pipes with flat face and protruding faces\" specifies 8 bolt holes for flanges of DN80, PN1MPa, whereas the \"Flange standards for the machinery industry JB_T81-94\" specify 4 bolt holes for such flanges; there is a discrepancy – which standard should be followed? Also, could there be any issues with the flange connections for 8-hole and 4-hole versions? PN1.0MPa Thank you!
Why don’t the two flanges used by the poster need to follow the same standard? Using four holes for connection is definitely fine, but it is still recommended to use flanges of the same standard.
This question is actually yours, the original poster – when doing design, one must follow the same standards
Four-hole and eight-hole can’t be connected at all. . .
I don’t know how to put it. This wasn’t a problem to begin with
As long as the same standard is specified, there shouldn’t be any issue with 4-hole and 8-hole connections, right? :)
An 8-hole flange pairs well with a 4-hole flange as long as the center distance between the bolt holes is the same; just pay attention to the position of the holes when welding the flanges to the pipes, and there will be no problems. I’ve encountered this issue before – the drawings provided for ordering matching flanges were based on the new standard with 8 holes, but the flanges delivered by the manufacturer had 4 holes according to the old standard, so it’s impossible to be picky about that
It should be correct, as long as the eye spacing is the same. But it seems that no one buys one with flanges, one with 4 eyes, and one with 8 eyes
It’s because the standards you’re using are not unified. You should standardize the flange standards; the current standards set by the Ministry of Machinery have been rendered obsolete, and it is recommended to use the standards set by the Ministry of Chemical Industry.