Flange connections of different pressure grades (with varying numbers of bolt holes)
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The flanges are selected in accordance with the JB/T81-94 standard. The available flanges are of PN1.0 and PN1.6 types, both with a DN80 size; the bolt hole spacing is the same, allowing them to be connected. However, the PN1.0 flanges have 4 bolt holes while the PN1.6 flanges have 8 bolt holes, and on-site inspection rejected this arrangement. Is it feasible to connect in this way (with inconsistent numbers of bolt holes)? Are there similar standards available? Thank you!
I’ve never seen different pressure levels connected together like this. Go and check the pipeline construction specifications.
When fittings at 1.0MPa and 1.6MPa are used together, they can only be operated according to the lower standard. In other words, the operating pressure for your pipeline design is 1.0 MPa. If you have designed a pipeline of 1.0 MPa, there’s no reason not to approve it. I can only say he is nitpicking. But if the design requirement is 1.6 Mpa, it makes sense not to conduct acceptance testing. (In actual applications, when strict requirements are not in place, piping components (flanges, valves) at 1.0 MPa can be interchanged.) ）
There are standards in place; different grades of flange connections have specific requirements. They can be used together in pairs, but it must be done in accordance with the standard requirements
GB-50235-2010 Code for Construction of Industrial Metal Piping Projects, Section 7.3 specifies the requirements for flanges
Flanges of different pressure ratings cannot be used interchangeably; this is the same result regardless of which standard you consult. Replace it with the same flange; it’s highly unlikely that the on-site supervisor will approve such a connection. . .
Please don’t mislead people; stop using those tricks to deceive the client when things get a bit confusing on site. Flanges of different grades must never be used interchangeably.
Um, I was just wondering, is this a mandatory requirement? I really don’t know