How should flanges of different pressure ratings be connected?
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How should flanges of different pressure ratings be connected?
How could such a problem occur? There are also those with a small diameter that can be connected directly.
Theoretically, small-diameter pipes can be connected, but reputable design firms generally do not design them in this way. I once encountered a messy setup in which an 8-hole flange and a 4-hole flange were connected; and out of the 8 holes on the 8-hole flange, 4 holes did not have screws inserted into them~
But in some projects, the pipes are rated PN1.0, while the flanges provided with the equipment are rated PN1.6. Due to this difference in pressure ratings, the flange holes do not match; so how should they be connected?
Higher-grade flanges are allowed on lower-grade pipelines. Generally, unless otherwise specified, the material should be from the low-grade material pool, with flanges of two grades higher.
It is best to replace the flanges so that the specifications of the connections are the same.
In such cases, we generally do not allow direct connection, unless, according to the standards, the bolt hole sizes and seal surface dimensions for PN10 and PN16 are identical; in that case, it is barely acceptable. In other cases, a matching flange of the same grade must be provided separately for the equipment’s outlet flange; even if such a flange is not available during construction, it is advisable to purchase one promptly, as standard flanges can be acquired quickly.
The key pipes and fittings are all lined with plastic
That would be a bit troublesome; it would require customization... Forcing a connection can easily lead to leaks.
Replace the flanges with a higher pressure rating ones and connect them
Just replace the flange on the pipeline with one that is the same as the flange on the equipment base, and weld it again