Maximum gap between flanges before bolt up
Maximum gap between flanges before bolt up
(OP)
Where would I find the maximum allowable distance between piping flanges prior to bolt up? This is assuming no spacer will be installed between the flanges. I know this is a matter of piping fit-up, but I need to know in what code and where I can find the maximum allowable distance. I first thought B16.5 then B31.3, but I can’t seem to locate the answer. This is in boundary petro refinery piping.





RE: Maximum gap between flanges before bolt up
RE: Maximum gap between flanges before bolt up
RE: Maximum gap between flanges before bolt up
RE: Maximum gap between flanges before bolt up
RE: Maximum gap between flanges before bolt up
Cheer,
TGS4
RE: Maximum gap between flanges before bolt up
With reference to the specified gap between flanges used when designing a piping system, if your pipe specs call for the spiral-wound gaskets used in most refinery services, this gap is 1/8". The gap used is normally the nominal gasket thickness and should be noted in the Piping Materail Specifications for the line in question.
The answer to what is the maximum allowed gap is not clear cut and requires good engineering judgement. A lot of factures come into play such as line size, system flexibility, operating temperature and equipment connections.
1. If you think you may not be able to seat the gasket, then the gap is to large.
2. If your line is connected to rotating or other sensitive equipment, closing an excessive gap might cause your equipment loading to exceed the allowable, not just on bolt up but also when the system is in operation.
A GOOD Field Piping Engineer should be able to resolve most of these issues as they come up during construction, if not, shoot it back to the Engineering Contractor for a quick answer.
Good luck,
NozzleTwister
Houston, Texas
RE: Maximum gap between flanges before bolt up
If you know what cold spring is, then don't read on. If you don't, then here's a quick description: If you have a piping system that gets hot, it makes sense to make the pipe a little short so that when it thermally grows, it grows to the right length and doesn't impose unnecessary forces on the rest of the system. That "shortness" is often set at flange faces.
Cheers
Rob