Help with flange selection

[dan240]

Hello,

I have a small design task for an R&D project and I'm trying to find an off-the-shelf solution for some flanges. We are building a small pressure vessel with a roughly 2.5" ID. It will operate between ATM and 150 psig, ambient temperature......should be easy.

There are several spool sections that need to bolt together and they need to be concentric and located axially (length wise) to within a reasonable tolerance. Right now we have flat pipe flanges with flat viton gaskets in the assembly design. The clearance holes on the flanges won't provide the concentricity we need and the flat gaskets don't seem like they will control the axial length very well.

If this was a vacuum assembly I would use an ISO flange. They have a centering rings that locates the flanges so they are concentric and bottom out so length is controlled fairly well.

Is there something analogous to this that will handle the 150 psi pressure?

.....I could add shoulder bolts and/or machine an annulus for a centering ring on our existing flanges. I thought maybe there is something out there already I might be able to use that is OTS.

Best,
Dan

 

[zdas04]

If I had requirements like yours, I'd stay away from ring-joint flanges (too sloppy by design) and drill 3 alignment holes in each Raised Face Weld Neck ANSI 150 flange (my book says they come in a 2-1/2 inch nominal pipe size, but I've never had occasion to look for that size). I'd use spiral wound (flexitalic) gaskets because when the winding crushes, the backing ring becomes a spacer that gives you very precise spacing between flange faces. If you need better than that you're going to have to fab it all yourself in a machine shop.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[donf]

Here are several off-the-shelf (OTS) options:

1. High pressure hubs (aka Grayloc) Although typically used for high pressure applications, they are inherently self aligning, smooth transition connectors. A disadvantage is that the connectors have to be spread apart to install/remove seal ring.

2. Sanitary fittings (aka Tri-clover) - Again somewhat self aligning. Usually found in tube sizes, but pipe sizes are available.

3. Felker Brothers and Young Industries offer self aligning male-female O-ring type flanges.

4. If you do elect to use conventional B16.5 flanges, consider using full face, special ID gaskets. The full face allows visual alignment with flange OD. Size the ID to match pipe bore. And full face sp/wd gaskets are available.

Let us know how it works out.

Best regards,

donf

 

[LittleInch]

I would have a look at NORSOK compact flanges - search Norsok L-005. These mate up face to face so eliminate the issue with gasket compression and are very rigid. They do #150 flanges of this size.

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Also: There's usually a good reason why everyone does it that way