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ASME B16.5 Flange Design vs Bolt Tension

ASME B16.5 Flange Design vs Bolt Tension

ASME B16.5 Flange Design vs Bolt Tension

(OP)
I'm trying to analyze my design that integrates flanges designed to ASME B16.5 dimensions on the inlet and outlet. I've been through the posts on bolts here and there is a lot to take in, but i assumed that asme would have a code with tables listed somewhere. The flanges in b16.5 all have specified dimensions based class size and pressure rating based on flange material at that class size. All the talk in these boards about bolt tension and gasket face pressure are nice if you are trying to set your bolt tension for a specific application but really say nothing about flange itself.

Is there a table somewhere that says for flange of WCB material in class 600 size use 2000 lbs of bolt tension per bolt. Because i'm driving myself silly with all the what ifs but the flanges had to have been designed with a specific number in mind. Why not publish that number? and if they did publish it, what spec did they publish it in? b16.5, b16.34 PCC-1, BPVC VIII 1 or 2, B31.1, B31.3, or some other code dealing with bolts only, or a code dealing with gaskets, i'm a little lost here.

On a side note i get ASME has to charge money to support all the R&D that goes into making these codes, but you literally need 15 books to design a valve to make sure you are meeting code and no one tells you which ones you need. You could start with B16.34 but then it references 2 or 3 other books with themselves reference 2 or 3 other books and so you buy and buy and buy and oop theres been a new version released, looks like you have to buy again. Sorry thats my soap box, they are doing great work but damn.

RE: ASME B16.5 Flange Design vs Bolt Tension

The B16.5 geometries were not sized with the current assembly bolt loads in mind. This thread has some background information https://www.eng-tips.com/viewthread.cfm?qid=454965 ASME PCC-1 Appendix O provides bolt loads that represent the flange limit, which is what I think you are after. If your custom design is bolting up to a standard flange, and you happen to be using assembly loading in your design, then this would be a good place to start. If you are using code formulas to size a flange, then this is not currently based on assembly loads.

RE: ASME B16.5 Flange Design vs Bolt Tension

(OP)
I'll check PCC-1 thank you.

By "using code formulas to size a flange" do you mean to pick the flange size or do you mean design of the flange. Are code formulas more conservative so if you check current flanges to code formula loads it'll show them as under designed (i.e. too weak).

RE: ASME B16.5 Flange Design vs Bolt Tension

By code formulas I mean design calculations such as VIII-1 Appendix 2. Correct, a lot of the standard B16.5 flanges do not pass design calculations. However, they are acceptable for pressure and temperature based on their rating (B16.5), external loads based on the conservative moment factors (VIII-1 / VIII-2) and assembly bolt loads based on PCC-1 Appendix O.

RE: ASME B16.5 Flange Design vs Bolt Tension

(OP)
Thank you again for the insight.

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