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Allowable joint fastener pre-loads

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CodyByron

Mechanical
Mar 29, 2013
2
I'm sure this has been talked about before, but I am not finding exactly what I am looking for.

To be specific, I am looking to use M8 12.9 (S ult 174ksi) fasteners for a flanged joint for a pressure vessel. What is the maximum allowed tensile pre-stress allowed in the fasteners?

Thank You
 
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CodyByron, see this: thread794-338565

Check with your gasekt supplier, see what they recommend for an applied seating stress, work from that.

Regards,

Mike
 
I really appreciate your response and links. I think what I am getting at is the BPVC pretty much wants a F.O.S. of 5 when it comes to fasteners. (if I am wrong please point me in the correct direction) Does that go for preload as well? Or are those two things treated differently? How do you bring a fastener to well beyond yield and not have stress in the fastener 1/5 of the ultimate tensile?

Thanks
 
You're mixing up design and actual usage. The design margin of 5 against ultimate is for the design of the flange.

Refer to ASME PCC-1. You'll find what you seek there.
 
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