PCC-1 Table 0-4.1 Bolt Stress Limit for Series A really low

[iangineer]

Hi all,

PCC-1 Table O-4.1-2 Bolt Stress Limit for Series A flanges looks really low. All of them range from 28ksi to 37ksi. That seems really low compared to what I calculate they can handle.

For example:
36" 150# Series A flange is 2" thick.

I calculate that the maximum bolt load for the (44) 7/8" diameter bolts is about 167ksi (theoretical max since I know the bolts can't be stressed that high).

In the PCC-1 table, a 36" 150# flange has a bolt stress limit of 37ksi determined using Elastic-Plastic FEA.

Please let me know why it's so low.

Thank you

 

[BJI]

How have you calculated the maximum bolt load and what is your assessment criteria? If you calculate flange rotation at this bolt load, how does it compare to the flange rotation in Table O-4.1-3? Assembly rotation would typically be limited to around 1 degree (O-4.1(a)), so the E-P analysis has shown that the GPD point for the flange is reached prior to this nominal rotation limit.