I am reviewing a design for a flange designed in accordance with appendix II of ASME Sec.VIII, Div.1. I have inputted all data given by the designer of the flange into the CodeCalc software. It appears that CodeCalc inputs an additional bolt correction factor when calculating the "moments for internal pressure". Why do you do this as it is not supported anywhere in appendix II of the ASME code? This is somewhat embarrassing as I cannot find anything to support this additional factor within the code. It appears that this bolt correction factor is directly related to the "m" and "Y" gasket factors. The designer has an "m" factor of 6.4. As soon as I input this factor it immediately fails. The "Y" factor is 2900psig.

Thank you.

Dear Duane,

The bolt correction factor is to account for bending of the flange in between the bolts. If the bolts are too far apart, then the flange face in between the bolts (in circumferential direction) can open up and cause leakage.

This is per RCB-11.2 in the TEMA standard. In the program if the circumferential bolt spacing is more than that suggested in the TEMA std., then the flange moments are multiplied by this factor. Thereby, increasing the flange thickness and as a result making it stiffer.