Hello everyone.

I have a model with socketweld flanges 1” (150# and 300#) and spiralwound gaskets. All flanges failed Peq check. Then I check them by method described in ASME VIII Div2 with next parameters:

- Flange material – A105N, studbolts material – A193 GR.B7
- Design pressure – 1650 kPa,
- Axial force – 9 N,
- Moment – 1 Nm,
- Gasket seating stress – 50 000 kPa.

Flange failed in seating conditions (radial flange and maximum average). After I change design pressure to 500 kPa, axial force to 0 N and moment to 0 Nm. Gasket seating stress is same – 50 000 kPa. Radial flange and maximum average in seating conditions not changed. So, I understand that specified parameters (in seating conditions) does not depend from forces and moments. How can I solve this problem? Could we manually change allowable stress in seating conditions up for 150%?