ASME PCC-1 Appendix O Leaving You Stressed?
ASME PCC-1 Appendix O has a lot of stress values to look up (or calculate) and using “defaults” isn’t going to help you solve real world problems. Over the next few weeks I’ll be going over where to get some of the stress values you will need in order to properly determine bolt torque values using ASME PCC-1 Appendix O.
Maximum Permissible Bolt Stress, Sbmax
Minimum Permissible Bolt Stress, Sbmin
Target Assembly Gasket Stress, SgT
Maximum Permissible Gasket Stress, Sgmax
Minimum Operating Gasket Stress, Sgmin-O
Minimum Seating Gasket Stress, Sgmin-S
Assembly Bolt Stress, Sbsel
Wait, just seven stress values? That seems way too easy! It is! But let’s start here and save the Maximum Permissible Bolt Stress for the Flange, Sfmax determination calculation using WRC 538 for after your exam.
B16.5 Blind Flanges as Reducers
Ever see ASME B16.5 blind flanges as reducers?
Just throw any pipe in a standard ASME B16.5 blind and you’re good-to-go, right?
No. That “standard” ASME B16.5 blind flange may not be “standard” once you decide to start drilling holes in it. Many times ASME B16.5 blind flanges used as reducers include pipes larger than allowed in B16.5 without a reinforcement calculation. Please make sure your facility has proper documentation for ASME B16.5 blind flanges used as reducers.
Use ASME PCC-1 Appendix O to Fix Leaky Gaskets
Do you have an issue with leaky gaskets?
A lot of people message me complaining about leaky flange gaskets and wondering what kind of gaskets I recommend to help. The fact of the matter is that gasket quality and performance has never been better. I have found that many times the real problem is that the gasket was not considered during the design phase. Gaskets are an important part of flange design. Treat them that way.
Have you performed ASME PCC-1 Appendix O for your flanges?
An approach in ASME PCC-1 Appendix O can help you make sure your gaskets are being seated correctly. The gasket needs to be below the maximum permissible gasket stress, above the minimum seating gasket stress, and above the minimum gasket operating stress. In this example the minimum gasket operating stress is not being maintained at the operating condition.
Make sure you perform ASME PCC-1 next time you open up a pair of flanges.