Flange rigidity and note G5

[jordiloureiro]

According to ASME II part D, note G5 is not recommended for bolted connections due to higher deformation at gasket seating. ASME VIII appendix 2-14 provides a method of checking flange rigidity, so the question is: Can I use material within note G5 if I check its rigidity according to ASME VIII app. 2-14? This method using note G5 material will provide the same results as using the same material but not wit G5 note?
Thanks

 

[SnTMan]

jordiloureiro, IMO, note G5 is concerned more with general service that just "gasket seating", but I don't think use of the lower allowables is MANDATORY.

Can I use material within note G5 if I check its rigidity according to ASME VIII app. 2-14?

Probably yes, but I wouldn't.

This method using note G5 material will provide the same results as using the same material but not wit G5 note?

I doubt anyone can say for sure, depending on what you mean by "results". Use of the higher allowables will give the thinner flange, which may or may not meet rigidity. Rigidity is a function of modulus of elasticity rather than allowable stress, modulus is the same whether the allowables are the G5 values or otherwise.

The exact details of the flange will have a great deal do with the design conditions and I would not feel at all confident in stating any general rules. Regardless of whether a given flange design meets the Code, it HAS to perform well in service for a long time.

Experience has shown me that a flange is not the place to economize overmuch on a design.

Regards,

Mike