what it is saying is that B 16.5 doesn't in the end care what material you make the flange from, these are the highest pressure ratings for that class of flange.
So if you found some super duper material which was twice as strong as your current material, it doesn't mean you can double the flange pressure rating for that temperature.
If you want to go differently then design your flange to ASME VIII, but usually you find you need thicker flanges than ASEM B16.5.....
Does that make sense?
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First of all, i'm sorry for double posting i was not aware about the rules.
Secondly, i'm asking about the difference between pressure value mentioned for each group materials individually and the one mentioned in table A-1?
For example, i have an already installed class 600 flange with material A217 Gr.C12 considering that maximum pressure at 650°C is 7.1 bar as per 1.14 group materials.
Can this flange sustain 28.1 bar at 650°C as indicated in table A-1 of ceiling pressure?
Appendix A sets out how to establish the ratings for flanges given various factors including material properties. If your material was somehow much better than what was assumed you could calculate a higher pressure, but only up to the maximum ceiling pressures.
If you want 28.1 at 650C then you need to use group 2.12, 3.6, 3.9, 3.15
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
