Bonnet Flange Thickness 3

[newdell]

Can anyone help me how to determine the valve body/bonnet flange thickness? The flange is square with circular gasket. I was following the formulas in BPVC VIII, but I am not sure how to determine the flange outside diameter. Should it be the largest circle inside the square flange or outside the square? The results are quite different. Appreciate if someone can help!!!

 

[abscott]

Newdell,
I am not an authority on this subject but, I would take the conservative approach and use the largest circle inside the square. If you use the circle outside the square you are taking credit for metal that does not exist and this could cause gasket leakage problems.

More metal, but less risk.
Regards,
ABScott

 

[newdell]

Thank you very much for your response. I totally agree with you. But I was not sure if it violates the thickness rules by using the largest circle inside the flange.
For economical reasons, I would like to see if I can eliminate some extra weights by modifying the equations, or if there is some formula to use for a square flange which doesn't state in BPVC.

 

[JimCasey]

Body thickness criteria are addressed in ASME B16.34. This is obviously in accordance with the Boiler and pressure vessel code (B31.1) but more specialized. Gate valves are addressed there, and they have rectangular bonnets.

 

[unclesyd]

You might want to check this out.
Valve components.

http://www.techstreet.com/cgi-bin/detail?product_id=1171526

 

[newdell]

Thank you all for the helpful information. I'll go and check those standards.