Length through Hub & RTJ Height of Non-STD 2500# WNRF flanges

[Shanamo]

Hello!!!
Dear Friends,
I am new to this forum.Actually,I am having a problem with deciding the length through hub of WNRF flanges while designing as per App-2.Where in code can I get the reference for the requirement of g1,g0 and length through hub.
Moreover,my other query is what should be or how to determine the RTJ height for 2500# non- standard WNRF flange( 30 Inch )?As the information on this size and rating is not mentioned in ASME B16.47.
Please help me out of this problem.

Thanks in advance.
Shanamo

 

[SnTMan]

Shanamo, Appendix 2 places some restrictions on slope of the hub, otherwise these dimensions are up to the designer. go will normally be set to match the mating cylinder. g1 will be equal to go + 1/4 or 1/2 inch. h will normally be 1 to 2 inch. It depends. These dimenison will have an effect on flange thickness as well. You trade off longer hub (additional metal machined away) for thinner flange ring. g1 gets too big it pushes your bolt circle out.

Don't know anything to offer on your RTJ, contact a gasket maker maybe?

Regards,

Mike

 

[Shanamo]

Hello SnTMan,
Thanks for the response.
Pls. make this a bit more clear.This h will be 1 to 2 inch plus g0 or only 1-2 inch? Because sometimes this hub length might be too short to meet App-2 requirement.
Thanks,
Shanamo

 

[SnTMan]

Shanamo, I did neglect to say that Appendix 2 does require that h be >= to 1 1/2 go. You of course have to meet that.

So suppose your g0 is equal to 1/2 inch. A typical hub might then be q1 = 11/16 or 3/4, h = 1 to 1 1/4. Or to put it more generally g1, might equal g0 + 1/4, h = 2 * g0.

As I said the exact hub dimensions affect, of course, stresses in the hub, and also flange ring portion stresses (thickness). Hopefully, you have a flange design program of some sort that you can evaluate overall effect of various hub dimensions.

As you can see from the design equations hub dimensions affect a great deal of the subsequent calculations. I don't know of any way to truly "optimize" the hub dimensions effect on overall flange design, whatever "optimize" may be chosen to mean.

Often it is "better" to use a shortish hub, so as to minimize chips (scrap) in the machining of the flange, even at the expense a slightly thicker ring. Or to put it another way, minimize the rough forging weight.

Regards,

Mike

 

[SnTMan]

Might also add that g1 is not required to be > go, i.e. the hub may be straight.

 

[Shanamo]

Thank you SnTMan.