How To Design Reducing Flange? 1

[mkmm]

I have a situation where an existing 16" ASTM 53 pipe needs to reduce from the 16" diameter to 12" and back to 16" in about 30" horizontal distance. The connection point is an existing 16" WNF, then need to install a 12" plug valve with a PLIDCO flange downstream and transition back to existing 16" WNF. Can a special reducing "flange" or plate be machined which has a 16" bolt circle on one side and a 12" circle on the other side to mate the the existing 16" flanged and mate to the new 12" plug valve?

Other Details
Located in a pit below grade with access of 25"x 60"
0.375 Wall Pipe
Code B31.3, 150# Class
How to Determine Thickness of "Special Flange" if feasable?
Thanks In advance for any suggestions
Service Jet Fuel

 

[unclesyd]

You can buy Reducing flanges.
I'm not quite seeing the spacing you require. Try and get with a producer of these flanges and see if you can live with the take out. If you are talking about a thick blind with a 16" thru hole bolt circle and 12" set in studs, this has been done. 16 to 12 is fairly close it would have to be checked for clearence and calculated. This would be no problem if it clears.
If you have to use a plate transition piece make sure everyone signs off on it.

You will not have any jurisdictional problems with a 150# class reducing flange.

If you have room a reducing spool piece can be fabricated from standard components. Flange-reducer-flange.

http://www.western-forge.com

They can supply the reducing flange.

 

[bvi]

If you cannot find a commerically available reducing flange for your situation, ASME B31.3 permits you to design a flange using the rules of Section VIII, Div 1, Appendix 2.

 

[imok2]

Any piping supply house should be able to accomadate you