RF vs FF flange connection

We have 12"control valve raised face flange and we have only flat face flange option in our spec as per class sheet.Flange rating is 150#.
Can we connect both flanges?? If yes,What about gasket.?? And where it is written??

So I have a question, this piping spec is it for steel pipe or something like FRP or HDPE?

spec is for steel pipe..

We have 12"control valve raised face flange and we have only flat face flange option in our spec as per class sheet.Flange rating is 150#.
Can we connect both flanges?? If yes,What about gasket.?? And where it is written??

It is recommended and best practice to order two RF flanges for the two sides of your CV. That is why we have spec breaks in pipe material specs/indexes. In my opinion, IF YOU HAVE ALREADY ORDERED the flanges it would not make a huge difference if you match the RF with FF flanges. But before that check your gaskets available compression area/surface. check to see if your available surface is all covered by the RF side which is your CV side obviously. If it was covered then you have no dramas matching these two types of flanges. Share with us your experience.

Alex

I agree with AlexPE completely! IF this is truly a steel spec then I'd try for the raised face flanges ...just to keep the connection "clean" (everything as it's suppose to be). However because it is a steel spec then it wouldn't matter if you matched a raised face flange to a flat ace flange. I'd suggest using a raised face gasket, because the only compression you'll get is around the raised faced flange.

We have 12"control valve raised face flange and we have only flat face flange option in our spec as per class sheet.Flange rating is 150#.
Can we connect both flanges?? If yes,What about gasket.?? And where it is written??

If i remember exactly ASME B31.3 allow you machine the surface gasket to match your FF gasket. But in this situation i dont think machine surface flange of vavle is a good choice.

Lam