Raised Face Flange nd Flate fFace Valve
Raised Face Flange nd Flate fFace Valve
(OP)
We are replacing some isolation valve on the sea water cooling pipe lines size ranging 6" to 36". Due to some mix-up, the valves which are ordered as replacement are of 125 class Flat Face, where as existing valves and flanges are of 150 class Raised Face. We do not want to cut and replace the RF flanges to install the new FF valves due to internal coating on the pipe.
- Could some one please suggest if it is ok to use full face flat gasket for this situation i.e. RF pipe Flanges with FF valves in between them?
- Do we have to insert metallic annular spacer equal to the thickness of the raised face ( 1.6 mm ) to fill the gap created due to RF on the pipe flange? This spacer may provide necessary support to the FF flange.
- Will proper sealing be made to hold the 60 psig pressure.
- Does this situation violate any piping code? Appendix 'Y' of ASME div-1 sec. VIII allows spacer between the FF flanges.
- Is it technically feasible to fabricate spacer with thickness 1.6 mm?
- Could some one please suggest if it is ok to use full face flat gasket for this situation i.e. RF pipe Flanges with FF valves in between them?
- Do we have to insert metallic annular spacer equal to the thickness of the raised face ( 1.6 mm ) to fill the gap created due to RF on the pipe flange? This spacer may provide necessary support to the FF flange.
- Will proper sealing be made to hold the 60 psig pressure.
- Does this situation violate any piping code? Appendix 'Y' of ASME div-1 sec. VIII allows spacer between the FF flanges.
- Is it technically feasible to fabricate spacer with thickness 1.6 mm?





RE: Raised Face Flange nd Flate fFace Valve
Raised Face (RF) - The Raised Face is most common of all flange faces. The flange has a raised area machined on the flange face equal to the contact area of a gasket.
Flat face flanges are never to be bolted to a raised face flange. If you need to bolt a Forged steel flange to cast iron then you must call for the forged steel flange to be machined off to a flat face.
For more information on flanges, flange faces, gaskets and bolting see ht
pipingdesigner
www.pipingdesigners.com
RE: Raised Face Flange nd Flate fFace Valve
Please clarify, If macnining of the raiced face will enable him bolt FF to RF what is wrong with using a spacer same material as the RF flange as he suggested?
I feel if the sapacer can be machined to fit well it is ok.
If this violates any pining code please let us know.
Thanks
Abba.
RE: Raised Face Flange nd Flate fFace Valve
http://www.gouldspumps.com/pom_0007.html
He and others should also listen to what Piping Designer has to say.
PennPiper
RE: Raised Face Flange nd Flate fFace Valve
I'm frankly very surprised. As an ME you should know better than to hope that you can obtain the required facing finish on a shim or spacer that you have suggested for a raised face flange. As a Chem E who has the mechanical hands-on experience and the lathe abilities (still!) I don't think any engineer can machine the washer you're proposing (or defending) to the true thickness (1/16") face finish that will match the sealing and torque requirements of the flanged joint - and do it economically. Besides that, the proposal is just plain foolish and hazardous. I see no way that you can ensure that the washer face will line up true with the raised face to ensure that the compression forces on each flange will be evenly distributed.
The advice that pipingdesigner and pennpiper are giving is not only sound and logical - it's the safest manner to carry out a necessary procedure that comes up mainly when flanging up cast iron equipment to carbon steel piping. Otherwise, it should be avoided.
This subject has come up many times on the Forums (even with FRP & GRP pipe flanges) - and the logical answer is always the same.
RE: Raised Face Flange nd Flate fFace Valve
RE: Raised Face Flange nd Flate fFace Valve
RE: Raised Face Flange nd Flate fFace Valve
How come the use of a spool piece is not more frequently recommended, if at all?
We often use spool pieces to joing different size pipes (rather than a reducer) and different ANSI rated pipes (900# to 300#).
I don't see why a spool piece with FF on one end and RF on the other won't work?
"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?
RE: Raised Face Flange nd Flate fFace Valve
A good solution to the existing raised face flanges is to contact a company such as In-Place Machining, Inc. Look at http://www.inplace.com/machining/specialized.html. A company such as this can machine the flange faces without removing any piping.
Larry
RE: Raised Face Flange nd Flate fFace Valve
The assumption is that they are cast iron but since class 150 RF flanged valves were the intent, they wouldn't have been cast iron, so how bad did the valve order get botched?
If the valves a carbon steel, just use a suitable ring-cut sheet gasket, bolt it up and forget the spacer.
My 2ยข
NozzleTwister
Houston, Texas
RE: Raised Face Flange nd Flate fFace Valve
Larry
RE: Raised Face Flange nd Flate fFace Valve
Sorry for not giving it much thought, I have never encountred such a problem practically, I was only considering the low pressure service.
Thanks for pointing it out, I will quickly add that you are too hash in your response.
Abba
RE: Raised Face Flange nd Flate fFace Valve
what mechanic in a hurry is not going to drop, misplace or just ignore such a device. or worse yet, not center it properly?
we are trying to get rid of cast iron flanges in our storehouse since there have been instances where they have been mis-applied and later broken due to stresses when tightening the bolting.
not sure anyone has addressed if these valves are actually cast iron or not, but i am with Montemayor on this one. it is a bad practice. and bad practices lead to bad games.
with regards to harshness, i too am beginning to lose patience with bad ideas. everyone seems to think that having a special procedure for every installation is something that will be remembered down the road.
well, we can do thus and so if we only torque this combination to some number of pound feet or use special low strength bolts (there are some special ones for cast iron, btw) and we should be okay.
well, when Bubba comes along to tighten a flange and you ask him how much torque he is going to use, he'll likely say he's going to torque it till its tight.
maintainability in many cases comes down to repeatability and not special procedures tucked away in page 38 of volume 7 of some project notes.
ben, a ChemE with a lathe and an end mill in his garage.