900# FF flanges ?
900# FF flanges ?
(OP)
We have a compressor that is fitted with 6" 900# FF flanged outlets. We are replacing some knockout drums that sit directly on the compressor outlets. On the new drums we are considering specifying 900# RF flanges for mating to the compressor. I know that you can easily bolt together 150/300# RF flanges up against FF flanges without leakage problems, you just have to be careful not to over stress the RF flange when tightening so that it doesn't bend.
Anybody have any suggestions ??
Anybody have any suggestions ??





RE: 900# FF flanges ?
Also, pls do not use RF flanges for tightening against FF flange of this high rating(900#)since this will increase the chance of leakage.
RE: 900# FF flanges ?
RE: 900# FF flanges ?
I ask a manufacturers’ rep about the full face and red rubber gaskets, after checking his answer was when they increased the pressure ratings on some models coupled with experience they saw no need to change the flanges or gaskets within certain operating parameters.
RE: 900# FF flanges ?
RE: 900# FF flanges ?
RE: 900# FF flanges ?
Common practice is to use an adapter spool to connect to the ajacent piping. Be sure to check the loads on the nozzle.
RE: 900# FF flanges ?
Having eaten crow its time to try to help you resolve your problem. As mention above it can be done. I wouldn’t recommend this method though.. There are several companies that make gaskets that will seal and have means to prevent to much travel, similar to a spiral wound but not requiring the gasket seating stress required for the spiral wound gasket.
There are other methods that could be used but I can not mention them on an engineering forum.
Two companies that you might discuss your problem with are.
www.selcoseal.com
www.helicoflex.com
My reference to machining a raised face on a full face flange was correct. The problem was my memory dropped out because the machining was on the down stream flanges of spool pieces that bolt to a boss on the compressor housing. This boss is still a acting as a FF flange (900) with set-in studs. I called and checked this morning to find out the about the gaskets and flanges. All the flanges bolted to the compressor, with exception of two, are FF with most of the gaskets being a Grafoil gasket with a wire insert. The two remaining are RF and have a spacer at the bolt circle to limit travel. All of the downstream flanges have been changed to a RF.
Having eaten crow its time to try to help you resolve your problem. As mention above it can be done. I wouldn’t recommend this method though.. There are several companies that make gaskets that will seal and have means to prevent to much travel, similar to a spiral wound but not requiring the gasket seating stress required for the spiral wound gasket.
There are other methods that could be used but I can not mention them on an engineering forum.
Two companies that you might discuss your problem with are.
www.selcoseal.com
www.helicoflex.com
After you checkout their websites give them a call. I have used both with great success on very difficult sealing jobs. My reference to machining a raised face on a full face flange was correct. The problem was my memory dropped out because the machining was on the down stream flanges of spool pieces that bolt to a boss on the compressor housing. This boss is still a acting as a FF flange (900) with set-in studs. I called and checked this morning to find out the about the gaskets and flanges. All the flanges bolted to the compressor, with exception of two, are FF with most of the gaskets being a Grafoil gasket with a wire insert. The two remaining are RF with a spacer at the bolt circle to limit travel. All of the downstream flanges have been changed to a RF.
Having eaten crow its time to try to help you resolve your problem. As mention above it can be done, though I wouldn’t recommend this method though.. There are several companies that make gaskets that will seal and have means to prevent to much travel, similar to a spiral wound but not requiring the gasket seating stress required for the spiral wound gasket.
There are other methods that could be used but I can not mention them on an engineering forum.
Two companies that you might discuss your problem with are.
www.selcoseal.com
www.helicoflex.com
After you checkout their websites give them a call. I have used both with great success on very difficult sealing jobs.
RE: 900# FF flanges ?
This time it really wasn't the operator.
RE: 900# FF flanges ?
So far as I know, there's no much difference in bolting torques if you're bolting a RF to a FF flange (unless you're talking a softer material, like ductile iron or bronze). Just because you've only got one half of the RF joint, you're still looking at the same compressive area on your gasket. You're also still looking at the same bending moment around the raised face of the mating flange as if it was bolted to another raised face. I'm actually looking at a drawing right now of a sour service Worthington compressor in which volume bottles are bolted directly to the cylinder. Cylinder flange is 4"-1500# FF, bottle is 4"-1500# RF. As for gasket material, that'll depend on your service, we normally use composite non-asbestos type gaskets. Best bet is check with the compressor manufacturer for a recommended material and bolt torque.