Flat face and Raised face flanges.
Flat face and Raised face flanges.
(OP)
Dear flange experts.
I´d like to know if it´s possible to mate ANSI B16.5 raised face flanges with ANSI B16.1 flat face flanges.
I have carbon steel pipes with ANSI B16.5 A105, class 150 and 300 raised face flanges, and want to install betwen them OS&Y cast iron valves (ASTM A126 class B) with ANSI B16.1 flat face flanges (Which I suppose are the most common flanges for cast iron accesories).
So my questions would be:
1. Is it OK to mate flat face with raised face?. If not, what is the correct way to specify flat faced cast steel valve companions?
2. Is there an equivalency of ANSI B16.5 (class 150 and 300) and ANSI B16.1. flange dimensions?
Thanks a lot.
I´d like to know if it´s possible to mate ANSI B16.5 raised face flanges with ANSI B16.1 flat face flanges.
I have carbon steel pipes with ANSI B16.5 A105, class 150 and 300 raised face flanges, and want to install betwen them OS&Y cast iron valves (ASTM A126 class B) with ANSI B16.1 flat face flanges (Which I suppose are the most common flanges for cast iron accesories).
So my questions would be:
1. Is it OK to mate flat face with raised face?. If not, what is the correct way to specify flat faced cast steel valve companions?
2. Is there an equivalency of ANSI B16.5 (class 150 and 300) and ANSI B16.1. flange dimensions?
Thanks a lot.





RE: Flat face and Raised face flanges.
What's in your pipe, and what kind of plant is it? That'll determine what code applies. There are a great many steam systems with boiler safety valves that lift at 150 PSIG, but operate to maintain a header pressure of 125 PSIG. A huge number of these systems are just FULL of 125 CI components that, of course, don't meet code. The 150 flanges have their raised faces intact, they often use ring gaskets, and the fasteners are usually SAE Gr 5. (It's like "Can you spot all 75 mistakes in this picture?") There are some really "intersting" installations out there.
RE: Flat face and Raised face flanges.
The application...
The case is a power plant, located in Costa Rica. We are adding some lines to an existing fire water protection system. The pipe: A53 B (NPSs from 2 to 12), exposed, the valves: OS&Y gate valves for fire protection, we are not obligated to, but we try to follow NFPA criteria. We are used to B31.1 so it influenced too.
In the purchase specification we asked for the valves (like NIBCO OS&Y gate valves, 125lbs, including companion flanges ANSI B16.5 SO-RF with gasket and accesories. So with your comment, "looks" like we made the mistake of including the RF indication with no aclaration.
Reading your lines, we will try to ask the contractor to remove de RF (or we will have to remove ourselves), and of course, you may guess that I´m wondering how critical would it be to leave it RF.
Reading the NIBCO catalog for 125lbs valves they don´t say information about the flanges. We didnt ask for a specific class of flanges, just the ANSI B16.5 mate flanges.
Any aditional comment..?
RE: Flat face and Raised face flanges.
I don't think I know of any equipment manufacturers that stray very far away from their particular product, regarding code requirements. They usually list the various approvals they have from code bodies, and whatever standards their bit meets, but that's all. They're basically vendors, and leave it to the designer to ensure that the correct component is being selected for whatever the service is.
RE: Flat face and Raised face flanges.
The "Piping Handbook" also contains cautions about using RF steel flanges with cast iron flanges.
Usually the mistake is made with a cast iron pump face and steel piping flanges.....When the flanges are tightened, th casing cracks. I would remove the RF from the flanges......an experienced piping contractor should be able to do this.
If your boss is putting pressure on you, have him take responsibility if there are any cracks.
My opinion only....
MJC
RE: Flat face and Raised face flanges.
RE: Flat face and Raised face flanges.
BUT if your in a pinch, and don't have time to remove the RF of the steel flange, you can make a spacer that fits around the outside of the RF section. This spacer will need holes cut for the stud-bolts and the spacer has to be the same thickness as the height of the RF section (1/16" approx.). Essentially your making a FF adaptor for a RF flange. The one I had to make was out of brass, so easy to fabricate. Hope this helps! ...Mark
RE: Flat face and Raised face flanges.
Regards dugal