What is a Flange Valve?

What is a Flange Valve?

A flange valve connection is a type of connection that uses a gasket between the flanges of a valve and pipe to seal the joint. It is secured with bolts, and if installed correctly, flange connections create a fluid-tight seal. 

These connections are straightforward and make it easy to install and remove valve from from any application.

Producers typically use flange valve connections on valves 3" and larger. 

What is a Threaded Valve? 

A threaded valve is a valve that is secured to piping by threads. A threaded valve may also be referred to as NPT valve or screwed end valve. 

Standard National Pipe Thread (NPT) is tapered, so as you make the connection between your valve and pipe, the farther you thread it on, the tighter it gets.  

Producers typically use threaded valve connections on valves 2" and smaller. This is because they are more cost-effective than flange valves. However, installation is challenging over 2" because they must be spun on and the weight of 3"+ valves makes this very difficult.  

Should You Use Thread Tape on Threaded Valves? 

Yes. When making the connection between pipe and valve, thread tape or pipe dope help make a good seal to ensure the process fluid stays inside the valve and piping where it belongs.   

Something else to consider is that at some point you will likely have to change the valve or piping.

Over time, threads have a tendency to gall and stick together, especially if you’re using Stainless steel threads.

When that time comes, you will be glad you used thread tape, because it resists this metal-to-metal sticking and makes it it much easier to break the connection.

How to Convert a Flange Valve ANSI Rating to PSI

It is critical to know the rating of what pressure your valve is for before putting it in line. Using an unfamiliar valve can be dangerous for you, your coworkers, and anyone else who visits the site.

Flange valve ratings are based on the ANSI Pressure Rating System. ANSI (American National Standards Institute) is the body that establishes the measurement standards in the United States. ANSI also works along with the ASME (American Society of Mechanical Engineers) to identify and communicate safe standards for a variety of mechanical measures.

Valves rated at different ANSI classes react differently as the pressure and/or temperature of the process fluid changes.

Here is a chart that converts valve ANSI ratings to PSI:

ANSI Pressure Class & PSI Chart

Class Carbon Steel Stainless Steel
150 285 psi 275 psi
300 740 psi 720 psi
600 1480 psi 1440 psi
900 2200 psi 2160 psi
1500 3705 psi 3600 psi

Download a quick reference sheet of this chart

We also code Kimray flange valves as “RF” (Raised Face) or “RTJ” (Ring-Type Joint).

What is a Raised Face Flange Valve Connection?

On Raised Face flange valves, the gasket surface of the flange is raised above the bolting circle face.

What is a Ring-Type Joint Flange Valve Connection?

A Ring-Type Joint flange valve will have a raised gasket face along with a ring groove that is machined in the face. This groove will allow for a steel ring gasket for flange mating.

If you’d like more information about which type of valve you need, contact your local Kimray store or authorized distributor.