What is a Flange Valve?

Flange Valve Connections

Flange valves are straightforward and easy to install and remove from an application. A flange valve connection is secured bolts. A gasket is put between the flanges to help seal the joint. If installed correctly, flange connections create a fluid-tight seal.

In this article we are going to explain flange valve connections, including how the ANSI pressure-rating system converts to PSI.

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. Undoubtedly, using an unfamiliar valve can be dangerous for you, your coworkers, and anyone else who visits the site.

Flange valves 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

We also code Kimray flange valves as “RF” (Raised Face) or “RTJ” (Ring-Type Joint). On Raised Face valves, the gasket surface of the flange is raised above the bolting circle face. A Ring-Type Joint 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.