Perry Johnson Registrars, Inc | UKASANABITAR
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Custom Ball Valve Seats

Carbon-graphite ball valve seats manufactured by Metallized Carbon Corporation are used in valves and designed to handle hot liquids or hot gases. The temperature range for Metcar carbon-graphite ball valve seats is from approximately 350°F, (where plastic seats can not be used because they start to soften), to over 800°F in oxidizing environments, (where high temperature carbon-graphite materials start to oxidize). Metcar carbon-graphite seats are also used for “fire safe” ball valves in the petroleum industry. These valves must operate freely after a simulated fire test where the valve is heated to 1400-1800°F for at least thirty minutes.

Because of its high degree of chemical compatibility carbon-graphite ball valve seats are utilized by many manufacturers in the most severe chemical environments.

The ball valve seats are produced by shrink fitting a carbon-graphite ring into a metal retaining ring. After shrink-fitting, the carbon-graphite is pre-stressed in compression and exhibits the same coefficient of thermal expansion as the metal retaining ring. The concave face of the carbon graphite ring is polished to make a pressure tight fit with the ball, and the back face of the carbon-graphite is lapped flat to make a pressure tight fit with the valve housing.

Metcar’s technical staff can recommend the appropriate material for your application.



Over 150 grades of our proprietary carbon/graphite METCAR material are available. Our engineers will select the optimum grade based on application, environment, temperature, etc.

Retaining Ring Material

Carpenter Alloys


Stainless Steels



Temperature Rating 2

350 to 800°F (in oxidizing environments) ºF


Metcar Physical Properties
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