Basic Gate Valve - Seating Materials

The seat and disc constitute the "heart" of a valve;  do most of its work.  The material from which these parts are made, therefore, becomes important.  The tougher the service, the more severe the demand on seating.  Valve manufacturers recognize this fact by providing a wider choice of seating materials as valves go up the pressure-temperature scale or are offered for more rigorous service.

For relatively low pressure and temperatures and for ordinary fluids, seating materials are not a particularly difficult problem.  Bronze and iron valves usually have bronze or bronze-faced seating surfaces, or iron valves may be all iron.  Nonmetallic "composition" discs are available for tight seating on hard-to-hold fluids such as air or gasoline.

As pressures and temperatures increase or as the service becomes severe, careful consideration must be given to many factors, no one which can be overemphasized to the detriment of others.  Long, trouble-free life requires the proper combination of hardness, wear-resistance, resistance to corrosion, erosion, galling, seizing, and temperature.  Nor does it follow that a satisfactory combination in one instance will serve equally well in all others.  Type of valve is a limiting factor, too.

Selection of seating materials for corrosive fluids, regardless of pressure-temperature, is almost endless.  Included are many types of alloys, as well as linings or coatings of many kinds.
 
 

Valve Catalog your best guide

Safest policy in specifying seating materials is in close adherence to valve manufacturer's recommendations, usually found in catalogs, otherwise supplied on request.