In addition to the standard features shown in the specific catalog brochures, the Sharpe Series 84
and 99 three-piece ball valves and Series 50 full-port split body ball valve are now available with
metal seats in three different configurations. These new configurations are intended for use in
applications requiring resistance to erosion, abrasion, corrosion, and high temperatures beyond the
capabilities of the currently available polymeric seat materials. Different seat and seal
configurations can be supplied, depending on the specific application. All configurations include
the basic combination of a Stainless Steel 316 ball which has been electroless nickel plated (ENP)
and SS316 seats hard-faced with Stellite 6. The ball and seats are precision machined and lapped
together to provide an extremely tight fit; seat leakage rates equivalent to FCI 70-2, Class V or VI
can be provided.
A high-strength SS17-4PH stem is also installed to withstand the higher torques associated with
metal seats and the typical applications where they are used. The normal polymeric thrust washer is
replaced by a Nitronic 60 thrust bearing. The three metal seat configurations are described below.
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Type A Seat Configuration:
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This configuration includes the standard metal seat with polymeric seat seals, body seals and stem packing. It is intended for use in highly abrasive or erosive applications where higher temperatures are not an issue. The service temperature limit for this configuration is 450°F (232.2°C).
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Type B Seat Configuration:
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In this metal seat configuration the polymeric seals are replaced with die-formed flexible graphite seat seals and stem packing. The body seal is spiral wound SS316/flexible graphite in the Series M50; die-formed flexible graphite in the M84/M99. This configuration extends the temperature capability of the metal seated valves to 600°F (316°C), while retaining resistance to abrasion and erosion. This configuration is suitable for On-Off staturated steam service up to 200 PSIG in Class 150 valves, and 600 PSIG in Class 300 valves (carbon steel construction).
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Type C Seat Configuration:
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This arrangement utilizes a downstream metal seat with a flexible graphite seat seal, as in the Type B, with the upstream seat spring-loaded against the ball to assist in downstream sealing, and to provide compensation for thermal expansion effects at high temperatures. Type C configurations are therefore unidirectional, and a flow direction arrow is provided on the valve body. The Type C configuration is suitable for temperatures up to 1000°F (538°C), and is recommended for high temperature fluids and gases, and is suitable for saturated steam to 720 PSIG.
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