To overcome the difficulties associated with the replacement of conventional valves or the reconditioning of valve seats on larger sizes, GEM has launched the Oyster piston-type isolation/stop valve, which offers positive shut off and zero emissions. Suitable for general-purpose fluid use and in particular for steam and condensate duty where shut-off tightness is required, the GEM Oyster is available in a variety of materials with screwed, socket weld or flanged connections. The piston valve enables leaks over the seat or past the stem to be sealed without disassembling, removing the valve from the line or isolating the process fluid. A complete set of internal parts can be fitted without removing the valve from the line, thereby effectively returning the GEM Oyster to “as new” condition. Available in cast iron, SG iron, carbon or stainless steel, the GEM Oyster is classed as “soft seated” and provides class 6 isolation. With the GEM Oyster there is no requirement for double isolation, unless stipulated to meet site/local standards, as the valve provides 100% tight shut-off under all conditions. The GEM Oyster is available in all sizes ranging from 3/8in to 2in for the screwed option and 1/2in to 8in for flanged piston valves.