Relying on fairly simple design principles, pressure seal valves have proven their capability to handle increasingly demanding fossil and combined-

cycle steam isolation applications, as designers continue to push boiler, HRSG, and piping system pressure/temperature

envelopes. Pressure seal Valves are typically available in size ranges from 2 inches to 24 inches and ASME B16.34 pressure

classes from #600 to #2500, although some manufacturers can accommodate the need for larger diameters and higher ratings for

special applications.