It is designed according to API-600 and ASME B16.34 standards.
Closure member is wedge-shaped, assuring the seal tightness against high and low pressures. The wedge is made of cast material, with flexible or solid design depending on size and customer requirements.
Seat rings are screwed to the body, welded or not depending on size, and they can be machined in the body for valves in austenitic material. Both types are renewable, fulfilling all the international applicable standards.
Wedge-to-stem connection is made by means of a T-slot in the top of the wedge.
Its duty is stopping and starting flow, for non frequent operations and it cannot be used throttling the flow to avoid damaging the seat surfaces.