Available both in cast and forged steel, it has been designed to meet all the requirements of ASME, API and British Standards
The body-bonnet connection is made by a pressure seal gasket. Its pre-stress condition is achieved by means of bolts screwed to the bonnet flange.
Ends are normally butwelding although they can be also flanged on request.
All bodies are provided with integrally cast bosses, located and sized in accordance with ASME B16.34, which allow the provision of drain and by-pass connections, supplied on request.
Usually constructed in the same materials as the body, being designed so that the wall thickness always exceeds the requirement of API 600.
A back seat bush (13) is fitted inside the bonnet lower cavity, to provide a closure when de valve is fully opened. This permits the valve to be repacked while in service.
The bonnet has a deep stuffing box in which packing rings are placed.
Stuffing box is designed with sufficient space to allow lantern ring to be fitted.
The wedge is normally constructed in forged stainless steel for diameters up to 3", and in cast steel for larger sizes.
Wedge is commonly flexible, though it can be also solid. Guides are carefully machined for a smooth sliding in the body cast-in guides.
Contact faces are overlayed with stellite-6 (2 mm. ominimumn. thickeness).
The handwheel can be supplied either in cast construction of fabricated from steel tube.
The handwheel is designed to allow easy operation of the valve. Other types of control are available and, in some cases, are indispensable for a good operation, for instance:
Geared hammer handwheel