FC type valves are full-bore valves designed and manufactured according to API 6A and NACE MR0175 standards. They are suitable for standard double-end flange connections, threaded connections, and feature a special one-piece valve body construction. Below are the standard characteristics of FC gate valves:
The seal between the valve plate and the valve seat, and between the valve seat and the rear valve seat, is a metal-to-metal seal.
The simplified gate and seat assembly minimizes the number of components. An improved transmission thread between the gate and stem allows the gate to move back and forth, up and down, achieving a seal with the seat.
The gate and seat assembly is bidirectionally sealed, and the gate and seat can be reversed for use to extend their service life.
The valve stem’s sealing boss can achieve a seal with the valve cover, isolating the packing box from the pressure source. This allows the valve stem seal to be replaced even when the valve is under pressure in the field.
A non-lifting valve stem prevents pressure build-up in the valve chamber and the discharge of grease from the valve chamber.
All FC type valves feature a special design with a metal-to-metal seal, including a grease injection valve with a check valve. The valve stem, gate, and seat are all lubricated through this grease injection valve. For safety, this grease injection valve is located downstream of the valve stem back seal. The sealant or grease outlet does not extend directly into the valve cavity.
The seal between the valve body and the bonnet is pressure-activated. Valves with working pressures of 10,000 psi and 15,000 psi use BX-type metal bonnet rings; valves with working pressures of 3,000 psi and 5,000 psi use flat, compression-type metal gaskets.
These valves fully comply with API 6A material and temperature ratings, and additional special adjusting shims are available upon request. For valves of standard sizes and pressures, reduced-hardness bonnet bolts can be provided without lowering the operating pressure.
With slight modifications, FC type valves can meet the requirements of API 6FA fire safety.
The special non-rubber stem seal design allows the standard rated temperature of the FC gate valve to be increased from -60℃ (-75℉) to 176℃ (350℉), and even below -60℃ (-75℉). However, these rated temperatures are not applicable to all operating pressures.
Large-diameter FC valves can be equipped with additional force-saving mechanisms to reduce valve operating torque.
For the materials and descriptions of valve components, please refer to the material list for the valve assembly.
