Product Description
Fomen trunnion mounted ball valve has fixed by upper and lower shafts. Therefore, the ball does not float but the sealing ring is float. Usually it is suitable for high pressure industry application.
Whats the basic principle of Formen ball valve sealing? A sealing force is generated by seat spring pre-tightening force or medium pressure, so that the valve seat and the ball are pressed tightly, and the sealing ring produces elastic-plastic deformation to compensate for the relative deformation of the ball, the roundness error and surface roughness of the ball, to ensure the valve seat does not leakage.
Double block and bleed design (DBB), Self-relieving seats (Single piston effect)
The single piston effect is the standard design for Formen trunnion mounted ball valve. Pressure from both up-stream and down-stream sides push the seat rings against the ball.
If the force created by the body cavity, if the pressure exceeds the sum of pre-loaded spring force and up-stream or down-stream side force, then the seats are pushed away from the ball. So that the over pressure will be released automatically in the body cavity when the valves fully open or fully closed.
Double piston effect seats (DIB-1) (As optional)
Double piston effects are pressure energized in both directions. So the seat rings are always pushed against the ball by the pressure from up-stream or down-stream or body cavity.
If the up-stream seat fails, the down-stream seat can still ensure a tight seal. However, since double piston effect valves do not have the self-relieving function, the automatic cavity-pressure relief valve shall be provided
One self-relieving seat and one double piston effective seat.(DIB-2) (As optional)
If the force created by the body cavity pressure is exceeds than the sum of pre-loaded spring force and pipeline pressure force, the cavity pressure releases via the self-relieving seat, the double piston effect seat still functions a tight seal.
The DIB-2 has to installation in the same arrow direction of the Formen ball valve body Mark. If the user installs it in wrong position, the pressure will be bleeding on opposite position and reduce the valves service life.
Fire safe design
1.Stem leakage prevention, before fire happen, the leakage from the valve stem is prevented by O-ring seals and gasket. When fire happens, the O-rings, gasket has been destroyed. The graphite stem packing still can be prevents external leakage.
2.Seat leakage prevention, after the soft sealing materials has been destroyed by fire, the seat pre-loaded spring comes into contact with the ball to block the leakage, also a graphite seat gasket is compressed by the spring to prevent leakage between the valve body and seat.
Anti- Blowout Stem design
Formen ball valves stem is made separately from the ball. The lower end of the stem is designed with an intergral shoulder to be blowout-proof.
Anti-static Device
Its a standard feature of antistatic device for Formen ball valve. A spring-loaded pin assures the electrical continuity between the ball, stem and body to avoid sparking during the turning of the stem to open and closed the valve.
Emergency sealant injection plug
As for 6inch and larger Formen trunnion mounted ball valves, sealant injection plug will be installed on both the stem and seats. When the sealing materials are damaged, the leakage can be prevented by the sealant injected in to these plugs.
