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Trunnion Ball Valves
Technical Features
Design & Construction
Flow Control 14T/15T ball valves are of bolted body construction to simplify field repairs and maintenance.
Independent floating upstream and downstream seats. Spring loaded seats are always in contact with the ball and so provide an effective tight seal even at very low differential pressures.
All Flow Control 14T/15T ball valves are trunnion-mounted which permits ease of operation with low torques.
Self-lubricated P.T.F.E. impregnated steel bearing sleeves.
Seal/stem integrity is achieved by independent multiple seals. The upper seal can be replaced when the valve is in line and under pressure. Stem is separate from ball.
Fugitive Emission Packing Seal - Flow Control trunnion mounted ball valves include an independent multi seal system as a sensible economical solution to provide zero leakage against dangerous emissions.
Each ball valve has block and bleed capabilities with independent upstream and downstream seals which permit draining and venting of fluid from within the body cavity. Automatic body pressure release to down stream.
Bonnet construction allows ease of mounting extensions, gears and actuators.
Antistatic features ensure electrical continuity between stem, ball and body.
Firesafe to API 607 and/or BS 6755 part 2.
Valves are constructed to meet NACE MR-01-75 latest edition.
Piston Effect
The spring loaded seats can move slightly along the longitudinal axis of the valve. Upstream pressure is exerted over area A1 which is counteracted over area A2. The remaining differential force over area D pushes the seat tightly on the ball. Even when line pressure, PL, is low, the mechanical action of the springs pushes the seats onto the ball thereby achieving perfect tight sealing.
The independent spring loaded floating seat design eliminates excess pressure buildup in the body cavity by automatically relieving the pressure.
As pressure, PB, increases within the body cavity, the force exerted over area A3 is greater than that over area A4 and the resulting differential thrust over area D moves the seat against the action of the springs away from the ball thereby discharging the excess pressure downstream. The spring action then returns the seats onto the ball.
Pressure / Temperature Curve (Click to view) 36 Kb
