Our trunnion-mounted ball valves offer increased value by incorporating advanced design features.
Design Features
◆ Vertical split three piece body Can be disassembled without special tools, allows maintenance and repair of all inner parts.
◆ Trunnion mounted ball Maintenan ce-free PTFE-coated bearings give low operating torque.
◆ Floating pressure-supported single piston self relieving seat rings, soft seated The self relieving seat ring design prevents inadmissible overpressure in the body cavity.
◆ Anti Blow out Stem
Prevents stem ejection by internal pressure when the stem packing retainer has been removed.
◆ Double Block and Bleed
Both in open and closed position of the ball the body cavity is isolated from up- and downstream line pressure. This allows double block and bleed testing of the valve seals.
◆ Drain Port
Enables draining the cavity and double block and bleed testing.
◆ Anti Static Design
Prevents the building up of static electricity. This allows to use the valve also in explosive atmospheres.
◆ Fire Safe Design, Fire Tested
Seat-to-body seals, stem packing and body seals are backed up with graphite se als. Fire tested according to international standards.
Trunnion-mounted ball
The ball is fixed and the seat rings are floating,free to move along the valve axis.
Side load generated by the pressure acting on the ball is absorbed by bearings.
At low pressure the seat sealing action is achieved by the thrust of the springs acting on the seat rings
As the preassure increases the fluid pressure pushes the seat rings against the ball.
Floating Self-relieving Seat Rings
Two independent floating seat rings assure the bi-
directional tightness of the valve.
The seats are carefully designed to minimize the
torque required to operate the valves without losing
sealing power,which is assured from zero differential pressure to the valve's maximum rated
pressure.
Self-relieving Seat are supplied as a standard feature.Double piston or combination seats(self-relieving/upstream/double piston/downstream)can be supplied on request
Independent ball and stem
The ball and stem are independent to minimize the affect of the side thrust generated by the pressure acting on the ball.
Anti-static design
The electrical conductance continuity between all the metallic components is guaranteed and
cetified
Low emission valves
Accurate machining of stem and bonnet sealing surfaces ensures compliance with the most severe pollution contrl regulations
Special"live"seals are available on request.
Double block & bleed
The double block and bleed feature,both with the ball
in the fullyclosed or fully open position,is a standard
feature.
STEM SEALING
Two O-rings and one graphite gasket ensure the stem seal.The graphite gasket can be replaced
while the valve is under pressure and with the ball in any position, by removing the adaptor
plate, after having released anypressure that may exist between the upper O-ring and the
graphite gasket, through the grease injection fitting hole.The O-rings can be replaced with the
valve in fully open or fully closed position by removing the stem cover after having released
all the pressure in the body cavity.
ANTI-BLOWOUT STEM
Stem is retained by the stem cover. Other designs available on request
BODY SEALING
The double sealing action of O-rings and graphite gaskets in all the static joints of the body
components, ensures zero leakage and the Fire Safe feature. Lip- seal rings and/or graphite
gaskets can be used for special service.
EMERGENCY SEALANT INJECTION
Each valve is supplied c/w emergency sealant injection feature located between the upper O-rings
and the graphite gasket. Emergency sealant injection feature on seats is available on request
only, for 6" full port and larger. Emergency grease injection features are not available on
low and high temperature valves.
STANDARD
SINGLE PISTON EFFECT
(SELF-RELIEVING SEATS)
Fluid pressure, both upstream and downstream, creates a resultant thrust that pushes the seat
rings against the ball.
Fluid pressure acting in the body cavity creates a resultant thrust that pushes the seat rings
away from the ball.
The single piston design permits the automatic release of any overpressure in the body cavity
when the valve is in the fully open or fully closed position, therefore the seat rings are
"self-relieving".
OPTIONAL
DOUBLE PISTON EFFECT
Fluid pressure, both upstream and downstream, as well as in the body cavity creates a resultant
thrust that pushes the seat rings towards the ball.
Valves with double piston effect seat rings require a relief valve in order to reduce the
build-up of overpressure in the body cavity.
