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CAST TRUNNION BALL VALVE
The trunnion ball valve is used to cut off or connect the media in
various of Class150~Class2500. The valves made of different
materials are suitable for various media such as water, steam, oil,
liquefied gas, natural gas, coal gas, nitric acid, oxidizer, urea
and etc. The driving modes include manual operation and electric
operation. The connection ends can be flange or butt welding.
STRUCTURAL FEATURES
1. Double Block And Bleed(DBB)
When the valve is closed and the middle cavity is emptied through
the discharge valve, the upstream and downstream seats will
independently block the fluid at the inlet and outlet to realize
double block function. Another function of the discharge device is
that the valve seat can be checked if there is any leakage during
the test. In addition, the deposits inside the body can be washed
and discharged through the discharge device to reduce damage to the
seat by impurities in the medium.
2. Low Operating Torque
The trunnion pipeline ball valve adopts the trunnion ball structure
and floating valve seat, so as to achieve lower torque under
operating pressure. It uses self-lubricating PTFE and sliding
bearing to reduce the friction coefficient to the lowest in
conjunction with the high intensity and high fineness stem.
3. Emergency Sealing Device
The ball valves with the diameter more than or equal to 6(DN150)
are all designed with sealant injection device on stem and seat.
When the seat ring or stem O ring is damaged due to accident, the
corresponding sealant can be injected by the sealant injection
device to avoid medium leakage on seat ring and stem. If necessary,
the auxiliary sealing system can be used for washing and
lubricating the seat to maintain its cleanliness.
4. Fireproof Structure Design
In case of fire during the use of valve, the seat ring, stem O ring
and middle flange O ring made of PTFE, rubber or other non-metal
materials will be decomposed or damaged under high temperature.
Under pressure of the medium the ball valve will push the seat
retainer rapidly towards the ball to make the metal seal ring
contact the ball and form the auxiliary metal to metal sealing
structure, which can effectively control valve leakage. The
fireproof structure design of trunnion pipeline ball valve conforms
to requirements in API 607,API 6FA,BS 7655 and other standards.
5. Anti-static Structure
The ball valve is provided with the anti-static structure and
adopts the static electricity discharge device to directly form a
static channel between the ball and body or form a static channel
between the ball and body through the stem, so as to discharge the
static electricity produced dut to friction during the opening and
closing of ball and seat through the pipeline, avoiding fire or
explosion that may be caused by static spark and ensuring system
safety.
6. Reliable seat sealing structure
The seat sealing is realized through two floating seat retainers.
They can float axially to block the fluid, including ball sealing
and body sealing. The low pressure sealing of valve seat is
realized by spring pre-tightening. In addition, the piston effect
of valve seat is desinde reasonably, which realizes high pressure
sealing by the pressure of the medium itself. The following two
kinds of ball sealing can be realized.
7. Single Sealing (automatic Pressure Relief In Middle Cavity Of
Valve)
Generally, the single sealing structure is used, that is, there is
only the upstream sealing. As the independent spring loaded
upstream and downstream sealing seats are used, the over-pressure
inside valve cavity can overcome the pre-tightening effect of the
spring, so as to make the seat release from the ball and realize
automatic pressure relief towards the downstream part.