Trunnion mounted ball valve:
The body construction precludes the internal disassembly at site. The complete replacement on the upper stem seal can be achieved with the valve installed without pressure.
Forging body and bonnet Ball
The material shall conform to the requirements of the ASTM standard. In acid service condition, the material shall conform to ASTM but also NACE MR 0175. Hardness is less than 248HV(22HRC).HIC,SSC tests are conducted.
The welding temperature field distribution is calculated.
Ball
Use forging solid sphere. Soft sealing ball valve plating ENP and hard sealing ball valve sphere spraying TCC, NI60, and STL.
Stem
The stem is separated from the ball. It is blow-out proof, properly obtained with an integral collar in the bottom of the stem.
Stem Seal
The stem is separated from the ball. It is blow-out proof, properly obtained with an integral collar in the bottom of the stem. Sealing system can be defined triple: two static o-rings seal the stem, plus a third graphite retained by the adaptor flange. This ultimate seal can be replaced when the valve is in line and in closed position.
Emergency stem and seat sealant injection
In case of emergency, when sealing materials (seat sealing and stem o-ring) are damaged or decomposed by fire or other accidental causes, a sealant injection into fittings on both stem and seat prevents leakage until the primary seal is restored.
Sealing Principle of valves less than 6"
The sealing between the seat and the ball is performed by a plastic polymer insert. The choice of this soft sealing is depending on the service conditions. The initial seal, at low differential pressure, is obtained by the spring loaded floating seats (spring energized) which achieve independent sealing. Increasing the line pressure behind the upstream seat ring helps the seat spring load to force the Seat design upstream seat tightly against the ball.
Sealing Principle of valves more than 6"
The valve sealing use the soft seal with VITON. The plastic material is using to sustain the ball to decrease the friction. The choice of this soft sealing is depending on the service conditions. The initial seal, at low differential pressure, is obtained by the spring loaded floating seats (spring energized) which achieve independent sealing.
Sealing Principle of valves with hard sealing
For metal to metal seated valve, the ball and the seat surface are coated with STL, TCC, NI60 to increase hardness and erosion.
In low differential pressure, it is obtained by the spring loaded floating seats (spring energized) which achieve independent sealing.
Fire safe design and test
Fire safe is standard design of BVMC ball valve. Two o-ring and gland gasket prevent leak paths from the valve stem area. If fire deteriorate o-ring, gland gasket, the stem fire safe packing prevent fluid or gas leakage. Soft seat ball valve fire safe test (shown in the image) was witnessed and certified according to API 607 and API6FA - BS 6755 PT.2
Anti-static device
This device is a standard feature of BVMC ball valves. A coil spring thrusts a little sphere, providing earthed continuity between stem and other metallic components of valve (ball and body) in order to avoid sparks during turning of the stem for opening and closing the valve and prevent problems in case of use with flammable fluids and gas.
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STANDARD MATERIAL:
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