Cast Trunnion Ball Valve
Cast Trunnion Ball Valve are manufactured to the latest
edition of API Standard 6D and tested to API Standard 598.
Cast Steel Trunnion Ball Valve are manufactured to the latest
edition of API Standard 6D and tested to API Standard 598.
– Structure : 2 pieces or 3 pieces body
– High shut-off sealing mechanism and low torque operation
– Block and bleed function
– Self-cavity pressure relief
– Fire safe design
– Blow out proof stem construction
– Anti-static design
– Locking device (for lever handle operation)
– ISO 5211 actuator mounting
– Emergency grease injection (option)
– PN design can be available”
– ASME CL150,300,600
– -196ºC ~650ºC
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 Prevent the fluid at the inlet and outlet to Recognize double block Purpose. 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 TorqueThe 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 metal bearing to reduce the friction coefficient to the lowest in conjunction with the high intensity and high fineness stem.
3. Emergency Sealing DeviceThe 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 DesignIn case of fire during the use of valve, the seat ring made of other non-metal materials will be decomposed and damaged under high pressure and cause higher leakage. The fireproof seal ring is set between ball and seat so that after the valve seat is burnt, the medium will push the ball rapidly towards the downstream metal seal ring to form the auxiliary metal to metal sealing structure, which can effectively control valve leakage. In addition, the middle flange sealing gasket is made of metal wound gasket, which can ensure sealing even under high temperature. The fireproof structure design of floating ball valves conforms to requirement in API607, API6FA, BS 6755 and other standards.
5. Anti-static StructureThe 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 Electrical energy Made Merited to friction Throughout the Starting and closing of ball and seat through the pipeline, avoiding fire or explosion that my be caused by static spark and ensuring system safety.
6. Reliable seat sealing structureThe 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 valves seat is realized by spring pre-tightening. In addition, the piston effect of valve seat is designed 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. The upstream side: When the seat moves axially along the valve, the pressure P exerted on the upstream part (inlet) produces a reverse force on A1. As A2 is higher than A1, A2-A1=B1, the force on B1 will push the seat to the ball and realize tight sealing of the upstream part. The downstream side: Once the pressure Pb inside the valve cavity increases, the force exerted on A3 is
higher than that on A4. As A3-A4=B2, the pressure differential on B2 will overcome the spring force to make the seat release from the ball and realize pressure relief of valve cavity to the downstream part.Afterwards, the seat and ball will be sealed again under the spring action.
8. Double Sealing design structureAccording to some special working conditions and customers' requirement, our company has provided the trunnion ball valve with the double sealing design structure, i.e. seat sealing in front of the ball and seat sealing behind the ball, thus the reliable sealing of the valve is ensured because the valve can perform normally even if one of the effective sealing designs becomes lost due to the abnormal condition. Regarding the seat in front of the ball, the piston effect formed by the are a difference between D1 and D2, plus the pre-tightened force of a spring would cause the seat in front of the ball by the pressure difference of the medium before and after the valve to touch the ball closely to form the tightness, of which the sealing force will become bigger as the pressure difference gets higher. Regarding the seat after the ball, the piston effect formed by the area difference between D2 and D3, plus the pre-tightened force of a spring would cause the seat behind the ball to touch the ball closely to form the tightness, of which the sealing force will become bigger as the pressure difference gets higher.
9. Safety Relief DeviceAs the ball valve is designed with the advanced primary and secondary sealing that has double piston effect, and the middle cavity cannot realize automatic pressure relief, the safety relief valve must be installed on the body in order to prevent the danger of over-pressure damage inside the
valve cavity that may occur due to thermal expansion of medium. The connection of the safety relief valve is generally NPT1/2. Another
point to be noted is that the medium of the safety relief valve is directly discharged into the atmosphere. In case direct discharging into the atmosphere is not allowed, we suggest that the ball valve with a special structure of automatic pressure relief towards upper stream should be used. Refer to the following for details. Please indicate it in the order if you do no need the safety relief valve or if you would like to use the ball valve with the special structure of automatic pressure relief towards upper stream.
10. Special Structure of Automatic Pressure Relief Towards Upper SteamAs the ball valve is designed with the advanced primary and secondary sealing that has double piston effect, and the middle cavity cannot realize automatic pressure relief, the ball valve with the special structure is recommended to meet the requirement of automatic pressure relief and ensure no pollution to the environment. In the structure, the upper steam adopts primary sealing and the lower stream adopts primary and secondary sealing. When the ball valve is closed, the pressure in the valve cavity can realize automatic pressure relief to the upper steam, so as to avoid the danger caused by cavity pressure. When the primary sat is damaged and leaks, the secondary seat can also play the function of sealing. But special attention shall be paid to the flow direction of the ball valve. During the installation, note the upstream and downstream directions. Refer to the following drawings for sealing principle of the valve with the special structure.
11. Blow-out Proof StemThe stem adopts the blow out proof structure. The stem is designed with the footstep at its bottom so that with the positioning of upper end cover and
screw, the stem will not be blown out by the medium even in case of abnormal pressure rise in the valve cavity.
12. Corrosion Resistance and Sulfide Stress ResistanceCertain corrosion allowance is left for the body wall thickness. The carbon steel stem, fixed shaft, ball, seat and seat ring are subject to chemical nickel plating according to ASTM B733 and B656. In addition, various corrosion resistant materials are available for users to select. According to customer requirements, the valve materials can be selected according to NACE MR 0175 / ISO 15156 or Nace Mr 0103, and Rigid Good quality Manage and quality inspection Must be carried out Throughout the Producing so as to Completely Encounter the Needs in the Requirements and meet the Program Ailments in sulfurization Surroundings
13. Extension StemAs for the embedded valves, the extension stem can be supplied if ground operation is needed. The extension stem is composed of stem, sealant
injection valve (extended grease fitting), and drainage valve that can be extended to the top for the convenience of operation. Users should
indicate the extension stem requirements and length when placing orders.
For ball valves driven through electric pneumatic and pneumatic-hydraulic operations, the extension stem length should be from the centre of pipeline to top flange
– Ball Valve design according to API6D, BS5351, ASME B16.34
– Face to Face ASME B16.10, API6D
– End Flanged ASME B16.5/ASME B16.47
– Butt Welded ends ASME B16.25
– Fire Safety API607, API6A
– Inspection and test API598, API6D