High Quality Factory Wholesale Ball Valve Trunnion mounted Ball Valve
What's ball valve?
The ball valve is a form of quarter-turn valve which uses a hollow, perforated and fixed/supported ball to control flow through it.
A trunnion mounted ball valve means that the ball is constrained by bearings and is only allowed to rotate, the majority of the hydraulic load is supported by the System constraints, resulting in low bearing pressure and no shaft fatigue.
Advantages of trunnion ball design is the lower operating torque, ease of operation, minimized seat wear (Stem/ball isolation prevents side loading and wear of downstream seats improving performance and service life), superior sealing performance at both high and low pressure (a separate spring mechanism and upstream line pressure is used as the sealing against the stationary ball for low pressure and high pressure applications).
The pipeline pressure drives the upstream seat against the stationary ball so that the line pressure forces the upstream seat onto the ball causing it to seal. The mechanical anchoring of the ball absorbs the thrust from the line pressure, preventing excess friction between the ball and seats, so even at full rated working pressure operating torque remains low.
Main features of NORTECH ball valve
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. Another function of the discharge device is that the valve seat can be checked if there is a leakage during the test. In addition, the deposits inside the body can be washed through the discharge device.the discharge device is designed 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 metal 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.
Sealant Injection Device
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 tightened.In addition, the piston effect of valve seat is designed properly,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 released 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
8.Double Sealing (Double piston)
The trunnion pipeline ball valve can be designed with the double Sealing structure before and after the ball for some special service conditions and user requirements. It has double piston effect. Under normal condition,the valve generally adopts primary sealing.When the primary seat sealing us damaged and causes leakage,the secondary seat can play the function of sealing and enhance the sealing reliability. the seat adopts the combined structure.The primary seal is metal to metal seal.The secondary seal is fluorine rubber O ring that can ensure the ball valve can reach the bubble level sealing. When the pressure differential is very low,the sealing seat will press the ball through the spring action to realize primary sealing. When the pressure differential rises,the sealing force of seat and body will increase accordingly so as to tightly seal the seat and ball and ensure good sealing performance.
Primary sealing: Upstream.
When the pressure differential is lower or there is no pressure differential, the floating seat will move axially along the valve under the spring action and pish the seat towards the ball to keep tight sealing. When the of valve seat is higher than the force exerted on the area A1,A2- A1=B1.Therefore,the force in B1 will push the seat towards the Ball and realize tight sealing of the upstream part.
Secondary sealing: Downstream.
When the pressure differential is lower or there is no pressure differential,the floating seat will move axially along the valve under the spring action and push the seat towards the ball to keep tight sealing. When the valve cavity pressure P increases,the force exerted on the area A4 of valve seat in higher than the force exerted on the area A3,A4- A3=B1.Therefore,the force on B1 will push the seat towards the ball and realize tight sealing of the upstream part.
9.Safety Relief Device
As 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 NPT 1/2. 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 not 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 Stream
As 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, he ball valve ith the special structure is recommended to meet the requirements of automatic pressure relief and ensure no pollution to the environment.In the structure,the upper stream 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 stream,so as to avoid the danger caused by cavity pressure.When the primary seat 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
Principle drawing of ball valve upstream and downstream sealing
Principle drawing of ball valve cavity pressure relief to the upper stream and down stream sealing
12.Corrosion Resistance and Sulfide Stress Resistance
Certain corrosion allowance is left for the body wall thickness.
The carbon steel stem,fixed shaft,ball,seat and seat ring are subjected 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’s requirements,the valve materials can be selected according to NACE MR 0175 / ISO 15156 or NACE MR 0103,and strict quality control and quality inspection should be carried out during the manufacturing so as to fully meet the requirements in the standards and meet the service conditions in sulfurization environment
11.Blow-out Proof Stem
The 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.
Blow-out Proof Stem
13.Extension Stem
As for the embedded valve,the extension stem can be supplied if ground operation is required.The extension stem is composed of stem, sealant injection valve,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 valve driven through electric,pneumatic and pneumatic – hydraulic actuators,the extension stem length should be from the center of pipeline to top flange.
Schematic diagram of extension stem
Specifications of NORTECH ball valve
Ball Valve Technical Specifications
|
Nominal diameter |
2”-56”(DN50-DN1400) |
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Connection Type |
RF/BW/RTJ |
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Design standard |
API 6D/ASME B16.34/API608/MSS SP-72 ball valve |
|
Body material |
Cast steel/Forged steel/Cast stainless steel/Forged stainless steel |
|
Ball material |
A105+ENP/F304/F316/F304L/F316L |
|
Seat material |
PTFE/PPL/NYLON/PEEK |
|
Working temperature |
Up to 120°C for PTFE |
|
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Up to 250°C for PPL/PEEK |
|
|
Up to 80°C for NYLON |
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Flange end |
ASME B16.5 RF/RTJ |
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BW end |
ASME B 16.25 |
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Face to face |
ASME B 16.10 |
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Pressure temperaure |
ASME B 16.34 |
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Fire safe&anti-static |
API 607/API 6FA |
|
Inspection standard |
API598/EN12266/ISO5208 |
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Exposion proof |
ATEX |
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Type of operation |
Manual gearbox/Pneumatic actuator/Electric actuator |
• ISO 5211 mounting pad compatible for various type of actuators;
• simple structure,reliable sealing and easy maintenance.
• anti-static and fire safe design.
• ATEX certification for explosion proof.
Product Show:
Application of NORTECH ball valve
This kind of Ball Valve is widely utilized in the exploiting, refining and transporting system of oil, gas and mineral. It can be also utilized to produce chemical products, medicine; production system of hydroelectricity, thermal power and nuclear power; draining system,
