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API Three Pieces Carbon Steel Flanged Motorized trunnion ball valve China Factory

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NORTECH is one of the leading China Motorized trunnion ball valve Manufacturer & Supplier.

Motorized trunnion ball valve


API 6D,API 607 Firesafe,NACE MR0175, ATEX Certified.

Body:Cast steel,Forged steel


Pressure rating:Class150-2500lbs

Manual operation,Pneumatic operation and Electric operation.

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What's Motorized trunnion ball valve ?

 Motorized trunnion 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.


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. This is particularly advantageous when the ball valve is actuated because it reduces the size of the actuator and hence the overall costs of the valve actuation package. 

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).

cast trunnion mounted ball valve

Main features of NORTECH Motorized trunnion 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.

fireproof stem
fireproof seat
double block and bleed(DBB)
double sealing
double sealing 2

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

blow out stem

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. 

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

extension stem
sealant injection device

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 of 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.

5.Anti-static Structure

The ball valve is designed with the anti- static structure and adopts the static electricity discharge device to directly form a static channel between the ball and body through the stem,so as to discharge the static electricity produced due to friction during the opening and closing of ball and seat through the pipeline,avoiding fire of explosion that may be caused by static spark and ensuring system safety.

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 released 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 (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.

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.

safety relief device

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

seat structure 01

Principle drawing of ball valve cavity pressure relief to the upper stream and down stream sealing

seat structure02

Specifications of NORTECH Motorized trunnion ball valve

Trunnion Ball Valve Technical Specifications

Nominal diameter


Connection Type


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


Seat material


Working temperature

Up to 120°C for PTFE


Up to 250°C for PPL/PEEK


Up to 80°C for NYLON

Flange end


BW end

ASME B 16.25

Face to face

ASME B 16.10

Pressure temperaure

ASME B 16.34

Fire safe&anti-static


Inspection standard


Exposion proof


Type of operation

Manual gearbox/Pneumatic actuator/Electric actuator

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Application of NORTECH Trunnion mounted ball valves

This kind of Trunnion Mounted 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,


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