Trunnion mounted ball valve is designed in accordance with API 6D featuring 3 PC split body, side entry or top entry design.Cast steel trunnion mounted ball valve is wide range of sealing material including PTFE, PEEK, DEVLON, NYLON, etc, Trunnion mounted ball valve can be used in working temperature range -46ºC~ 500ºC.Trunnion mounted ball valve is optional designed with Double block and bleed or double piston type. Trunnion mounted ball valve is equipped with sealant injection system for both stem and seats to allow external intervention to prevent seat or stem leakage. The top entry ball valve can be used for in-line maintenance services. 

Trunnion mounted ball valve structure feature as below:
1  Reliable seat seal

• For soft seated trunnion mounted ball valve, the use of elastic sealing ring structure design.When the medium pressure is small, the contact area between the sealing ring and the ball is small, and a larger specific pressure is formed in the contact between the sealing ring and the ball to ensure reliable sealing.When the medium pressure is large, with the elastic deformation of the seal ring, the contact area between the seal ring and the ball increases, so that the seal ring can withstand a large medium thrust and will not be damaged.
• For metal seated trunnion mounted ball valve, which adopt advanced technology of spraying, the seat and ball surface spraying hard material, when the assembly through the counterpart of the sealing surface grinding, which can achieve high hardness and roughness.And under medium pressure and seat back spring force, which can achieve zero leakage and long life.

2 Fire-safe structure 

• Trunnion mounted ball valve fire safe design function, accord with standard API 607、API 6FA

when the Trunnion mounted ball valve is on fire, ball valve seat ring is damaged, which can use fire metal convex platform structure, effectively control the ball valve temporary leakage .
                                                   On fire                                                                                After fire
            
 

• The fire safe function of the valve stem is mainly realized through the fireproof graphite material  
• The fire safe function of the valve body and bonnet seal is mainly realized through the fireproof gasket material 

3 Anti-blowout structure 

• Trunnion mounted ball valve stem adopts bottom installation method, sealing force of back sealing increases with medium pressure and which can ensure the reliable seal of rod under various pressure.
• Trunnion mounted ball valve stem anti-blowout structure design, even in the extreme cases such as the abnormal pressure raise in valve cavity and packing pressure plate failure, etc., which can also ensure the valve stem not blown out by medium.

4  Anti-static structure

• Between Trunnion mounted ball valve body and valve stem, with anti-static spring; between the ball and valve stem, with anti-static spring.

• Among body & ball & stem, the formation of anti-static channel, push the ball and seat  friction produces static electricity in the open and close process, through the body to the earth, and to prevent electrostatic spark,and avoid to cause fire or explosion danger.

5  Lubricated injection design 

• Seat & stem seal injection structure

When the seat & stem seal ring of Trunnion mounted ball valve is damaged, seal grease can be injected through the injection device to temporarily prevent leakage at the seat & stem seal.

• Stem injection lubrication structure

At the stem place, by injecting grease through the injection device, the lubrication effect of the stem and packing can be improved to reduce the Trunnion mounted ball valve on-off torque and improve the on-off effect.

  
                                         Seat injection structure                                                               Shaft injection structure    

6 PMSS/Primary hard seal, secondary soft seal

• Sealing principle

1. Seat primary hard seal, secondary soft seal; Achieve double sealing.
2. Hard seal to achieve high pressure seal, soft seal to achieve low pressure seal.
3. The seat is designed to be triangular shape for stable performance.
4. Suitable for large diameter or high pressure ball valve sealing structure.

• Sealing material

Soft seal ring：Viton AED,Hard Rubber；
Hard face material：ENP/Ni60/Ni55/STL/TCC；

• Different sealing structure design comparison:

No	Item	Primary soft seal Secondary hard seal	PMSS/ Primary hard seal Secondary soft seal
1	Advantage	Stable structure and convenient assembly;	Achieve double sealing, completely achieve zero leakage
		Lower cost	High pressure & large diameter, better sealing effect;
		Matching with a variety of seat materials, suitable temperature is wide	Light opening torque
2	Disadvantage	When high pressure & large diameter, considering the sealing effect, the opening torque increases;	Higher cost
			Once the hard seal is damaged, maintenance is inconvenient;
			Not applicable to high temperature
3	Application	Any working condition;	High pressure & large diameter, at normal temperature

7 DBB/DIB-1/DIB-2 Structure

•  DBB/DIB-1/DIB-2 Structure difference

No	Structure type	Structure name	Exhaust principle	Product application
1	DBB	Single piston effect Double blocking and bleeding and middle cavity dischage	Automatic pressure relief in the middle cavity, pressure into the two sides of the channel	The most frequently used structure at present;
2	DIB-1	Double piston effect Double blocking and double bleeding	Pressure relief can only be achieved through additional relief valve, pressure does not enter through the sides	Use in specific working conditions or customer requirements;
3	DIB-2	Single/Double piston effect Double blocking and Before valve to discharge	Automatic relief in front of the valve, pressure only into the inlet channel	When used to relieve pressure, the pressure must not go into the downstream condition of the pipeline. Valve with direction of flow, pay attention to the direction of installation; At present, by a lot of owners more accepted;

8 Low leakage structure

• Some toxic, flammable or explosive medium, medium leakage from the ball valve is not permitted.
• Ball valve low leakage seal test, meet ISO 15848 standard
• Low leakage ball valve design principle:

1. The Trunnion mounted ball valve body should be able to meet the requirements of helium gas test. As the molecular volume of helium is small and easy to permeate, the body material is the key point;
2. The sealing of Trunnion mounted ball valve body and bonnet belongs to static sealing, so good sealing gasket material should be selected;
3. The stem seal is a dynamic seal, which is easy to take graphite particles out of the packing during the movement of the stem. Special low-leakage packing should be selected to control the clearance roughness of the stem, packing box, pressing sleeve and so on;
 
9 Lock device
Trunnion mounted ball valve is usually designed with a keyhole structure so that customers can add a locking device as needed to prevent misoperation.