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  Fully Welded Underground Valve Body:The valve body is integrally welded from forged pipe sections and valve body forgings using fully automatic Submerged Arc Welding (SAW) or Gas Shielded Arc Welding (GTAW/GMAW). It has no middle body flange or bolted connections. 100% Radiographic Testing (RT) and Ultrasonic Testing (UT) are performed to completely eliminate external leakage paths. The design service life is 30–50 years, matching that of buried pipelines.

• No Anti-Corrosion Coating Required:The fully welded structure has no external leakage points, allowing direct buried installation without anti-corrosion coatings or cathodic protection.

• Soil Load Resistance:The valve body wall thickness and structural reinforcement are designed to withstand static soil loads and dynamic loads from ground traffic.

• Seismic Adaptability:Flexible welded joints and reinforced structures accommodate seismic activity and ground settlement.

• Water Ingress Prevention:The extension tube sealing system and fully welded valve body prevent groundwater intrusion and corrosion of operating mechanisms.

• Trunnion-Mounted Ball:The ball is secured in body bearings by upper and lower trunnions, maintaining precise positioning under high differential pressure, soil loads and temperature variations, avoiding uneven wear of sealing surfaces and ensuring long-term reliable sealing.

• Full Bore / Reduced Bore Optional:Full bore design allows smooth passage of pigs and intelligent inspection devices, enabling online pipeline inspection. Reduced bore design optimizes cost efficiency, lowering weight and operating torque.

• Double Seat Bi-Directional Sealing:Independent upstream and downstream seats provide bi-directional sealing. Seats are available with piston effect (self-relief) or double piston effect (DPE) design to meet cavity pressure management requirements under different operating conditions.

Buried Fully Welded Trunnion Mounted Ball Valve 3D Diagram

J-VALVESSPE can supply a range ofseat types and configurationsto meet specific process needs:

J-VALVES trunnion mounted ball valves standard seat ringsare soft-seated by the use of athermoplastic or elastomeric or Meta

Seats-Tungsten /Chrome carbide /ENP

Single Piston (SPE) , Double Piston effect (DPE) and Combination (SPE x DPE) seats are available.

Seat Princlple

Two independent seat rings grant the sealing, barrieragainst the line pressure actingon the upstream and downstreamsides of the valve which allows the valve tobe bidirectional.

A set ofcoil springs acting, between the upstream side ofeach seatring,andthe body,generate an uniform thrust on theseat which push the same against the ball and grant the sealingfeature with no orverylow pressureinthe line,when the line pressure increasethe thrust actingon theseat increases proportionally and the sealing leatureis granted throughout the fullpressure range.

The J-VALVES SPE trunnion mounted ball valves are available with Double

Block & Bleed in dependent oftheseat type.

Valve seating variations

Seat Design	Single piston effect (SPE)	Double piston effect(DPE)-DIB 1	Combined DIB 2
Bi-directional sealing	Yes	Yes	Yes
Body-Cavity Self relieving	Yes	No	Yes
Double Barrier	No	Yes	Yes (preferred direction only)

Single Piston Effect

Single piston effect (SPE) is the stand ard feature for theseat rings of the J-VALVES SPE trunnion mounted ball valves.

On a SPE seat ring:

The pressure ac tingon the upstream side ofthe seat ringgenerates aforce which push theseattowards the ball.The pressure actingon the downstream side ofthe seatring generates a force which pull theseatring away fromthe ball.

Anyoverpressure which may be generated by the thermal expansion of the fluid trapped in thebodycavity with the ballin fully closed position, will beautomatically dischargedinthe line on the lower pressure side.

Double Piston Effect

Double piston effect(DPE) is a stand ard feature fortheseat rings ofthe J-VALVES trunnion mounted ball valves & recommended forwelded body valves. Ona DPE seat ring, both the pressure acting on the upstream sideof theseatring andthe pressure acting on thedownstreamside of the  seatring, generatea forcewhich push the seattowards the ball.

With th is type ofseat ring,the eventual over press ure whichmay be generated by the thermal expansion ofthe fluidtrappedinthebodyeavitywith theball in fullyclosed position,can be discharged by the use of:

An external safetyrelief device.

The Double Piston Effect grants a double sealingfeature,iftheupstreamseat ringisdamaged, thedown stream seatgrant the sealingfeature of the valve.