Automated Trunnion ball valve

An automated trunnion ball valve is a quarter-turn isolation valve whose ball is anchored on upper and lower trunnion bearings and driven by an actuator - a double block and bleed valve built for large bore and high pressure. Spring-loaded seats seal both sides at a torque that stays near-constant as line pressure changes, so a 56 in. valve at Class 2500 still strokes like a small one. What decides whether it protects the line is the seat geometry (DBB vs DIB), the fire-safe and anti-blowout construction, and the actuator fail action specified around it.

Overview

• Design standard: API 6D
• Full port, reduced port
• One, two, three pieces or fully welded body
• Fire safe test certified (API607, API6FA)
• Anti-static, blowout-proof stem
• Double block and bleed
• Sealant injection on stem & seats
• Optional low emission design
• Top flanged to ISO 5211
• Optional double piston effect sealing(DIB)

Product range and configuration

Size:  2"~60"

Rating: 150#~2500#

Body:  Carbon steel, stainless steel, alloy

Trim:  A105N+ENP, 13Cr, F304, F316

Seal type: Soft or metal seat

Temp:  -196~500°C

Operation

Lever / Gearbox

Pneumatic Actuator

Electric Actuator

Hydraulic Actuator

Gas – hydraulic Actuator

Electric – hydraulic Actuator

Features

• Trunnion-supported ball. 
• Spring-loaded, self-energised seats. 
• Double block and bleed. 
• Cavity pressure self-relief. 
• Fire-safe construction. 
• Anti-blowout stem. 
• Anti-static path. 
• Actuator-ready. 
• Optional emergency sealant injection. 

Available automation solution

Remote Operated Valves (ROV)

Emergency Shut Down Valves (ESDV)

Motor Operated Valves (MOV)

Hydraulically Operated Valves

Gas Operated Valves

Materials and Principal Parts

For wet sour service, the body and trim are specified to NACE MR0175 / ISO 15156 - commonly A350 LF2 with low-temperature impact and a 22 HRC hardness cap - and that discipline must be written into the order before the steel is poured, because it cannot be added afterwards.

Trunnion vs Floating Ball Valve

The boundary between the two designs is not a preference - it is a pressure and size threshold. A floating ball valve relies on line pressure to push the ball onto the downstream seat, so the sealing force and the actuator torque both climb with pressure; past about NPS 8 at Class 300 the actuator needed to hold the seat becomes larger and more expensive than the trunnion valve it was meant to avoid. The trunnion ball valve removes that coupling by fixing the ball and energising the seats with springs, which is why it spans NPS 4 to 56 and Class 150 to 2500 and is the only one of the two that gives true DBB.

Applicable industry

Oil & natural gas transmission lines

Process control in oil, gas, chemical

Petrochemical application

Easier maintenance

Shut off media

Unsuitable for throttling

Water, oil & gas

Unsuitable for dry powder media

Quality, Testing and Standards

Every valve is tested assembled with its actuator where supplied, because a valve that passed alone proves nothing about the package. Shell, seat and cavity tests follow API 6D / API 598 procedures and are recorded against the valve serial number.

Standards in force at time of writing: API 6D (pipeline valves) and API 608 (process metal ball valves) for design, ASME B16.34 for pressure-temperature and wall thickness, API 6DX / ISO 5211 for actuator mounting, API 607 / API 6FA (and ISO 10497) for fire, API 598 and ISO 5208 for testing and seat leakage, ASME B16.10 for face-to-face, ISO 15848 for fugitive emission, and NACE MR0175 / ISO 15156 for sour service. Confirm the edition your purchase order requires - note that "Class VI per API 598" is a control-valve rating (ANSI/FCI 70-2) and does not apply to these on/off isolation valves.

Packaging, Lead Time and Payment

Packaging: actuator and bracket secured against transit shock; flange faces and the ISO 5211 pad protected; body cavity vent plugged; desiccant in the crate for sea freight.

Marking: valve tagged per API 6D with size, class, serial and trunnion/body material; actuator data plate retained for traceability.

Lead time: 7–15 days for standard configurations from stock; 20–35 days for engineered packages (special seat, DIB geometry, extended stem, SIL-certified assembly).

Shipping: FOB / CIF / DAP by negotiation from major Chinese ports; full documentation set with each shipment.

Payment: T/T 30% advance + balance before shipment, or L/C at sight for project orders.

Warranty: 18 months on the actuator and controls, 12 months on the valve body, from bill of lading; seal kits and trim spares recommended with each order.

Send us your size and class, bore, body and seat material, required seat action (SPE/DBB or DPE/DIB), maximum differential pressure, media and temperature, and the actuator type with failure position and control signals - our technical team will confirm sizing and return a quotation with lead time, typically within 24 hours. As a trunnion ball valve and actuation package supplier, GNEE quotes the complete valve-and-actuator unit; contact GNEE today for price and delivery.

Why Source from GNEE

As a valve-and-actuation package supplier, GNEE delivers the trunnion ball valve and its actuator as one tested unit - not two shipments that meet for the first time on site. Seat action, failure position and stroke time are reconciled across a single datasheet, with one point of responsibility from enquiry to commissioning support.

One matched package. Valve, actuator, mounting and controls sized together to your differential pressure and duty - one interface, one data sheet, one warranty.

Verified at the worst case. Actuator torque proven at minimum supply pressure, not nameplate; DBB/DIB proof and fire test demonstrated before dispatch where specified.

Standards-current documentation. EN 10204 3.1 certificates, API 6D / API 598 test reports and fire-test certificates as standard; SIL device certificate on request.

Export experience. 160+ customers across energy and pipeline markets; familiar with third-party inspection and destination documentation.

Responsive engineering. Control philosophy and actuator selection reviewed and confirmed within 24 hours of a complete enquiry.

FAQ

What is the difference between a trunnion and a floating ball valve?

A floating ball valve lets line pressure push the ball onto the downstream seat, so sealing force - and operating torque - rise with pressure; it stays practical up to about NPS 8 at Class 300, then the actuator needed to hold the seat becomes larger and costlier than the valve it was meant to avoid. A trunnion ball valve anchors the ball on upper and lower trunnion bearings, so spring-loaded seats press inward against a ball that cannot move sideways; the sealing force is largely independent of line pressure and torque stays near-constant. That is why trunnion designs cover NPS 4 to 56 and Class 150 to 2500, and why only a trunnion valve gives true double block and bleed.

Why does a trunnion ball valve need cavity pressure relief?

When the valve is closed, fluid trapped between the two seats in the body cavity can expand as temperature rises and overpressurise the cavity - a hazard a floating ball valve does not have, because it has no sealed cavity in the flow path. Trunnion valves use a self-relieving upstream seat (single piston effect): once cavity pressure exceeds the spring preload, the seat lifts off the ball and vents back into the line, then springs shut again. The relief is automatic and needs no external relief valve, so the body is protected without an operator on site.

What is the difference between DBB and DIB-1 / DIB-2?

DBB (double block and bleed) means both seats seal against the ball and the cavity between them can be vented to confirm isolation - typically the upstream seat is single-piston-effect (SPE), sealing with line pressure. DIB (double isolation and bleed) upgrades both seats to double-piston-effect (DPE), so each seat seals against line pressure from its own side and holds even if backpressure appears on the opposite side. Choose DIB-1 or DIB-2 when backpressure can occur on either side, or where the isolation duty is safety-critical; specify which in the purchase order because the seat geometry is different.

What actuator mounting standard applies to an automated trunnion ball valve?

The valve carries an ISO 5211 mounting flange (sometimes with API 6DX compliance for pipeline duty) so a pneumatic, electric or hydraulic actuator of the matching flange size and drive square bolts directly on without a custom bracket. The actuator is sized to the valve's breakaway and running torque at the actual differential pressure with a safety factor, not to a catalogue torque, so the assembly is supplied as one matched unit.

What is partial stroke testing and why does it matter?

Partial stroke testing moves the valve only 10–20% of its travel to prove it still responds, detecting a large share of stuck-valve failures without shutting the line down. On an automated trunnion ball valve it is done through a smart positioner or dedicated PST controller and directly supports SIL verification, because periodic proof of operability is what the safety calculation depends on. It is the standard way to keep a HIPPS or ESD final element creditable between full-stroke overhauls.

What seat leakage class applies to a trunnion ball valve?

Soft-seated versions are tested to ISO 5208 Rate A - zero visible leakage - and metal-seated versions to Rate D as the general isolation default; API 6D and API 598 are the test procedures. The leakage classes of ANSI/FCI 70-2, sometimes miswritten as "Class VI per API 598", belong to control valves and do not apply to these on/off isolation valves. Shell testing is at 1.5 times rated pressure and seat testing at 1.1 times.

How is the fail position of the actuator set?

The fail position is a process-safety decision, not a default: on loss of signal or air supply the valve drives to fail-closed (FC), fail-open (FO) or stays put, selected from the hazard or SIL study. A spring-return pneumatic or a battery/hydraulic-backed electric actuator reaches the safe position without external power; a plain electric actuator stays put unless a fail-safe module is specified. State the required fail position and the required closing time in the enquiry, because they decide the actuator type.

Which actuator type should I choose for my service?

Use an electric (motor operated) actuator where mains or instrument power is available and stroke speed is not critical; a pneumatic actuator where plant air exists and fast ESD is needed; a hydraulic or gas-over-oil actuator where no external power is available - notably remote pipeline block stations. Each route is a separate page on our site; the valve is the same trunnion ball valve, and the choice is made on the power source, fail action and stroke-time duty, not on the valve body.

What is the MOQ and lead time?

MOQ is 1 set - one valve-and-actuator package is a normal order. Standard configurations ship in about 7–15 days from stock; engineered packages with special seat materials, DIB geometry, extended stem or certified SIL assembly take about 20–35 days depending on scope. Confirmation of the exact schedule follows review of your specification.

What documents come with each valve?

Each valve ships with EN 10204 3.1 material certificates, API 6D / API 598 pressure test reports (shell 1.5×, seat 1.1×, low-pressure pneumatic 0.6 MPa), fire-test certificate where specified, and commissioning and maintenance manuals. Third-party inspection (SGS, BV, TUV or your nominee) and an IEC 61508 SIL device certificate for the actuator assembly can be supplied on request.

Can an automated trunnion ball valve be used in sour gas service?

Yes. Body, bonnet and trim can be specified to NACE MR0175 / ISO 15156 - for example A350 LF2 with low-temperature impact, hardfaced or 13Cr trim, and graphite fire seals - so the valve is suitable for wet sour hydrocarbon service. State the H2S partial pressure and the required hardness cap (commonly 22 HRC) in the enquiry, because sour-service discipline cannot be added after the steel is poured.

Do you supply the valve and actuator as one matched package with OEM options?

Yes. The trunnion ball valve and its actuator are sized together against your differential pressure and duty, delivered stroked, tested and documented as one package with a single point of responsibility. OEM labelling, painting and a chosen actuator brand are supported; send your datasheet and marking requirements with the enquiry.