Trunnion Ball Valve (Instrumentation, 1/16"–1")

A trunnion ball valve is a quarter-turn ball valve in which the ball is fixed and supported by integral top and bottom trunnions (stub shafts), so line pressure is carried by the trunnion bearings rather than pressing the ball into the downstream seat, giving lower, more constant operating torque and reduced seat wear than a floating design. Crestflo builds the instrumentation trunnion ball valve in 1/16" to 1" sizes, in stainless steel and corrosion-resistant alloys, with tube-fitting or threaded ends. This is a small-bore instrument-isolation valve for tubing, gauge and sensing lines, not a large-bore pipeline or API 6D transmission ball valve, and not a plumbing ball valve.

Reviewed by the Crestflo Engineering Team

Crestflo is the instrumentation division of a four-decade-old, Government-of-India-recognized export house with a proven Middle-East delivery record. We manufacture trunnion-mounted ball valves for US drop-in service and support end users, distributors, OEMs and equipment builders. Ready stock for standard items, made-to-order for specials, 6–8 week delivery. Request a quote.

Also Known As: Trunnion-Mounted, Fixed-Ball & Trunnion-Supported Ball Valve

Buyers and specifiers refer to this valve by several names depending on the drawing convention and service. Common designations include trunnion-mounted ball valve, trunnion mounted ball valve, trunnion valve, fixed-ball ball valve, trunnion-supported ball valve, and, for small-bore work, the instrumentation trunnion ball valve or high-pressure trunnion ball valve. It is specified as a config of the instrumentation ball valve, contrasted with the floating-ball design covered on that page. Switching variants such as the three-way, L-port and T-port ball valves are covered on their own pages.

What Is a Trunnion Ball Valve and How Does It Work?

The working principle of a trunnion ball valve is straightforward: it is a fixed-ball, low-torque quarter-turn isolation valve. Two integral trunnions, stub shafts at the top and bottom of the ball, hold the ball on a fixed axis so it cannot move downstream under pressure. Spring-energized seats are pushed against the ball to form the seal, and the trunnion bearings, not the seats, carry the pressure-induced side load. A quarter turn of the handle rotates the fixed ball between fully open (bore aligned with the flow path) and fully closed. Because the seats are energized by springs rather than by line pressure driving the ball, operating torque stays low and nearly constant across the pressure range, and seat wear is reduced, which is why the trunnion arrangement is favored for higher-pressure and high-cycle instrument service.

Trunnion vs Floating Ball Valve: How the Fixed-Ball Design Differs

The purpose of the trunnion is to fix the ball and carry its pressure load. In a floating ball valve the ball is free to shift downstream under pressure, energizing the downstream seat, so operating torque rises as pressure rises. In a trunnion (fixed-ball) valve the ball is anchored by the trunnions and spring-loaded seats do the sealing, so torque stays low and seat loading is controlled. The comparison below describes the general operating principle; select the arrangement to match your pressure, bore and cycle requirement.

For the floating-ball isolation valve, see the instrumentation ball valve page.

When to Choose a Trunnion (Fixed-Ball) Ball Valve

Choose a trunnion ball valve when the service demands low or predictable operating torque at higher pressure. It earns its place in high-pressure instrument hookups, in high-cycle duty where seat wear matters, and on actuated valves where a torque-limited pneumatic actuator benefits from the low, constant torque of a fixed ball. Many small-bore instrument valves are floating designs and serve well; the trunnion arrangement is the right selection when pressure, bore size for the class, or cycle life would make a floating ball's rising torque and seat load unacceptable.

Trunnion Ball Valve Sizes (1/16"–1") & End Connections: NPT, Tube-Fitting & Weld

Crestflo trunnion ball valves are made in nominal sizes from 1/16" to 1", in both imperial and metric, with a full range of instrument end connections. Tube-fitting (compression) ends are available in single- and double-ferrule form, with hardened or non-hardened ferrules to requirement. Threaded ends are cut to NPT per ASME B1.20.1; socket-weld and tube butt-weld ends are also offered. BSP (BSPT/BSPP) and DIN 2353 bite-type ends are supplied to requirement. Dimensions follow the applicable end-connection standard and are customizable to requirement.

High-Pressure Trunnion Ball Valve Ratings & Cold Working Pressure

The pressure rating of a trunnion ball valve is stated as a cold working pressure (CWP) and depends on body size, seat material and alloy. Small-bore instrument ball valves are commonly rated up to 6,000 psi (413 bar) CWP for isolation service, with 3,000 psi designs typical for general duty; values are per the applicable standard and customizable to requirement. Pressure-temperature ratings follow ASME B16.34 for the valve body, and seat and shell testing follows API 598. Certified per-model pressure-temperature curves are supplied with the quotation. Datasheets and CAD are available to customers on request.

Trunnion Ball Valve Seats, Seals & Temperature Limits: PTFE, RPTFE, PEEK & Metal Seat

The seat material sets the temperature and media limits of the valve. Standard published service limits for common instrument seat and seal materials are shown below; select the seat for your temperature and media, values per applicable standard and customizable to requirement.

For fire-safe and high-temperature isolation, a metal-seated (metal-to-metal) seat is available in place of the polymer seats, built to the API 607 fire-test basis where specified. The stem uses an anti-blowout, anti-static design with PTFE or graphite packing, and fugitive-emission control per ISO 15848 where specified. Flow coefficient (Cv) varies with size and bore/orifice size; the value for a given model is provided with the quotation.

Trunnion Ball Valve Materials: 316 Stainless, Duplex, 6-Moly, Monel, Inconel & Hastelloy

Crestflo trunnion ball valves are machined from bar stock and forgings in stainless steel and corrosion-resistant alloys, no brass is offered on this US instrumentation range. Standard bodies are 316/316L stainless and 304/304L; higher-alloy options cover chloride, sour and high-temperature service. Each grade links to its material page, and the same valve is available as a matrix build such as a Hastelloy C-276 instrumentation valve or an Inconel 625 instrumentation valve.

For sour service, alloys are supplied compliant with NACE MR0175 / ISO 15156. Full alloy options are on the materials hub.

Trunnion Ball Valve Configurations & Actuation: Full-Port, Fire-Safe & Pneumatic

Standard actuation is a manual lever or oval handle; a locking handle and panel-mount handle are available for panel and enclosure builds. The trunnion ball is supplied full-port or reduced-port, in bi-directional, high-cycle, zero-leak, two-piece and three-piece bolted-body, forged-body and bar-stock configurations. Pneumatic-actuated trunnion ball valves are offered for automated isolation, driven by a rack-and-pinion or scotch-yoke actuator, actuator sizing benefits directly from the low, constant torque of the fixed-ball design. Fire-safe designs are built to the API 607 test basis where specified. Finishes include electropolish, passivation and silver anti-galling plating, with oxygen-clean / UHP cleaning available on request per the applicable standard for oxygen and ultra-high-purity service, customizable to requirement.

Trunnion Ball Valve Standards, Certifications & Testing

Crestflo trunnion ball valves qualify to the standard approvals applicable to instrument valves: pressure-temperature ratings to ASME B16.34, seat and shell testing to API 598, fire-safe testing to API 607 where specified, fugitive-emission control per ISO 15848, and sour-service compliance to NACE MR0175 / ISO 15156. NPT ends are cut per ASME B1.20.1. Crestflo is ISO 9001 / 14001 / 45001 and PED certified. Every part is marked with its heat or lot number, and material is supplied with an EN 10204 MTC 3.1 certificate (3.2 on request). Testing includes hydraulic proof, burst and impulse, pneumatic, seat and shell leak, thermal cycling and positive material identification (PMI); in-house NDT plus destructive testing at ISO/IEC 17025-accredited labs, with third-party inspection on request. Certificates are held in our traceability records.

Trunnion Ball Valve Applications: Oil & Gas, Offshore, Hydrogen & Sampling

Instrument trunnion ball valves isolate high-pressure impulse, tubing and sensing lines across oil and gas (including sour service), petrochemical, offshore and subsea, hydrogen, LNG and cryogenic service, and analytical and sampling systems. Alloy and seat selection is matched to the media, temperature and pressure of each service, and the fixed-ball design suits high-cycle and actuated isolation on high-pressure instrument hookups.

Drop-In Interchange for Swagelok, Parker & Hoke Ball Valves

Crestflo trunnion ball valves are engineered as dimensional drop-in interchanges, a drop-in alternative to major instrument brands, so they fit existing tube-fitting envelopes and panel layouts. Rather than publish a fixed part-number table, our engineering team builds the interchange to your specification. Request your Swagelok or Parker A-Lok cross-reference, or see the full cross-reference program including Hoke. Swagelok®, Parker® and Hoke® are trademarks of their respective owners; Crestflo is not affiliated with or endorsed by them.

Why Crestflo for Trunnion Ball Valves

As a US-serving trunnion ball valve manufacturer and supplier, Crestflo delivers fixed-ball instrument valves in stainless steel and exotic alloys with a 6–8 week lead time against the 20-plus weeks typical of the majors, backed by the heritage of a four-decade Government-of-India-recognized export house. Ready stock for standard items, made-to-order for specials. Standard product is of Indian origin; US or European melt is available on request with full material traceability, see our US origin and compliance page. Small MOQ and private-label programs, MTC 3.1 with heat-number traceability, and ISO / NACE conformance are standard. Trunnion ball valve pricing is quoted per configuration, request a quote for your size, alloy and end connection. We Engineer Confidence.

For US inquiries, contact sales@crestflousa.com or +1 346 594 9005 (Houston, TX). Request a quote, request a sample, download the catalog, or talk to an engineer. Distributors can review the distributor program and OEMs the OEM program.

Frequently Asked Questions

Related Products & Resources

• Instrumentation valves, the full valve range
• Instrumentation ball valve, the floating-ball isolation valve
• Three-way, L-port and T-port ball valves
• CWP ball valve rating explainer and double block and bleed valve
• ASME B16.34 and NACE MR0175 standards
• Materials hub and instrumentation valve cross-reference