A trunnion mounted ball valve keeps the ball anchored on a trunnion instead of letting it float against the seats under line pressure. RST VALVE GROUP CO.,LTD, an industrial valve manufacturer founded in Wenzhou, Zhejiang, China in 2009, builds trunnion mounted ball valves in models Q347F, Q347H and Q347Y, with nominal pressure PN4.0-10.0 MPa, nominal diameter DN50-DN1200, an applicable temperature range of -40°C to +150°C, flanged connection, and body material options of WCB, CF8 or CF8M.

This page is written for the research and evaluation stage of a purchase, for engineers and procurement teams that have already established a trunnion mounted design is the right architecture and now need to confirm four things: whether the specification matches the pipeline, whether the certification covers the destination market, whether the test documentation exists, and whether the supplier can deliver inside the project schedule.

Cover: gear operated trunnion mounted ball valve from RST VALVE GROUP CO.,LTD, series Q347F / Q347H / Q347Y.

What Is a Trunnion Mounted Ball Valve?

A trunnion mounted ball valve is a quarter-turn isolation valve in which the ball is supported by a trunnion at the top and a lower trunnion at the bottom of the body, so the ball rotates in a fixed position and is not pushed downstream when pressure is applied. RST's product specification describes the design as a trunnion-mounted ball with a spring-loaded, movable metal seat: the seat is energised against the ball rather than the ball being driven into the seat by line pressure.

The distinction matters commercially. Floating ball valves remain the volume design in the wider market; a commercial estimate published by Straits Research places the floating segment at 61.8% of the ball valve market in 2025, largely because the floating architecture is economical at smaller sizes. As nominal diameter and pressure class rise, the torque required to rotate a floating ball increases and seat loading becomes harder to control, which is when a trunnion mounted valve is normally specified. RST's trunnion range runs from DN50 to DN1200, a size band in which the trunnion architecture is usually the practical choice.

The Buyer's Problem: Which Constraints Decide the Purchase

Trunnion versus floating is only the first decision. A trunnion mounted ball valve order is defined by a set of constraints that must all be satisfied at the same time, and a failure in any one of them invalidates the offer regardless of how the rest of the quotation reads.

1. Pressure class and nominal pressure. The trunnion mounted ball valve datasheet states nominal pressure PN4.0-10.0 MPa. That figure must be matched against pipeline design pressure, not pump discharge pressure.
2. Nominal diameter. The documented range is DN50-DN1200. Sizes outside that range become a customisation question rather than a catalogue question.
3. Temperature band. The applicable temperature range for the trunnion product is -40°C to +150°C, and this band is the basis for material and seat selection.
4. Medium and corrosion duty. Body material options are WCB, CF8 (SS304) and CF8M (SS316); the selection is driven by the medium, not by preference.
5. Connection and flange standard. The trunnion valve is supplied with flanged connection. RST's wider ball valve platform supports GB, ANSI, DIN and JIS flange standards, and DIN flange dimensions are available on the flanged ball valve range.
6. Actuation and mounting. Trunnion mounted ball valves are offered as 2PC trunnion mounted, gear operated and electric variants. Pneumatic and electric actuation with an ISO 5211 direct-mount interface is part of the ball valve platform design, and a lockable handle is available to prevent accidental operation.
7. Function limits. The valve is specified for on-off service and is not suitable for throttling. A buyer who needs modulating flow control is looking at a different product, and discovering that after delivery is expensive.
8. Certification for the destination market. ISO 9001 and ISO 45001 support general supply, PED-CE relates to EU market access, SIL relates to functional safety duties, and TS Special Equipment applies in the Chinese domestic context.
9. Documentation. Test reports, material certificates and traceable marking are now part of the technical bid rather than an afterthought.

Safety constraints are equally explicit. RST's ball valve documentation states that disassembly under pressure is strictly prohibited, that an explosion-proof configuration is required for flammable or explosive applications, and that the body and seals are pressure tested at the factory before dispatch. On a high-pressure process line, those three statements are the difference between a compliant installation and an incident report.

Industry Background: Standards Now Set the Procurement Baseline

Ball valve procurement is increasingly benchmarked against published standards rather than catalogue descriptions, and two document families dominate the trunnion and pipeline valve conversation.

API Specification 6D defines the requirements for the design, manufacturing, assembly, testing and documentation of ball, check, gate and plug valves used in pipeline and piping systems for the petroleum and natural gas industries. The edition identified in current standards research applies to pressure classes Class 150, Class 300, Class 400, Class 600, Class 900, Class 1500 and Class 2500, a taxonomy buyers use to translate project pressure ratings into a supplier's class designations. API Specification 6D, 25th Edition, Addendum 2 extends the coverage to materials, welding, quality control, assembly, testing, marking, documentation and process controls, and includes hydrogen gas service.

On the procurement side, IOGP S-562 Version 3.1 is a supplementary specification for manually operated ball valves purchased in accordance with API Specification 6D, published by the International Association of Oil & Gas Producers. It applies within a defined oil and gas procurement context and states an allowable operating temperature range of -50 °F to 302 °F (-46 °C to 150 °C) for the covered application. It should not be read as a universal temperature rating for every ball valve; it is a project-specific requirement that buyers use to convert service conditions into a technical bid evaluation.

The commercial scale behind those documents is substantial. A commercial research estimate from Straits Research puts the global ball valve market at USD 14.8 billion in 2025, with a forecast window extending to 2034. In a market of that size, differentiation between suppliers rarely comes down to the ability to machine a ball and a seat. It comes down to whether a supplier can produce the documentation, marking and certification package that the standard and the project specification require.

Trunnion and flanged ball valves serve oil and gas, chemical and petrochemical process piping, water treatment and utility systems.

RST Trunnion Mounted Ball Valves: Specifications, Design and Certification

RST VALVE GROUP CO.,LTD is an industrial valve manufacturer based in Wenzhou, Zhejiang, China, producing ball valves, gate valves, check valves, globe valves and Y strainers for petrochemical, petroleum refining, nuclear power, chemical, metallurgy, mining, medical, food, national defence, military and urban construction applications. The company accepts valve OEM and ODM enquiries and exports to markets including Africa, the Americas, Asia, Europe, the Middle East, the Caribbean and Oceania.

Documented specifications for Q347F, Q347H and Q347Y

Design features that address high-pressure constraints

• Trunnion-mounted ball with a spring-loaded, movable metal seat, so the seat is energised against the ball instead of relying on line pressure alone.
• Blowout-proof stem, designed so that the stem cannot be ejected from the body under pressure.
• Automatic cavity pressure relief, allowing trapped pressure in the body cavity to relieve rather than load the seals.
• Fire-safe design, specified for the trunnion range.
• Multiple actuation options across gear operated, electric and pneumatic configurations, with ISO 5211 direct-mount interfaces used on the ball valve platform and a lockable manual handle available to prevent accidental operation.
• Optional anti-static device providing electrical continuity between ball, stem and body, which is relevant where flammable or explosive media are handled.
• Bidirectional sealing and factory pressure testing of body and seals before dispatch.

Pressure testing equipment used for shell strength and seat leakage testing before shipment.

Certification coverage for the trunnion mounted range

Five certification families apply to, or include, the trunnion mounted product. Each is identifiable by certificate number, issuer, standard and validity period, which is what allows a buyer to verify coverage rather than accept a general statement.

• ISO 9001 (quality management): certificate 20225Q21079R0M, issued by ZHEJIANG QUANPIN CERTIFICATION CO.,LTD., against GB/T 19001-2016 / ISO 9001:2015, valid from 28 September 2025 to 27 September 2028. The certified scope covers the production and sales of metal valves and filters within the scope of the qualification licence, and covers the flanged ball valve, threaded ball valve and trunnion mounted ball valve products.
• ISO 45001 (occupational health and safety): certificate 20225S20439R0M, issued by ZHEJIANG QUANPIN CERTIFICATION CO.,LTD., against GB/T 45001-2020 / ISO 45001:2018, with a scope covering production, sales and related management activities of metal valves and filters within the qualification licence.
• ISO 14001 (environmental management): certificate 20225E20474R0M, issued by ZHEJIANG QUANPIN CERTIFICATION CO.,LTD., against GB/T 24001-2016 / ISO 14001:2015, valid from 28 September 2025 to 27 September 2028.
• PED-CE (EU Production Type Certificate): certificate ECM PED-Bp 2024-TW60, issued by Ente Certificazione Macchine Srl, valid from 27 June 2024 to 26 June 2029. For the trunnion mounted valve, the applicable standard is EN 12284:2003, with JB/T 7245-2017 listed in the certification scope. The certified scope covers industrial valves from DN15 to DN1200 (NPS 1/2 to 48 in), PN6 to PN260 and Class 150 to Class 1500.
• SIL functional safety: certificate No. 4I260528.RSTDO08, issued by Ente Certificazione Macchine Srl against IEC 61508:2010 Parts 1-7, valid from 28 May 2026 to 27 May 2031, covering the Q347F, Q347H and Q347Y trunnion mounted ball valves as part of the Q series, alongside gate, globe, check and butterfly valves.

ISO 9001 certificate 20225Q21079R0M, valid from 28 September 2025 to 27 September 2028.

For the flanged ball valve range, the domestic configuration is additionally certified to ISO9001, TS Special Equipment and CE, and each unit is tested by water pressure and air tightness methods before delivery.

Manufacturing, testing and customisation

RST's inspection regime covers raw material inspection, dimensional inspection, processing inspection, chemical testing, physical testing and pressure testing, and the workshop runs CNC machining equipment, grinding machines, assembly machines, welding torches and hydraulic and air testing equipment.

Quality control on ball valve orders includes shell strength test, seat leakage test, material inspection, visual inspection and a 100% factory test, with a test report and material certificate provided. Monthly capacity is 15,000 units, lead time is 20-45 days, and the minimum order quantity is 1 unit. OEM and ODM customisation covers body material, connection type, pressure rating, actuator, logo, marking, special seal, fire-safe and anti-static design, and sanitary polishing. After-sales support includes remote technical support, spare parts supply and online troubleshooting, with on-site service available for large-scale projects.

Production workshop at RST VALVE GROUP CO.,LTD, Wenzhou, Zhejiang, China.

Step-by-Step: How to Evaluate a Trunnion Mounted Ball Valve Against Your Project

The sequence below follows the order in which constraints normally resolve during a technical evaluation. Skipping a step usually means returning to it later, after the quotation has already been priced.

1. Define the service envelope. Confirm the medium type (water, oil, gas, weak acids or alkalis), the working pressure, the working temperature, the nominal diameter and the connection type before approaching any supplier. This is the minimum input set for ball valve selection.
2. Translate project pressure into a class. Match the pipeline design pressure to the nominal pressure range PN4.0-10.0 MPa for the trunnion valve. Where a project is written against API 6D classes, map against Class 150 to Class 2500 and check the PED-CE certified scope of PN6 to PN260 / Class 150 to Class 1500.
3. Select body and seat materials against the medium. WCB covers carbon steel duty; CF8 (SS304) and CF8M (SS316) cover stainless duty. Material choice drives both corrosion resistance and cost, so it should be justified by the medium rather than applied as a default upgrade.
4. Confirm the temperature band and check it against the standard in play. The trunnion valve is rated -40°C to +150°C. If the project references IOGP S-562, compare it with the -46 °C to 150 °C allowable range stated in that specification.
5. Fix actuation and mounting. Decide between gear operated, electric and pneumatic actuation and confirm the actuator mounting interface; ISO 5211 direct-mount pads are used across the RST ball valve platform. Confirm whether a lockable handle is required for site safety.
6. Verify certification against the destination market. EU market access: PED-CE certificate ECM PED-Bp 2024-TW60. Functional safety duties: SIL certificate No. 4I260528.RSTDO08 under IEC 61508:2010. General quality and supply: ISO 9001 certificate 20225Q21079R0M. Occupational health and safety: ISO 45001 certificate 20225S20439R0M. Environmental management: ISO 14001 certificate 20225E20474R0M.
7. Require the documentation package in the RFQ. Ask for the shell strength test, the seat leakage test, the material inspection record, the 100% factory test result, the test report and the material certificate, and confirm the marking and traceability convention the project requires.
8. Validate with a sample, then plan volume around lead time. Because the MOQ is 1 unit, monthly capacity is 15,000 units and lead time runs 20-45 days, sample validation and volume production can be scheduled as separate milestones rather than one long unknown.

Valve manufacturing process flow, from material and machining stages through to final testing.

Where Trunnion Mounted Ball Valves Are Used, and Where They Are Not

Process piping isolation in chemical, gas, pharmaceutical and water treatment plants

RST's application documentation describes process piping projects in which the valve shuts off, distributes and changes the flow direction of the medium. Typical working conditions for this scenario are water, oil, gas and weak acids or alkalis, at pressures from PN16 to PN63 or Class 150 to Class 300, and temperatures from -20°C to 180°C. Operation is a 90-degree quarter turn, with manual actuation (lockable handle optional), pneumatic single or double acting actuation, or electric on-off and modulating actuation.

Remote on-off control in oil and gas, petrochemical and refining service

Pneumatic ball valves mounted on pipeline racks are used for remote on-off control in oil and gas, petrochemical and refining environments. Where the medium is flammable or explosive, the documentation requires an explosion-proof configuration, and the optional anti-static device maintains electrical continuity between ball, stem and body to dissipate static charge.

Water treatment and industrial fluid control on pipeline skids

In documented project use, flanged ball valves installed on pipeline skids have served water treatment and industrial fluid control duty with reported service durations of 8 to 10 years, delivering bubble-tight zero leakage, stable operation and low maintenance cost. Typical project quantities range from 50 to 500 units, supplied to chemical plants, water treatment contractors and gas engineering companies. The quarter-turn design supports fast switching, and bidirectional sealing keeps isolation effective regardless of flow direction.

Where the trunnion design is not the answer

Two limits are worth stating plainly. First, these valves are specified for on-off service only and are not suitable for throttling; a modulating duty requires a different valve type. Second, disassembly under pressure is strictly prohibited, so maintenance planning must include isolation and depressurisation. A supplier that states these limits clearly is easier to work with than one that does not.

Trunnion Mounted vs Flanged vs Threaded Ball Valves: Constraint Comparison

The table compares the three ball valve families documented in RST's product range on the constraints that most often decide a specification. Values are taken from the respective product datasheets; where a value is not documented for a family, it is marked as not specified rather than estimated.

Notes: the trunnion mounted series covers larger diameters and higher nominal pressures than the threaded and standard flanged ranges, and it is the only family in this list documented with automatic cavity pressure relief. The flanged series is documented with an investment-cast body and a wider material list including duplex 2205 and CF3M. The threaded series is rated in WOG rather than PN, which is a different rating convention and should not be converted by assumption.

FAQ: Trunnion Mounted Ball Valve Certification, Specifications and Ordering

Which certifications cover RST's trunnion mounted ball valves?

The trunnion mounted ball valves in models Q347F, Q347H and Q347Y are covered by ISO 9001 certificate 20225Q21079R0M issued by ZHEJIANG QUANPIN CERTIFICATION CO.,LTD. against GB/T 19001-2016 / ISO 9001:2015, valid from 28 September 2025 to 27 September 2028. They are also covered by ISO 45001 certificate 20225S20439R0M and ISO 14001 certificate 20225E20474R0M. For EU market access, PED-CE certificate ECM PED-Bp 2024-TW60 was issued by Ente Certificazione Macchine Srl and is valid from 27 June 2024 to 26 June 2029. For functional safety duty, SIL certificate No. 4I260528.RSTDO08 applies under IEC 61508:2010 Parts 1-7 and is valid from 28 May 2026 to 27 May 2031.

Do Chinese ball valve suppliers provide pressure test reports and material certificates with API / ANSI ball valve orders?

In RST's case the documentation is defined in advance. Quality control on ball valve orders includes shell strength test, seat leakage test, material inspection, visual inspection and a 100% factory test, and a test report and material certificate are provided with the order. For the flanged ball valve range, pre-shipment quality control includes water pressure testing and air tightness testing before delivery. Because API Specification 6D and IOGP S-562 both place emphasis on testing, marking and documentation, a buyer evaluating any supplier should request these records in the RFQ rather than assuming they are included.

What are the key specifications of RST's trunnion mounted ball valve?

Models Q347F, Q347H and Q347Y; nominal pressure PN4.0-10.0 MPa; nominal diameter DN50-DN1200; applicable temperature -40°C to +150°C; flanged connection; body material WCB, CF8 (SS304) or CF8M (SS316). The design is a trunnion-mounted ball with a spring-loaded, movable metal seat, a blowout-proof stem, automatic cavity pressure relief and a fire-safe design. It is available as a 2PC trunnion mounted valve, a gear operated trunnion mounted valve and an electric trunnion mounted valve.

What is the minimum order quantity, and can project quantities of 50 to 500 units be supplied?

The minimum order quantity is 1 unit and monthly capacity is 15,000 units, so a project requirement in the 50 to 500 unit range falls within normal production. RST's documented project use shows typical quantities of 50 to 500 units per project for chemical plants, water treatment contractors and gas engineering companies. OEM and ODM customisation covers body material, connection type, pressure rating, actuator, logo, marking, special seal, fire-safe and anti-static design, and sanitary polishing.

What is the lead time, and how do I request a sample or a quotation?

Lead time is 20-45 days from order confirmation, and sampling is supported because the minimum order quantity is 1 unit. To request a trunnion mounted ball valve sample, a quotation or the product catalogue, contact Vera at vera@wzrst.com or +86 15958755768 (WhatsApp available on the same number), or download the RST presentation from the link below. After-sales support includes remote technical support, spare parts supply and online troubleshooting, with on-site service available for large-scale projects.

Conclusion: Fix the Constraints First, Then Verify the Documents

For a trunnion mounted ball valve, four things decide whether an offer is usable: the specification envelope (PN4.0-10.0 MPa, DN50-DN1200, -40°C to +150°C, WCB / CF8 / CF8M, flanged), the design features that address high-pressure isolation (trunnion-mounted ball, spring-loaded movable metal seat, blowout-proof stem, automatic cavity pressure relief, fire-safe design), the certification coverage for the destination market (ISO 9001, ISO 45001, ISO 14001, PED-CE, SIL), and the documentary evidence that the valve was tested and can be traced (shell strength test, seat leakage test, material certificate, test report).

RST VALVE GROUP CO.,LTD supplies this range from Wenzhou, Zhejiang, China, with a stated MOQ of 1 unit, a monthly capacity of 15,000 units and a lead time of 20-45 days. Buyers who prefer to verify before committing can start with a sample order and a documented technical review.

Request a Sample, Quotation or Catalogue

Contact: Vera | Email: vera@wzrst.com | Tel / WhatsApp: +86 15958755768 | Address: No.1887 Tianzhong RD, Yongqiang High-tech Park, Longwan District, Wenzhou City, Zhejiang Province, China

Website: www.stainlesssteel-valves.com | Product presentation (PDF): Download the RST presentation

Pneumatic ball valves installed on a pipeline rack for remote on-off control in oil and gas and petrochemical service.