API 6D ANSI CLASS300 CE NACE MR0175 DN300 CF8/CF8M Stainless Steel 2PC Flanged Trunnion Mounted Ball Valve by TIANYU
I. Product Overview & Core Specifications
The TIANYU API 6D trunnion mounted ball valve is a precision-engineered fluid control solution purpose-built for the most demanding oil and gas, petrochemical, and industrial pipeline applications, with a nominal diameter of DN300 and pressure rating of ANSI CLASS300 delivering robust performance for medium-to-large flow rate systems requiring uncompromising isolation and shutoff reliability. As a 2-piece (2PC) flanged configuration, this valve adheres to the strictest global industry standards, integrating sour service compliance with premium corrosion-resistant materials to ensure long-term operational integrity in harsh and corrosive operating environments.
Constructed from CF8 (AISI 304) and CF8M (AISI 316) stainless steel for all pressure-containing components, including the body, bonnet, and ball, the valve offers exceptional resistance to general corrosion, pitting, crevice corrosion, and oxidation—critical properties for contact with crude oil, natural gas, sour gas, produced water, steam, and mild to moderate chemical process fluids. CF8 stainless steel delivers superior corrosion protection in neutral and mild acidic environments, while CF8M incorporates molybdenum to enhance resistance to pitting and crevice corrosion in chloride-rich and sour service conditions, aligning with NACE MR0175/ISO 15156 standards for sour gas handling.
Rated for ANSI CLASS300, the valve operates reliably at a maximum working pressure of 5.17 MPa (750 PSI) and a broad temperature range of -29°C to 204°C as standard, with optional extended temperature ratings available for extreme low or high-temperature applications. The trunnion mounted ball design, a defining feature of this valve, supports the spherical ball on precision-machined upper and lower trunnions, eliminating the risk of ball displacement under high line pressure—a common limitation of floating ball valves. This design distributes hydraulic forces evenly across the trunnion bearings and seat assemblies, ensuring consistent sealing performance regardless of pressure fluctuations and extending the service life of internal components by minimizing friction and wear.
Equipped with flanged end connections compliant with ANSI B16.5, the valve enables seamless, leak-proof integration into standard industrial pipeline systems, with standardized flange dimensions, bolt patterns, and face finishes (RF – Raised Face as standard) ensuring interoperability with existing infrastructure and reducing installation time and costs. The 2-piece body construction features a bolted bonnet-to-body joint with a premium spiral wound gasket (flexible graphite with 316SS inner ring) for a secure, fire-safe seal, facilitating easy disassembly for maintenance, inspection, and replacement of internal components without removing the entire valve from the pipeline— a key advantage for critical process systems where downtime must be minimized.
The valve incorporates a soft-seated or metal-seated design (soft-seated as standard) to meet diverse leakage requirements, with soft seats engineered for bubble-tight shutoff compliant with ANSI/FCI Class VI and metal seats for high-temperature, high-pressure, and abrasive fluid applications compliant with ANSI/FCI Class IV. The stem assembly features an anti-blowout design, a critical safety feature that mechanically retains the stem within the body to prevent ejection under high pressure, and a multi-layer packing system (PTFE with graphite backup rings) to eliminate fugitive emissions, meeting the strict low-emission requirements of ISO 15848-1 and EPA Method 21. Actuation options include manual gear operation (standard for DN300 CLASS300), pneumatic, electric, or hydraulic actuation, all integrated with a visual position indicator and optional limit switches, solenoid valves, and positioners for remote monitoring and control.
II. Design Features & Functional Advantages
The TIANYU API 6D DN300 CLASS300 trunnion mounted ball valve is engineered with a suite of innovative design features that elevate its performance, safety, and operational efficiency beyond conventional ball valves, addressing the unique challenges of oil and gas transmission, petrochemical processing, and industrial fluid control—including sour service, high pressure, and extended service intervals.
At the core of its design excellence is the trunnion mounted ball configuration, which redefines sealing reliability in high-pressure applications. Unlike floating ball valves, which rely on fluid pressure to seat the ball against the downstream seat, the trunnion mounted design uses pre-loaded seat springs to maintain constant contact between the ball and both upstream and downstream seats, ensuring a positive seal in both open and closed positions, even at low line pressures or during pressure transients. This bi-directional sealing capability eliminates the risk of leakage caused by pressure imbalances, making the valve ideal for bi-directional flow systems and isolation applications where absolute shutoff is non-negotiable. The precision-machined trunnions are fitted with anti-friction bearings, reducing operating torque and enabling smooth, effortless actuation—even for the large DN300 size—while minimizing wear on the trunnion and body bore surfaces.
The valve’s 2-piece bolted body construction strikes the perfect balance between structural integrity and maintainability. The one-piece body and bonnet (2PC design) eliminates the need for a mid-body joint, reducing potential leak points and enhancing the valve’s structural strength for high-pressure CLASS300 service. The bolted bonnet connection allows for easy removal of the bonnet and internal trim (ball, seats, stem) without disconnecting the valve body from the pipeline, enabling rapid maintenance and inspection. The bonnet joint features a fire-safe spiral wound gasket and a live-loaded packing system, ensuring the seal remains intact even under thermal expansion or contraction and meeting fire-safe design requirements of API 607 and API 6FA.
Sour service compliance is a cornerstone of the valve’s design, with all wetted components manufactured from CF8/CF8M stainless steel that meets NACE MR0175/ISO 15156 standards for resistance to sulfide stress cracking (SSC) and hydrogen induced cracking (HIC). The material selection is complemented by a precision machining process that eliminates sharp edges, notches, and surface defects—common initiators of SSC in sour service—and a post-machining passivation treatment to restore the stainless steel’s passive oxide layer, enhancing corrosion resistance and ensuring compliance with NACE’s strict material and manufacturing requirements.
The valve’s sealing system is engineered for versatility and reliability, with standard soft seats made from PEEK (Polyether Ether Ketone) or reinforced PTFE (Polytetrafluoroethylene) for bubble-tight shutoff. PEEK seats offer exceptional thermal stability (up to 260°C), chemical resistance, and wear resistance, making them ideal for most oil and gas and petrochemical applications, while reinforced PTFE seats provide superior low-temperature performance (down to -50°C). For high-temperature, high-pressure, or abrasive fluid applications, metal seats (Stellite 6 overlay on 316SS) are available, delivering a metal-to-metal seal that maintains integrity at temperatures up to 427°C and resists wear from particulate-laden fluids. All seat assemblies are spring-loaded, compensating for thermal expansion, contraction, and wear over time to ensure a consistent seal throughout the valve’s service life.
Safety and environmental protection are integrated into every design detail, starting with the anti-blowout stem. The stem is machined with a circumferential groove that engages with a retaining ring in the body bore, preventing the stem from being ejected from the body even if the primary packing seal fails under high pressure—eliminating a major safety hazard in industrial pipeline systems. The multi-layer stem packing system features PTFE V-rings with graphite backup rings, providing a low-friction seal that eliminates fugitive emissions and meets ISO 15848-1 (TA-Luft) and EPA Method 21 requirements for low-emission valves. The packing gland is live-loaded with Belleville washers, maintaining constant packing compression even as the packing settles or wears, ensuring long-term emission control without the need for frequent re-tightening.
The valve is also engineered with a fire-safe design compliant with API 607 (7th edition) and API 6FA, a critical requirement for oil and gas and petrochemical applications where fire risk is inherent. In the event of a fire, the soft seat material may degrade, but the valve’s metal-to-metal backup seal (between the ball and metal seat retainers, and the bonnet and body joint) activates to maintain a pressure-tight seal, preventing the release of flammable fluids and minimizing fire propagation. The fire-safe design is validated through rigorous third-party testing, ensuring the valve meets the strict performance criteria of API and ANSI fire-safe standards.
For operational convenience, the valve is fitted with a robust manual gear operator as standard for DN300 CLASS300, featuring a heavy-duty gear box with precision-machined gears that reduce operating torque by up to 80%, enabling a single operator to actuate the large valve with minimal effort. The gear operator includes a positive-locking handwheel to prevent accidental operation, a visual position indicator (open/closed) with clear markings, and a grease fitting for easy lubrication of the gear train and trunnion bearings. Optional actuation systems (pneumatic rack and pinion, electric quarter-turn, hydraulic) are fully integrated with the valve’s stem and position indicator, with mounting flanges compliant with ISO 5211 for seamless compatibility with industry-standard actuation equipment. The valve also features optional accessories such as limit switches, solenoid valves, positioners, and pressure gauges, enabling integration with SCADA, DCS, and PLC systems for remote monitoring, control, and automation.
