III. Feature Description

A. Fixed Ball (Trunnion-Mounted) Design: Stability & Longevity

• Pressure Force Distribution: Fluid pressure acts on the ball, but trunnions (upper/lower) transfer these forces to robust bearings—preventing the ball from shifting into the seat. This eliminates seat deformation, a common issue in floating ball valves that causes increased torque and reduced seal life. In a DN200 Class 40 gas pipeline, this design maintains consistent sealing for 8–12 years, compared to 3–5 years for floating ball alternatives.
• Low Operational Torque: Reduced friction between the ball and seats (due to trunnion support) lowers torque requirements. A DN200 pneumatic model requires only 80 N·m of torque to operate—half the torque needed for a floating ball valve of the same size—enabling smaller, more energy-efficient actuators.
• High-Pressure Compatibility: The trunnion structure withstands Class 40–600 pressures without structural failure. In oil refinery feed lines (Class 300), the valve handles 10MPa pressure spikes without leakage, outperforming floating ball valves that risk seat damage under such conditions.

B. Hard-Seal Performance: Reliability in Harsh Media

• High-Temperature Tolerance: Stellite 6 retains its hardness (≥58 HRC) up to 425℃, making the valve suitable for steam auxiliary lines in power plants or heated gas lines in petrochemical facilities—applications where soft seals (PTFE) would degrade rapidly.
• Abrasive Media Resistance: The hard-faced sealing surface resists wear from particulate-laden media, such as natural gas with fine sand or industrial water with sediment. In a city gas distribution network, the valve operated reliably for 10 years, while a soft-sealed valve required quarterly seat replacements.
• Fire-Safe Compliance: In the event of a fire, the metal-to-metal hard seal maintains partial sealing capability (per API 607 standards), preventing catastrophic media release. This is critical for gas or oil facilities, where fires pose severe safety and environmental risks.

C. F304 Stainless Steel Construction: Corrosion Resistance

• Gas & Water Compatibility: The alloy’s chromium-nickel composition forms a passive oxide layer that resists corrosion from natural gas, propane, and chlorinated water. In a coastal city’s gas pipeline, F304 prevented rust formation from salt air, whereas carbon steel valves corroded within 2 years.
• Chemical Inertness: F304 is inert to most mild acids (e.g., acetic acid) and alkalis (e.g., sodium bicarbonate), making it suitable for chemical processing lines handling non-aggressive solvents. For more aggressive media (e.g., seawater), optional 316L stainless steel (with molybdenum) enhances chloride resistance.
• Hygienic Qualities: The smooth, non-porous surface of F304 is easy to clean and sanitize, meeting the needs of water treatment facilities or food-grade fluid applications (with optional electropolishing for Ra ≤0.8μm surface finish).

D. Pneumatic Actuation: Automation & Safety

• Rapid Response: Double-acting pneumatic actuators open/close the valve in 15–25 seconds for DN200, enabling quick process adjustments or emergency shutdowns. In a chemical plant’s batch reactor feed line, this speed prevents over-pressurization by stopping flow within seconds of a pressure spike.
• Fail-Safe Operation: Spring-return actuators provide critical safety in gas applications—if air supply fails, the spring auto-closes the valve, preventing uncontrolled gas release. This feature aligns with global gas safety standards (e.g., EN 14464 for city gas).
• Remote Control Compatibility: Pneumatic actuators integrate with SCADA/DCS systems via solenoid valves or positioners, enabling remote monitoring and control. For offshore gas platforms or remote pipeline stations, this eliminates the need for on-site operators, reducing labor costs and safety risks.

E. Flanged Connection: Secure Installation & Maintenance Ease

• Leak-Tight Sealing: Bolted flanges distribute clamping force evenly across the gasket, ensuring a secure seal even under pressure or temperature fluctuations. In a DN200 oil pipeline, this design prevented fugitive emissions of hydrocarbons, meeting EPA Methane Rule requirements.
• Simplified Installation & Retrofit: Flanges align with standard pipeline components, reducing installation time by 30% compared to welded valves. When upgrading an existing gas line, the valve can be installed without cutting the pipeline—minimizing downtime for utilities or industrial plants.
• Interchangeability: ASME B16.5 compliance ensures the valve works with flanges from other manufacturers, enhancing versatility in multi-vendor projects. This interchangeability reduces inventory costs for plant operators who can standardize on a single valve model.

IV. Manufacturing Processes

A. Material Inspection & Preparation

• F304 Stainless Steel Verification: Billets are tested via spectral analysis (XRF) to confirm chemical composition (Cr: 18–20%, Ni: 8–10.5%) and ultrasonic testing (UT) to detect internal defects (porosity, cracks). Mechanical testing (tensile strength ≥515MPa, yield strength ≥205MPa) ensures compliance with ASTM A351.
• Stellite 6 Validation: Hard-seal material is tested for hardness (≥58 HRC) via Rockwell testing and chemical composition (Co: 50–60%, Cr: 25–30%) to ensure wear resistance.
• Heat Treatment: F304 billets undergo solution annealing (1050℃, water-quenched) to dissolve carbide precipitates, preventing intergranular corrosion in service. This step is documented in Material Test Reports (MTRs) for traceability.

B. Valve Body & Ball Fabrication

• Body Manufacturing: F304 stainless steel bodies are produced via investment casting (for complex geometries like trunnion seats) or forging (for high-pressure Class 300+ models). Castings are cleaned via shot blasting and inspected via liquid penetrant testing (PT) to detect surface cracks.
• CNC Machining: Critical surfaces—including flange faces, trunnion bearings, and seat pockets—are machined using 5-axis CNC centers. Flange faces are machined to ASME B16.5 flatness (≤0.05mm/m) and surface finish (Ra ≤3.2μm) for proper gasket seating. The ball’s spherical surface is ground to Ra ≤0.2μm using a spherical grinder, ensuring uniform contact with the hard seal.
• Hard-Seal Application: Stellite 6 is applied to valve seats via plasma transfer arc (PTA) welding—a precise process that minimizes heat input and prevents distortion. The welded surface is then ground to match the ball’s curvature, with a final lapping step to achieve ANSI/FCI Class IV leakage performance.

C. Actuator Integration & Assembly

• Trunnion & Bearing Installation: Upper and lower trunnions are press-fitted into the valve body, with PTFE-impregnated bronze bearings to reduce friction. Bearings are lubricated with high-temperature grease (resistant to 200℃) for long-term smooth operation.
• Ball & Stem Assembly: The ground ball is inserted into the body, and the stem is connected via a drive key—ensuring torque transfer during operation. The stem packing (graphite-PTFE) is installed in layers, with controlled compression to balance sealing and torque requirements.
• Pneumatic Actuator Mounting: Actuators are mounted via an ISO 5211 adapter flange, with laser alignment to ensure coaxiality (stem runout ≤0.05mm)—preventing binding. Solenoid valves and limit switches are calibrated to trigger at fully open/closed positions, protecting seals from over-travel.

D. Quality Testing & Certification

• Hydrostatic Testing: Per API 598, the valve shell is tested at 1.5× rated pressure (9.6MPa for Class 40) for 30 minutes—no leakage, sweating, or deformation is allowed. Seat testing is performed at 1.1× rated pressure (7.04MPa), with leakage measured via bubble counting (≤1 bubble per minute for Class IV).
• Pneumatic Testing: For gas service, the valve is tested with nitrogen at 0.6MPa to confirm airtight sealing—critical for preventing gas leaks in hazardous environments.
• Operational Testing: The valve is cycled 100 times (open/close) to verify smooth operation, consistent torque, and actuator response. Manual override is tested to ensure functionality during emergencies.
• Non-Destructive Testing (NDT): Welds (e.g., Stellite 6 seat welds) undergo radiographic testing (RT) to detect internal defects; the valve body is inspected via magnetic particle testing (MPI) for surface cracks.

E. Final Inspection & Documentation

• Visual Inspection: The valve is checked for surface defects, proper marking (size, pressure rating, material, serial number), and compliance with ASME B16.34. Marking is permanent (laser-etched) for traceability.
• Documentation: Each valve includes an MTR for F304 stainless steel, hydrostatic/pneumatic test reports, and compliance certificates (API 608, ISO 9001). For hazardous area applications, ATEX/IECEx certificates are provided.