III. Feature Description

A. Trunnion-Mounted Ball Design: Stability Under Extreme Pressure

• Pressure Load Distribution: The ball is secured by upper and lower trunnions, which absorb the thrust generated by media pressure—transferring loads to the valve body rather than the seats. This eliminates seat deformation and uneven wear, even under PN64 high pressure, ensuring consistent sealing performance over 100,000+ cycles.
• Low Operational Torque: Trunnion supports and self-lubricating bearings reduce friction between the ball and seats, lowering operational torque by 30–50% compared to floating ball valves of the same size. For DN1000 PN40 valves, this enables manual operation with a turbine operator, eliminating the need for expensive electric actuators in some scenarios.
• Bidirectional Sealing: The fixed ball alignment ensures uniform contact between the ball and dual seats, enabling reliable sealing in both flow directions—simplifying pipeline design and eliminating the need for check valves.

B. Metal-to-Metal Hard Seal: Durability & High-Temperature Adaptability

• Wear & Corrosion Resistance: Stellite overlay on the ball and seat surfaces (hardness ≥58 HRC) resists abrasion from slurries, sand-laden oil, and other aggressive media. Stellite’s cobalt-chromium composition also provides excellent corrosion resistance, extending seal life by 50% compared to uncoated metal seals.
• High-Temperature Performance: Metal seals operate reliably up to 425℃, making the valve suitable for steam lines, high-temperature oil processing, and power generation systems. Unlike soft seals (PTFE/EPDM) that degrade at elevated temperatures, metal seals maintain structural integrity and sealing force.
• Low Leakage: Class V sealing ensures minimal leakage (≤0.01% of nominal flow), critical for handling toxic, flammable, or high-value media (e.g., natural gas, crude oil). For applications requiring zero leakage, the optional secondary soft seal upgrades performance to Class VI.

C. Premium Material Construction: Strength & Corrosion Resistance

• WCB Carbon Steel: Cost-effective and durable for non-corrosive or mildly corrosive media (water, steam, crude oil), with excellent tensile strength and impact toughness. Ideal for general industrial applications and oil & gas pipelines.
• CF8 Stainless Steel: Enhanced corrosion resistance for chloride-rich environments (coastal areas, chemical plants) and media containing mild acids or alkalis. Prevents rust and pitting, extending valve life in harsh chemical conditions.
• Stellite Overlay: Provides a hard, wear-resistant surface on the ball and seat, critical for abrasive media (slurries, coal dust) that would quickly damage soft seals or uncoated metal.

D. Turbine Manual Actuation: Precision & Ease of Use

• Torque Reduction: Gear ratio 30:1 to 100:1 reduces the force required to operate large valves, enabling single-person control even for DN1400 PN64 models. The worm gear design ensures smooth, consistent torque transmission.
• Position Indication: Clear open/closed markings on the handwheel and valve body provide instant visual confirmation of valve status, reducing the risk of human error (e.g., leaving the valve partially open).
• Durability: Cast iron housing with anti-corrosion coating protects internal gears from environmental damage, ensuring reliable operation in outdoor or harsh industrial environments.

E. Flange Connection: Compatibility & Secure Sealing

• Global Standard Compliance: ASME B16.5/GB/T 9113 flanges ensure compatibility with pipelines worldwide, eliminating the need for custom adapters. Raised Face (RF) or Ring Type Joint (RTJ) sealing surfaces accommodate different gasket types and pressure requirements.
• Secure Clamping: Uniform bolt torque (per ASME B18.2.1) ensures tight sealing between the valve and pipeline flanges, preventing leakage under pressure surges and thermal cycling.

IV. Manufacturing Process & Quality Control

A. Raw Material Procurement & Inspection

• Material Sourcing: WCB/CF8 castings, Stellite alloy, and stainless steel components are sourced exclusively from ISO 9001-certified suppliers, with each batch accompanied by a Material Test Certificate (MTC) detailing chemical composition, mechanical properties, and heat treatment history.
• Material Verification: Incoming castings undergo spectral analysis (XRF) to confirm chemical compliance with ASTM standards. Tensile, yield, and impact tests are performed on sample specimens—e.g., WCB must meet tensile strength ≥485MPa and impact toughness ≥27J at -20℃.
• Non-Destructive Testing (NDT): Cast bodies, bonnets, and balls undergo ultrasonic testing (UT) to detect internal defects (cracks, inclusions) and magnetic particle testing (MPI) to inspect surface flaws. Only defect-free materials proceed to machining.

B. Casting & Heat Treatment

• Precision Casting: WCB/CF8 billets are melted in an electric arc furnace and poured into resin-bonded sand molds using the lost foam casting process. This ensures dimensional accuracy (tolerance ±0.05mm) and surface smoothness, reducing the need for subsequent machining.
• Heat Treatment:
  • WCB components: Normalizing (890–920℃, air-cooled) to relieve casting stress and refine grain structure. Post-heat treatment hardness is 140–180 HB.
  • CF8 components: Solution annealing (1040–1150℃, water-cooled) to restore corrosion resistance and relieve stress.
  • Stellite Overlay: Applied to ball and seat surfaces via plasma welding, then ground to a spherical accuracy of ≤0.005mm and lapped to Ra ≤0.4μm.
• Descaling & Cleaning: Cast parts are shot-blasted to remove surface oxide scale, then cleaned with ultrasonic baths to eliminate residual contaminants.

C. Precision Machining

• Body & Bonnet Machining: CNC lathes and 5-axis mills process flange faces, seat pockets, and trunnion bores. Flange faces are machined to flatness ≤0.02mm/m and surface roughness Ra 1.6μm. Seat pockets are honed to coaxiality ≤0.01mm relative to the bore, ensuring uniform ball-seat contact.
• Ball Machining: Forged balls are ground to spherical accuracy ≤0.005mm, then lapped to Ra ≤0.4μm. Stellite overlay is applied to the sealing surfaces and precision-ground to ensure consistent hardness and contact pressure.
• Stem & Trunnion Machining: Stems are turned and ground to diameter tolerance ±0.01mm and polished to Ra ≤0.4μm. Trunnions are machined with precision threads for bearing installation, ensuring smooth rotation.

D. Assembly & Comprehensive Testing

1. Component Cleaning: All parts (body, ball, seats, stem, packing) are degreased and ultrasonic-cleaned to remove oil, debris, and metal particles—preventing contamination of sealing surfaces.
2. Assembly Sequence: Trunnion bearings are installed first, followed by the ball, stem, seats (with preloaded springs), packing, and bonnet. Fasteners are tightened in a crisscross pattern to uniform torque (per ASME B18.2.1) to ensure even clamping force. Actuators (pneumatic/electric) are mounted in accordance with ISO 5211 standards.
3. Pressure Testing:
   • Hydrostatic Shell Test: 1.5× rated pressure applied to the body cavity for 30 minutes—no leakage, deformation, or pressure drop permitted.
   • Hydrostatic Seat Test: 1.1× rated pressure applied to each seat (bidirectional) for 15 minutes—leakage measured via bubble counting, complying with ANSI/FCI Class V.
   • Pneumatic Test (Optional): 0.6MPa air pressure applied to the body and seats for 10 minutes—no audible leakage permitted.
4. Operational Testing: The valve is cycled 50 times (open-close) to verify smooth operation, consistent torque, and correct actuator performance (for pneumatic/electric models).
5. Specialized Testing:
   • Fugitive Emissions Test: ISO 15848-1 Class AH compliance verified with methane and flame ionization detector (FID).
   • High-Temperature Test: For high-temperature service valves, testing at 425℃ to confirm seal performance and structural integrity.

E. Final Inspection & Packaging

• Visual Inspection: Each valve is inspected for surface defects (scratches, dents), proper machining, and correct marking (DN, PN, TIANYU logo, certifications). Valves with surface scratches deeper than 0.05mm are rejected.
• Documentation: Each valve is shipped with a Documentation Package including MTC, Hydrostatic Test Certificate, EN10204 3.1/3.2 Certificate, and CE PED Declaration of Conformity.
• Packaging: Valves are packaged in plywood crates with foam insulation to prevent damage during transportation. Flange ends are capped with plastic protectors, and actuators are wrapped in waterproof film. Crates are labeled with handling instructions and product information for safe delivery.