III. Feature Description

A. Double Eccentric Structure: Low Wear & Extended Service Life

• Friction Reduction: Unlike concentric valves (where disc and seat rub throughout the stroke), the double eccentric design lifts the disc away from the seat during opening, minimizing contact to only the final 5–10° of closure. This reduces seal wear by 70% compared to concentric models, extending service life from 3–5 years to 8–12 years in typical water applications.
• Uniform Sealing Pressure: The second eccentricity ensures the disc presses evenly against the seat, creating a tight seal across the entire contact surface. This eliminates leakage points caused by uneven pressure, critical for water media where even minor leakage wastes resources or disrupts processes.
• Bidirectional Sealing: The design enables reliable sealing in both flow directions, eliminating the need for check valves in bi-flow systems (e.g., municipal water mains with reverse flow during maintenance).

B. Dual Sealing Options: Adaptability to Diverse Conditions

• PTFE Soft Seal: Ideal for low-to-medium temperature water systems (≤200℃) such as municipal drinking water, HVAC chilled water, and industrial process water. PTFE’s chemical inertness resists corrosion from chlorinated water or mild impurities, while its elasticity delivers ANSI Class VI bubble-tight sealing—critical for potable water networks to prevent contamination.
• Metal Hard Seal (Stellite 6): Engineered for high-temperature (≤400℃) and high-pressure (≥PN4.0MPa) water systems, such as power plant boiler feedwater, industrial steam condensate, or water with fine abrasive particles (e.g., river water intake). Stellite 6’s extreme hardness (≥58 HRC) resists wear and deformation, maintaining ANSI Class IV leakage performance even after 10,000+ cycles.

C. Manual Operation: Cost-Effective & Easy to Maintain

• Locations without power access (e.g., remote water pumping stations, rural irrigation systems).
• Low-frequency operation scenarios (e.g., pipeline maintenance isolation, seasonal flow adjustment).
• Budget-sensitive projects (e.g., small municipal wastewater plants, residential building water lines).

  The ergonomic design ensures ease of use: lever operation for small valves takes only 1–2 seconds per cycle, while gear-reduction handwheels allow single-person control of DN3000 valves with minimal effort.

D. Wide Diameter Range: Scalability Across Applications

• Small Diameters (DN50–DN200): Used in residential building water supply, HVAC terminal units, and small industrial process lines. Lever operation and compact design save space and installation costs.
• Medium Diameters (DN250–DN1000): Deployed in municipal water distribution networks, industrial cooling water circuits, and wastewater treatment plant process lines. Gear-reduction handwheels balance torque and operation efficiency.
• Large Diameters (DN1200–DN3000): Installed in large-scale water mains, reservoir intake/outlet lines, and industrial cooling towers. Robust construction with reinforced valve bodies and shafts withstands high flow velocities and pressure fluctuations.

E. Durable Material Selection: Corrosion Resistance & Longevity

• Stainless Steel (304/316): Resists rust and pitting from chlorinated water, seawater, and industrial wastewater, making it suitable for coastal municipalities and chemical plants.
• Cast Steel (WCB): Offers high tensile strength and thermal stability for high-pressure/high-temperature water systems, such as power plant auxiliary lines.
• Ductile Iron (QT450-10): Cost-effective and impact-resistant for low-pressure municipal applications, with epoxy coating enhancing corrosion resistance in buried pipelines.
• Stellite 6: Ensures metal seal durability in abrasive or high-temperature water, outperforming carbon steel seals by 3–4 times in service life.

IV. Manufacturing Processes

A. Material Inspection & Preparation

• Raw Material Verification: All metallic materials undergo rigorous testing to ensure compliance with standards:
  • Stainless steel (304/316) and cast steel (WCB) billets are tested via spectral analysis to confirm chemical composition (e.g., Cr: 18–20% for 304, C: 0.25–0.35% for WCB). Ultrasonic testing (UT) and magnetic particle inspection (MPI) detect internal defects (porosity, cracks) in cast components.
  • Ductile iron (QT450-10) is tested for tensile strength and impact resistance, ensuring compliance with ASTM A536.
  • PTFE seal materials are inspected for compression set (≤20% after 70 hours at 200℃) and chemical purity, meeting FDA 21 CFR 177.1550 standards for food-grade water applications.
• Surface Preparation:
  • Cast components are sandblasted to remove scale and surface defects, improving paint adhesion (for ductile iron) or passivation (for stainless steel).
  • Stainless steel components undergo acid passivation to enhance the chromium oxide passive layer, boosting corrosion resistance.
  • Valve stems are precision-ground to a surface roughness of Ra ≤0.4μm to reduce friction with packing.

B. Precision Machining of Double Eccentric Structure

• Valve Body Machining: CNC turning and milling centers shape the valve body, with flange faces machined to flatness tolerance ≤0.05mm/m and surface finish Ra ≤3.2μm for proper gasket seating. Internal seat pockets are honed to a diameter tolerance of H7 (0–+0.03mm) to ensure precise fit with seals.
• Disc Machining: The double eccentric disc is CNC-machined to spherical tolerance ±0.02mm, with seal faces lapped to Ra ≤0.8μm. For metal-sealed valves, Stellite 6 is welded to the disc and seat via TIG welding, then ground to a uniform thickness of 1.5–2.0mm.
• Shaft Machining: Valve shafts are turned, ground, and polished to diameter tolerance h7 (±0.015mm), with keyways machined to fit levers/handwheels securely. Anti-blowout shoulders are integrated into the shaft design to prevent ejection under pressure.

C. Seal Installation & Assembly

• Soft Seal Installation: PTFE seats are precision-cut to match the disc’s curvature, then press-fitted into the valve body with retaining rings. Spring-loading (optional) compensates for thermal expansion and wear, maintaining sealing pressure over time.
• Hard Seal Installation: Stellite 6-sealed seats are welded to the valve body, then lapped with the disc to ensure uniform contact. The disc is adjusted to ensure 0.1–0.2mm preload against the seat for tight sealing.
• Final Assembly: The disc-shaft assembly is inserted into the valve body, with bronze or PTFE packing installed around the shaft to prevent water leakage. Levers or gear-reduction handwheels are mounted, and torque is calibrated to ensure smooth 90° rotation.

D. Quality Testing & Certification

• Hydrostatic Testing:
  • Shell Test: The valve body is filled with water and pressurized to 1.5×rated pressure for 30 minutes. No leakage, sweating, or deformation is allowed—test results are documented in a hydrostatic test report.
  • Seat Test: The valve is closed, and water is pressurized to 1.1×rated pressure on one side. Leakage is measured via a flow meter: ≤0.1×DN mm³/min for PTFE seals (ANSI Class VI) and ≤0.01% of rated flow for metal seals (ANSI Class IV).
• Operational Testing:
  • The valve undergoes 100 open-close cycles to verify smooth operation. Torque is recorded at each cycle (variation ≤5%) to ensure consistency.
  • Lever/handwheel operation is tested to confirm single-person operation for all diameters, with torque values documented for reference.
• Dimensional Inspection: Flange dimensions, face-to-face length, and eccentricities are verified using coordinate measuring machines (CMM) to comply with ASME B16.5 and GB/T 12238.
• Certification Documentation: Each valve is accompanied by a Material Test Report (MTR), hydrostatic test report, and compliance certificates (ISO 9001, CE, API 609 if applicable).