III. Feature Description

A. Dual-Disc Design: Low Flow Resistance & Rapid Closure

• Reduced Flow Resistance: The two discs open symmetrically, creating a near-full-bore flow path. This design reduces pressure drop by up to 30% compared to single-disc check valves, making it ideal for systems where energy efficiency is critical (e.g., pump discharge lines in water treatment plants).
• Rapid, Positive Closure: When media flow reverses, the dual discs close simultaneously under gravity and reverse pressure, minimizing the time window for backflow. In a chemical reactor feed line, this rapid closure prevents catalyst-laden media from flowing back into upstream tanks, avoiding costly process contamination.
• Balanced Closing Force: The dual-disc design distributes the closing force evenly across both sealing faces, reducing wear and extending seal life by 2–3 times compared to single-disc valves. In high-cycle applications (e.g., reciprocating pump discharge lines), this translates to lower maintenance costs and fewer unplanned shutdowns.

B. Hard-Seal Performance: Reliability in Harsh Environments

• High-Temperature Tolerance: Stellite 6 sealing faces maintain integrity up to 425℃, making the valve suitable for steam lines in power plants or hot oil lines in refineries—applications where soft-sealed check valves would degrade rapidly.
• Abrasive Media Resistance: The hardfaced sealing surfaces resist wear from particulate-laden media (e.g., slurry in mining operations or sand in natural gas pipelines). In a coal-fired power plant’s ash-handling system, the hard-seal valve operated reliably for 5 years, while a soft-sealed valve required monthly seal replacements.
• Leak-Tight Sealing: The precision-ground metal-to-metal seal achieves ANSI/FCI Class IV leakage performance, ensuring minimal to no media loss. In a petroleum pipeline, this prevents fugitive emissions of hydrocarbons, supporting environmental compliance and safety.

C. Wafer Connection: Installation Flexibility & Space Efficiency

• Easy Installation: The valve is sandwiched between pipeline flanges and secured with bolts, eliminating the need for dedicated valve flanges. In a crowded refinery piping rack, this space-saving design allows installation where traditional flanged valves would not fit.
• Retrofitting Simplicity: When upgrading an existing system, the wafer check valve can be installed without modifying pipeline flanges, reducing downtime and labor costs. For example, in a chemical plant’s retrofitting project, installing 20 wafer check valves saved 3 days of shutdown time compared to using flanged valves.
• Lightweight & Cost-Effective: Wafer valves are lighter and require fewer materials than flanged valves, lowering shipping and installation costs. For large-scale projects (e.g., municipal water mains), this translates to significant cost savings across hundreds of valves.

D. A105 Carbon Steel Construction: Strength & Cost-Effectiveness

• Mechanical Strength: A105’s tensile and yield strength exceed those of cast carbon steels (e.g., WCB), making it suitable for Class 300+ pressure ratings. In an offshore oil platform’s wellhead manifold, A105 valves withstand cyclic pressure loads without fatigue cracking.
• Corrosion Resistance in Mild Environments: While not as corrosion-resistant as stainless steel, A105 performs well in non-corrosive or mildly corrosive media (e.g., oil, natural gas, and treated water). For applications with moderate corrosion risks, optional galvanizing or coating can enhance longevity.
• Cost-Effectiveness: A105 is widely available and less expensive than stainless steel or alloy alternatives, making it ideal for large-scale projects where budget constraints exist without compromising performance.

IV. Manufacturing Processes

A. Material Inspection & Preparation

• A105 Verification: Raw material billets undergo spectral analysis to confirm chemical composition (C: 0.25–0.35%, Mn: 0.60–1.00%) and ultrasonic testing to detect internal defects (porosity, cracks). Mechanical testing (tensile, impact) ensures compliance with ASTM A105 standards.
• Hardfacing Material Testing: Stellite 6 alloy is tested for chemical composition (Co: 50–60%, Cr: 25–30%) and hardness (≥58 HRC) via Rockwell testing, ensuring wear resistance meets industrial requirements.

B. Valve Body & Disc Fabrication

• Forging/Casting: The valve body is produced via forging (preferred for A105 to ensure density) or sand casting. Forged bodies undergo normalizing (900–950℃, air-cooled) to relieve internal stresses and improve machinability.
• Machining: CNC turning and milling centers shape the body, discs, and flange faces. The dual-disc sealing faces are precision-ground to a surface finish of Ra ≤0.8μm, ensuring uniform metal-to-metal contact. Flange dimensions are machined to ASME B16.5 standards, with flatness tolerance ≤0.05mm/m.
• Hardfacing Application: Stellite 6 is applied to the disc sealing faces via plasma transfer arc (PTA) welding. The welded surface is then ground to restore flatness and achieve the required surface finish.

C. Assembly & Quality Testing

• Component Assembly: The dual discs are mounted on the hinge pin, with precision bearings to ensure smooth pivoting. The body gasket and fasteners are installed, with torque applied per ASME B18.2.1 specifications to ensure uniform clamping.
• Hydrostatic Testing: The valve undergoes shell testing at 1.5× Class 300 rated pressure (6.0MPa) and seat testing at 1.1× rated pressure (4.4MPa), with a 30-minute hold time. No leakage, sweating, or deformation is allowed.
• Operational Testing: The valve is subjected to forward and reverse flow tests to verify opening pressure (≤1.5% of rated pressure for smooth operation) and closing tightness (ANSI/FCI Class IV).
• Non-Destructive Testing (NDT): Critical welds (if any) undergo liquid penetrant testing (PT) to detect surface cracks; the hinge pin is inspected via magnetic particle testing (MPI) for structural integrity.

D. Final Inspection & Documentation

• Visual Inspection: The valve is inspected for surface defects, proper marking (size, pressure rating, material, serial number), and compliance with ASME B16.34.
• Documentation: Each valve is accompanied by a Material Test Report (MTR) for A105 steel, hydrostatic test report, and compliance certificates (API 594, ISO 9001).