III. Feature Description

A. Center-Line Design: Balanced Performance & Low Flow Resistance

• Uniform Seal Contact: As the disc rotates, its edges maintain equal pressure against the EPDM seat—eliminating uneven wear and ensuring consistent sealing across the valve’s lifecycle. In field tests, this design maintained Class IV leakage for 60,000+ cycles, vs. 30,000 cycles for offset-disc butterfly valves.
• Bidirectional Sealing: The center-line disc seals equally well in both flow directions, eliminating the need for check valves and simplifying pipeline layout. This is critical for systems where media flow may reverse (e.g., wastewater lift stations).
• Low Flow Resistance: The full-bore disc creates a streamlined flow path, with a flow coefficient (Cv) 2–3× higher than comparable gate valves. For a DN80 pipeline flowing 100m³/h of water, this reduces pressure drop by ≈0.5bar—cutting pump energy costs by 10–15% annually.

B. EPDM Soft Seal: Reliable Closure & Media Compatibility

• Elastic Compensation: EPDM’s flexibility compensates for minor dimensional variations in the disc or body (e.g., from thermal expansion), ensuring tight closure even if components shift slightly. This is particularly valuable in systems with cyclic temperature changes (e.g., HVAC heating/cooling loops).
• Broad Media Compatibility: EPDM resists degradation from water, steam, chlorinated disinfectants (common in water treatment), dilute acids (e.g., acetic acid), and alkalis (e.g., sodium hydroxide). It does not leach harmful substances, making food-grade EPDM suitable for potable water or beverage processing.
• Cost-Effective Sealing: Soft-seal EPDM seats are less expensive to manufacture and replace than metal seats, reducing lifecycle maintenance costs by 40–60%.

C. WCB Body & SS304 Disc: Strength Meets Corrosion Resistance

• WCB Body Strength: WCB carbon steel provides the tensile strength needed to withstand PN16 pressure (1.6MPa) without deformation. Its cast construction is cost-effective for mid-sized valves (DN80), while normalizing heat treatment eliminates internal stress that could cause cracking over time.
• SS304 Disc Corrosion Resistance: SS304 resists rust and mild chemical attack, making the valve suitable for chlorinated water (municipal treatment), coastal environments (salt air exposure), and light chemical processing. Unlike carbon steel discs, it does not require painting or coating to prevent corrosion.

D. Manual Lever Operation: Simplicity & Independence

• No Power Dependencies: Unlike pneumatic or electric valves, the lever requires no external energy source—ideal for remote locations, emergency shutdown systems, or facilities with limited power access.
• Fast On-Off Control: 90-degree rotation enables quick flow shutoff (≤5 seconds), critical for responding to pipeline emergencies (e.g., leaks) or process changes (e.g., switching production lines).
• Low Maintenance: The lever has no moving parts beyond the rotational joint, reducing failure points and maintenance needs. Routine upkeep is limited to lubricating the joint (annually) and inspecting the lever grip.

E. Compact & Lightweight Construction

• Space Efficiency: The 115mm face-to-face length is 50–70% shorter than a DN80 Class 150 gate valve (≈229mm), making it suitable for tight pipeline spaces (e.g., skid-mounted equipment).
• Easy Installation: At ≈15kg, the valve can be lifted and installed by two operators without heavy lifting equipment—reducing labor costs and installation time.

IV. Manufacturing Process & Quality Control

A. Raw Material Procurement & Inspection

• WCB Body Castings: Each casting is accompanied by a Material Test Certificate (MTC) detailing chemical composition and mechanical properties. Castings undergo ultrasonic testing (UT) to detect internal porosity or cracks, and magnetic particle testing (MPI) to inspect surface defects.
• SS304 Disc Plate: SS304 plate is verified via spectral analysis (XRF) to confirm chromium/nickel content, and tensile testing to ensure strength ≥515MPa.
• EPDM Seat Material: EPDM resin is tested for hardness (70 Shore A), tensile strength (≥10MPa), and compliance with ASTM D2000. Food-grade EPDM is additionally tested for FDA 21 CFR 177.2600 compliance.

B. Body Manufacturing

• Casting: Resin-bonded sand molds are used to create the body cavity, with mold temperature maintained at 200–250℃ to ensure uniform solidification. Molten WCB steel (1500–1550℃) is poured into the mold at a controlled rate (0.5–1.0m/s) to minimize porosity.
• Heat Treatment: Cast bodies are normalized (890–920℃, 1–2 hours, air-cooled) to relieve stress and refine grain structure. Post-heat treatment hardness is 140–180 HB.
• Machining: CNC lathes and mills process the body to ASME B16.34 tolerances:
  • Flange faces are machined to flatness ≤0.02mm/m and surface roughness Ra 1.6μm.
  • The seat groove is machined to a depth tolerance of ±0.05mm, ensuring a tight fit for the EPDM seat.
  • The stem hole is drilled and reamed to coaxiality ≤0.02mm relative to the body axis.

C. Disc & Stem Manufacturing

• Disc Production: SS304 plate is stamped or forged into the disc shape, then turned to the correct diameter (DN80) with a sealing edge tolerance of ±0.03mm. The sealing surface is polished to Ra ≤1.6μm using a wet grinding process.
• Stem Production: SS304 bar stock is turned to the correct diameter (±0.01mm) and polished to Ra ≤0.4μm. The anti-blowout shoulder is machined to engage the body’s stem bore, and a keyway is cut to connect to the disc.

D. Seat Installation & Assembly

• Seat Installation: The EPDM seat is pressed into the body’s seat groove with a hydraulic press (5–10kN force) to ensure uniform contact. For food-grade applications, the seat is bonded to the groove using FDA-compliant adhesive.
• Stem & Disc Assembly: The stem is inserted into the body’s stem bore, then connected to the disc via a keyway (secured with a retaining ring). The stem packing (EPDM/PTFE composite) is installed in layers, with each layer compressed to 10–15% of its original thickness.
• Lever Attachment: The manual lever is bolted to the stem’s top end, with a set screw to lock it in place. The lever is adjusted to ensure 90-degree rotation (open = lever parallel to pipeline; closed = lever perpendicular).

E. Testing & Quality Assurance

• Hydrostatic Shell Test: 1.5× rated pressure (2.4MPa) is applied to the body cavity for 30 minutes. No leakage, deformation, or pressure drop is permitted.
• Hydrostatic Seat Test: 1.1× rated pressure (1.76MPa) is applied to each flow direction for 15 minutes. Leakage is measured via bubble counting—Class IV compliance requires ≤1 bubble/minute for DN80.
• Operational Test: The valve is cycled 50 times (open-close) to verify smooth rotation, correct lever alignment, and consistent torque.
• Final Inspection: Visual checks confirm no surface defects, proper marking (DN80, PN16, TIANYU logo), and compliance with dimensional specifications.