III. Product Features

• API 6D-Compliant Pipeline Readiness: The full-bore design accommodates pipeline pigs for cleaning and inspection, eliminating flow restrictions and ensuring system maintainability . Automatic cavity pressure relief prevents dangerous pressure buildup when trapped media expands due to temperature fluctuations—a critical safety feature for gas and volatile liquid service .
• Dual-Seal Adaptability: Soft PTFE/PPL seats deliver bubble-tight shutoff (API 598 Class VI) for clean media like natural gas or refined oil, reducing fugitive emissions and meeting environmental regulations such as EPA’s Methane Emission Reduction Program . Metal seats (316 stainless steel) withstand high temperatures and abrasive media, maintaining sealing integrity in steam lines or crude oil applications with minor particulates .
• Enhanced Safety Systems: The fire-safe design activates a secondary metal-to-metal seal if soft seats degrade during combustion, ensuring the valve remains leak-tight for 30 minutes per API 607 . An anti-static spring bridges the ball and body, dissipating electrostatic charges to prevent ignition in flammable environments . Optional DBB functionality isolates upstream and downstream pressure sources and vents cavity media, simplifying maintenance and leak detection .
• Robust Material Performance: WCB carbon steel undergoes normalizing heat treatment (850–900℃, air-cooled) to relieve internal stress and eliminate casting defects like porosity, ensuring structural integrity under Class 300 pressure . The 316 stainless steel ball and stem resist pitting corrosion from moisture and mild chemicals, extending service life in coastal or humid environments .
• Versatile Actuation and Control: Manual worm gear operators reduce torque requirements, enabling easy operation even for large-diameter valves (DN200) . Electric and pneumatic actuators support remote control via SCADA systems, ideal for pipeline networks where on-site access is limited . Smart positioners (optional) provide precise flow modulation for process optimization in refineries or chemical plants .
• Global Interchangeability: Compliance with ASME B16.5 (flanges), API 6D (dimensions), and DIN standards ensures the valve integrates seamlessly into international projects—eliminating the need for custom adapters or modifications . Multi-standard compatibility reduces inventory costs for global operators .

IV. Manufacturing Process

• 1. Raw Material Sourcing and Inspection: WCB carbon steel ingots and 316 stainless steel blanks are sourced from certified suppliers and tested to verify compliance with ASTM standards. Chemical composition analysis (via optical emission spectrometry) confirms WCB’s carbon content (0.25–0.35%) and 316’s chromium (≥16%) and molybdenum (≥2%) levels . Mechanical testing (tensile, hardness) validates WCB’s tensile strength (≥485 MPa) and 316’s yield strength (≥205 MPa) .
• 2. Valve Body and Bonnet Casting: WCB body and bonnet are produced via sand casting with resin-bonded molds to ensure dimensional accuracy. The casting process incorporates risers to prevent shrinkage defects, and all castings undergo non-destructive testing (NDT) including ultrasonic testing (UT) and liquid penetrant testing (PT) to detect internal porosity or cracks .
• 3. Heat Treatment: Cast WCB components are normalized at 880℃ (held for 1 hour) and air-cooled to relieve internal stress and enhance impact resistance. 316 stainless steel ball and stem blanks undergo solution annealing (1050–1100℃) and water quenching to restore corrosion resistance .
• 4. CNC Precision Machining: Critical surfaces are machined using 5-axis CNC centers to achieve tight tolerances (±0.05mm). Flange faces are milled to ASME B16.5 RF/RTJ specifications, with bolt holes drilled via coordinate measuring machine (CMM) for alignment . The ball is ground to a mirror finish (Ra ≤0.8μm) to ensure uniform contact with seats, minimizing friction and leakage .
• 5. Seat Preparation and Installation: Soft seats (PTFE/PPL) are compression-molded to match seat groove dimensions and bonded with high-temperature adhesive to prevent displacement. Metal seats (316) are precision-ground to Ra ≤0.4μm and press-fitted into the valve body, with laser welding for permanent attachment .
• 6. Stem and Packing Assembly: The 316 stem is inserted into the bonnet, with a multi-layer graphite packing gland compressed to form a gas-tight seal. A blowout-proof retainer secures the stem, preventing ejection under pressure . An anti-static spring is installed between the stem and body to ensure electrical continuity .
• 7. Ball and Valve Core Integration: The 316 ball is mounted on the stem, with guided alignment to ensure the ball’s bore aligns with the flow path when open. The bonnet is bolted to the body using ASTM A320 L7 alloy steel bolts, torqued to ASME B16.34 specifications .
• 8. Actuator Mounting: For automated models, electric/pneumatic actuators are mounted via ISO 5211 brackets. The actuator’s drive shaft is coupled to the valve stem, with torque calibration (50–200 N·m, depending on valve size) to prevent motor overload . Manual worm gear operators are assembled with position indicators and locking devices .
• 9. Pressure Testing (API 598/6D):
  • Shell Test: The valve body is filled with water and pressurized to 1.5× nominal pressure for 10 minutes. No leakage or deformation is allowed, verified via ultrasonic leak detectors .
  • Seat Test: Gas (0.6 MPa nitrogen) is applied to the inlet, with leakage measured using a bubble counter. Soft-seated valves must meet API 598 Class VI (≤0.15 mL/min for DN100), while metal-seated models comply with Class IV .
  • Backseat Test: The stem packing is tested at 1.5× nominal pressure to ensure no leakage between the stem and bonnet .
• 10. Fire-Safe and Anti-Static Testing: Valves with fire-safe design undergo API 607 testing—exposed to 750–800℃ flame for 30 minutes, then cooled and tested for leakage . Anti-static performance is verified with a resistance tester (≤10Ω) .
• 11. Surface Treatment: WCB components are shot-blasted to Sa2.5 standard, then coated with two layers of epoxy paint (dry film thickness ≥120μm) for corrosion resistance. Stainless steel parts are passivated in nitric acid to enhance rust protection .
• 12. Final Inspection and Documentation: Each valve undergoes dimensional verification via CMM, with laser marking applied to the body indicating DN, pressure class, material, serial number, and certification marks. A complete quality dossier—including material certificates, heat treatment records, and test reports—is provided with each unit .