III. Features Description

• Bellow Seal Zero Leakage: The metal bellow is welded to the stem and bonnet, creating a permanent metal barrier that eliminates stem leakage. Unlike traditional packing seals that degrade over time and require frequent maintenance, this design ensures long-term sealing integrity—critical for preventing steam or oil leakage in high-temperature systems.
• Dual Sealing Backup: Combines bellow seal (primary) and packing seal (secondary). If the bellow is damaged, the packing immediately acts as a backup to prevent leakage, providing time for scheduled maintenance and avoiding unplanned shutdowns.
• Cone-Shaped Disc for Tight Sealing: The disc features a cone structure that fits precisely with the seat, enhancing sealing performance and extending service life. This design ensures reliable shutoff even after frequent operation, reducing the need for replacement.
• Integrated Lubrication Design: The bonnet is equipped with a lubrication port, allowing direct lubrication of the stem, nut, and sleeve without disassembling the valve. This simplifies maintenance and ensures smooth operation over time.
• WCB Material Durability: WCB cast steel resists high temperatures and pressure, maintaining structural stability in steam and oil environments. It avoids deformation or cracking, ensuring long-term reliability in industrial use.

IV. Manufacturing Processes

• Material Preparation: WCB cast steel ingots undergo strict quality inspection, including chemical composition analysis (to ensure carbon content and alloy proportions meet standards) and ultrasonic testing to detect internal defects.
• Bellow Forming: Stainless steel sheets are rolled and welded into corrugated bellows, then precision-welded to the stem and bonnet using automatic rolling welding technology. Helium leak testing is performed to confirm hermetic sealing.
• Precision Machining: The valve body, disc, and seat are machined using CNC equipment to ensure dimensional accuracy. The disc and seat sealing surfaces are ground to a smooth finish (Ra ≤1.6μm) for tight contact.
• Assembly & Testing:
  • Components are assembled with precise torque to ensure stability, including the bellow, stem, disc, and handwheel.
  • Hydrostatic testing is conducted at 1.5×rated pressure (e.g., 3.75MPa for PN25) to verify the valve body’s pressure resistance; seat sealing is tested at 1.1×rated pressure to ensure no leakage.
  • Operational testing involves 100+ open/close cycles to confirm smooth handwheel operation and consistent sealing performance.