Sealed Reliable Pressure Balanced Inverted Lubricated Oil Sealed Plug Valve for Petroleum Chemical Pharmaceutical Industries

III. Structural Design & Technical Features

1. Back Pressure Balanced Structure
   • A balancing piston at the plug base counteracts axial load using medium pressure, reducing operating torque by 40%~60% and resolving jamming issues in high-pressure applications. The balancing chamber connects to the medium channel, automatically compensating for pressure fluctuations to ensure stable operation in Class 900 systems.
2. Forced Lubrication Sealing System
   • A circular lubrication groove between the body and plug injects NLGI 2# lithium-based grease via a high-pressure grease valve, forming a dynamic sealing film (sealing specific pressure ≥12MPa) while minimizing friction wear. The grease isolates media from metal surfaces, preventing scaling and corrosion to extend valve life to 8~10 years.
3. Bi-Directional Flow & Non-Directional Design
   • Symmetric flow path eliminates the need to distinguish media direction, offering installation flexibility for bi-directional shut-off scenarios like heat exchanger inlets/outlets and tank connecting pipes. Both flow directions meet API 598 Class VI sealing standards with leakage rate ≤1×10⁻⁹m³/s.

IV. Manufacturing Processes & Quality Control

1. Core Technologies
   • Body Casting: Investment casting (lost-wax process) ensures dimensional accuracy CT6 and surface roughness Ra≤12.5μm, with critical areas ultrasonically tested (UT) for no shrinkage defects.
   • Plug Machining: CNC lathe precision turning followed by grinding polishes sealing surfaces to flatness ≤0.01mm, with fit clearance to body controlled at 0.05~0.1mm for high-pressure sealing compliance.
   • Surface Treatment: Stainless steel components passivated; cast steel parts coated with epoxy resin (thickness ≥100μm), passing 1000-hour salt spray test for marine environments.
2. Quality Certification System
   • Certifications: ISO 9001, CE (PED 2014/68/EU), API 6D (optional)
   • Testing Procedures:
     • 100% shell strength test (1.5× rated pressure, 5-min hold)
     • Bi-directional seal test (1.1× rated pressure, 15-min hold)
     • Torque fluctuation test (≤15% deviation at ambient temperature)