III. Feature Description

A. Fixed Ball (Trunnion-Mounted) Design: Stability in High Pressure

• Pressure Force Distribution: Fluid pressure acts on the ball, but trunnions transfer these forces to robust bearings—preventing the ball from shifting into the valve seats. This eliminates seat deformation, a common issue in floating ball valves that increases operational torque and shortens seal life. In a DN200 PN40 natural gas pipeline, this design maintains consistent sealing for 8–12 years, compared to 3–5 years for floating ball alternatives.
• Low Operational Torque: Trunnion support reduces friction between the ball and seats, lowering torque requirements by 40–50% compared to floating ball valves. A DN200 worm gear-operated model requires only 90 N·m of torque to operate—enabling manual operation without specialized tools, even in high-pressure systems.
• High-Pressure Resilience: The trunnion structure withstands PN40–PN100 pressures without structural failure. In a petrochemical plant’s high-pressure gas feed line (PN64), the valve handles 9.6MPa pressure spikes without leakage, outperforming floating ball valves that risk seat damage under such conditions.

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

• High-Pressure Strength: Forged A105 offers superior tensile and yield strength compared to cast carbon steels (e.g., WCB), making it suitable for PN40–PN100 high-pressure applications. In hydrostatic testing, the A105 body withstands 9.6MPa (1.5× PN40) without deformation—ensuring safety in over-pressure scenarios (e.g., pump surges).
• Cost-Effectiveness: A105 is more affordable than stainless steel (e.g., 304/316) while delivering comparable strength in non-corrosive or mildly corrosive media. For large-scale projects (e.g., municipal gas networks with 100+ valves), this translates to 30–40% cost savings without compromising performance.
• Machinability & Weldability: A105’s excellent machinability enables precision CNC machining of critical surfaces (flanges, trunnion seats), ensuring dimensional accuracy within ±0.05mm. Its weldability allows for on-site modifications or repairs—critical for remote pipeline installations where valve replacement is time-consuming and costly.
• Thermal Stability: A105 retains its mechanical properties up to 425℃, making it suitable for heated media applications (e.g., steam-assisted oil recovery or industrial process gas lines) where lower-grade carbon steels would soften or deform.

C. Hard-Seal Performance: Reliability in Harsh Environments

• High-Temperature Compatibility: Stellite 6 hard-facing retains its hardness (≥58 HRC) up to 425℃, making the valve suitable for high-temperature media (e.g., industrial steam or heated gas) where soft seals (PTFE) would degrade rapidly. In a power plant’s steam auxiliary line, the hard-seal valve operated reliably for 10 years, while a soft-sealed valve required quarterly seat replacements.
• Abrasive Media Resistance: The hard-sealed surface resists wear from particulate-laden media (e.g., natural gas with fine sand or water with sediment). In a rural water distribution system, the valve withstood abrasive sediment for 8 years, outperforming soft-sealed valves that failed within 2 years due to seat wear.
• Leak-Tight Sealing: The precision-ground metal-to-metal seal achieves ANSI/FCI Class IV leakage performance (≤0.1×DN mm³/min for gas), preventing fugitive emissions of hazardous media. This compliance with environmental regulations (e.g., EPA Methane Rules) avoids costly fines and reduces safety risks in industrial or residential areas.

D. Multi-Drive Adaptability: Flexibility for Diverse Operations

• Manual Operation: Worm gear operators enable easy manual control of DN200 valves, ideal for remote locations or low-frequency use (e.g., emergency isolation in gas storage facilities). The ergonomic handwheel and 90-degree rotation reduce operator fatigue, even during frequent use.
• Pneumatic Actuation: Spring-return pneumatic actuators provide critical fail-safe operation—auto-closing the valve if air supply fails, a non-negotiable feature for gas pipelines or oil refineries. Double-acting pneumatic actuators offer rapid cycle times for high-frequency applications (e.g., batch processing in chemical plants), improving operational efficiency.
• Electric Actuation: Electric actuators with remote control capabilities integrate seamlessly with SCADA/DCS systems, enabling centralized monitoring and control. For large industrial facilities or cross-country pipelines, this eliminates the need for on-site operators, reducing labor costs and safety risks associated with manual intervention.
• Hydraulic/Electro-Hydraulic Actuation: For ultra-high-torque applications (DN300+ or PN100+), hydraulic actuators deliver precise control in heavy-industry settings (e.g., offshore oil platforms or large-scale petrochemical plants), where manual or electric actuation would be impractical.

E. Flanged Connection: Secure Installation & Maintenance Ease

• Leak-Tight Sealing: Bolted flanges distribute clamping force evenly across the gasket, ensuring a secure seal even under vibration or pressure fluctuations. In a DN200 gas pipeline, this design prevented fugitive emissions of natural gas, meeting strict safety standards for residential and industrial areas.
• Easy Installation & Retrofit: Flanges align with standard pipeline components, reducing installation time by 30% compared to welded valves. When upgrading an existing system, the valve can be installed without cutting the pipeline—minimizing downtime for utilities or industrial plants.
• Simplified Maintenance: Flanged valves can be disassembled for seat replacement or stem packing adjustment without removing the valve from the pipeline. In a petrochemical plant, this reduced maintenance time for DN200 valves from 8 hours (welded valves) to 2 hours—critical for continuous-process operations where unplanned downtime costs thousands of dollars per hour.

IV. Manufacturing Processes

A. Material Inspection & Preparation

• A105 Carbon Steel Verification: Forged A105 billets are tested via spectral analysis to confirm chemical composition (C: 0.25–0.35%, Mn: 0.60–1.00%, P ≤0.035%, S ≤0.035%) and ultrasonic testing (UT) to detect internal defects (porosity, cracks, inclusions). Mechanical testing (tensile strength, impact resistance, hardness) ensures compliance with ASTM A105 standards, with results documented in Material Test Reports (MTRs) for full traceability.
• Heat Treatment: A105 billets undergo normalizing (900–950℃, air-cooled) to relieve internal stresses from forging, improve machinability, and enhance impact resistance. This step is critical for preventing fatigue cracking in high-pressure cyclic operations.
• Hard-Seal Material Validation: Stellite 6 alloy is tested for hardness (≥58 HRC) via Rockwell testing and chemical composition (Co: 50–60%, Cr: 25–30%, W: 4–6%) to ensure wear resistance in abrasive media.

B. Valve Body & Ball Fabrication

• Body Manufacturing: A105 valve bodies and bonnets are produced via forging (for DN200) to ensure material density and structural integrity—forging eliminates internal defects common in cast components, which is critical for high-pressure applications. Forged blanks are cleaned via shot blasting to remove scale and surface impurities.
• CNC Machining: Critical surfaces—including flange faces, trunnion bearings, and seat pockets—are machined using 5-axis CNC centers. Flange faces are machined to ASME B16.5 flatness (≤0.05mm/m) and surface finish (Ra ≤3.2μm) for proper gasket seating. The ball’s spherical surface is ground to Ra ≤0.2μm using a spherical grinder, ensuring uniform contact with the hard seal. Trunnion seats are machined to a tolerance of ±0.02mm to ensure proper ball alignment.
• Hard-Seal Application: Stellite 6 is applied to valve seats via plasma transfer arc (PTA) welding—a precise process that minimizes heat input and prevents distortion of the A105 body. The welded surface is then ground to match the ball’s curvature, with a final lapping step to achieve ANSI/FCI Class IV leakage performance.

C. Trunnion & Actuator Integration

• Trunnion & Bearing Installation: Upper and lower trunnions are press-fitted into the valve body, with PTFE-impregnated bronze bearings to reduce friction. Bearings are lubricated with high-temperature grease (resistant to 200℃) to ensure smooth operation over thousands of cycles.
• Ball & Stem Assembly: The ground A105 ball is inserted into the body, and the stem is connected via a drive key—ensuring torque transfer during operation. The stem packing (graphite-PTFE) is installed in layers, with controlled compression (10–15% compression rate) to balance sealing performance and operational torque.
• Drive Mounting: Actuators (manual worm gear, pneumatic, electric) are mounted via an ISO 5211 adapter flange, with laser alignment to ensure coaxiality (stem runout ≤0.05mm)—preventing binding or premature wear. For pneumatic/electric actuators, limit switches are calibrated to trigger at fully open/closed positions, protecting seals from over-travel.

D. Quality Testing & Certification

• Hydrostatic Testing: Per API 598, the valve shell is tested at 1.5× rated pressure (9.6MPa) for 30 minutes—no leakage, sweating, or deformation is allowed. Seat testing is performed at 1.1× rated pressure (7.04MPa), with leakage measured via bubble counting (≤1 bubble per minute for Class IV).
• Pneumatic Testing: For gas service, the valve is tested with nitrogen at 0.6MPa to confirm airtight sealing—critical for preventing gas leaks in hazardous environments.
• Operational Testing: The valve is cycled 100 times (open/close) to verify smooth operation, consistent torque, and actuator response. Manual override (for pneumatic/electric models) is tested to ensure functionality during emergencies.
• Non-Destructive Testing (NDT): Welds (e.g., Stellite 6 seat welds) undergo liquid penetrant testing (PT) to detect surface cracks; the A105 body and trunnions are inspected via magnetic particle testing (MPI) to confirm structural integrity.
• Fugitive Emissions Testing: Per ISO 15848-1, the valve is tested for fugitive emissions at the stem and body-bonnet joint, meeting Class BH standards (≤100 ppmv for methane).

E. Final Inspection & Documentation

• Visual Inspection: The valve is checked for surface defects (scratches, dents), proper marking (size, pressure rating, material, serial number), and compliance with ASME B16.34. Marking is permanent (laser-etched) for traceability in industrial systems.
• Documentation: Each valve includes an MTR for A105 carbon steel, hydrostatic/pneumatic test reports, fugitive emissions test certificates, and compliance documents (API 608, ISO 9001). For hazardous area applications, ATEX/IECEx certificates are provided to confirm compliance with global safety standards.