Full Manufacturing Process of J-VALVES Trunnion Mounted Ball Valves | Strict Machining Procedures for Zero Leakage High Pressure Ball Valves

All trunnion ball valve bodies are formed via die forging technology to eliminate porosity and blowhole defects common in cast valve bodies. Carbon steel valve bodies adopt A105 forged steel and WCB forgings, while stainless steel / duplex steel valve bodies are integrally forged. All incoming raw materials undergo spectrometric material re-inspection, and unqualified materials are rejected directly.

In the rough machining stage, large floor boring machines are used for cavity machining and flange through-hole processing with allowances reserved for finish machining. Meanwhile, UT and MT non-destructive testing are performed on valve bodies to detect potential internal cracks in forgings, eliminating the risk of burst failure under high pressure from the very beginning.

• CNC lathes perform rough and finish turning on ball blanks to guarantee basic spherical dimensional accuracy;

• Stainless steel balls undergo low-temperature nitriding heat treatment to boost surface hardness, delivering superior wear and erosion resistance;

• Specialized ball lapping equipment conducts progressive polishing with multi-grade abrasive paper and diamond compound. The final spherical surface roughness reaches Ra0.02μm, achieving perfect contact with valve seat sealing faces and Class VI zero leakage tightness.

  As shown in the workshop photos of mass-produced large-bore trunnion ball valves, all balls are self-lapped in-house. There is no risk of sealing gaps caused by low-quality outsourced rough balls.

Valve seats for trunnion mounted ball valves adopt Stellite hardfacing overlay welding technology. After overlay welding, CNC finish turning is carried out on sealing bevels with tolerances controlled within ±0.002mm. Valve stems are integrally forged, with anti-blowout limit grooves and anti-static conductive structures machined to comply with API 6D fire-safe and anti-static standards.

All sealing components are manufactured matched in the same factory, boasting far superior dimensional compatibility compared to valves assembled from outsourced scattered parts. The valves operate smoothly without jamming during high-low pressure switching, with stable sealing resilience.

Fully machined valve bodies, balls and seats are transferred to a closed dust-free assembly workshop. All staff wear dust-free work uniforms to clear metal burrs and dust particles from every component, preventing tiny debris from scratching sealing surfaces.

Worm gear operators and electric actuators are pre-installed simultaneously on large-bore trunnion ball valves. Technicians adjust switching torque and valve position indicators, complete anti-static grounding and fill fire-resistant sealing packing. All finished valves feature neat uniform appearance. As seen in the photos of mass-completed trunnion ball valves, standardized unified assembly processes ensure consistent performance of every single unit.

1. Shell hydrostatic strength test: Hold 1.5 times the rated pressure for 30 minutes with zero seepage;

2. High-pressure pneumatic seat tightness test: Hold 1.1 times the rated pressure for 5 minutes with zero bubble leakage;

3. Low-pressure air tightness retest: Simulate low-pressure pipeline operating conditions to verify sealing compensation performance.

   Any valve failing the pressure tests will be disassembled and reworked immediately. All test data are archived permanently, and official pressure test certificates are supplied together with shipments for clients to trace inspection records at any time.