The Fully Welded Trunnion-mounted Ball Valve: A Cornerstone of Modern Pipeline Integrity

In the vast, high-stakes world of hydrocarbon transport and critical process control, few components are as quietly pivotal as the Fully Welded Trunnion-mounted Ball Valve. Engineered to eliminate every potential leak path while withstanding punishing pressures and temperature swings, this valve has become the default choice for operators who demand 30-year service life with little intervention. From Siberian gas trunk lines to offshore LPG loading arms, the Fully Welded Trunnion-mounted Ball Valve is the sentinel that keeps hydrocarbons moving safely and efficiently.

One-Piece Body, Zero Leak Paths
Traditional flanged or bolted valves inevitably create gasketed joints—each a potential weak point. By contrast, the Fully Welded Trunnion-mounted Ball Valve uses a forged or fabricated barrel that is circumferentially welded after the internals are loaded. The result is a monocoque pressure vessel whose only openings are the pipeline ends themselves. For underground or subsea installations, where excavation is prohibitively expensive, the Fully Welded Trunnion-mounted Ball Valve becomes a fit-and-forget asset.

Trunnion Support: Strength Under Pressure
Inside the barrel, the ball is not free-floating but is instead anchored at top and bottom by precision trunnions. The trunnions absorb line thrust, so seat rings only need to provide sealing—not structural support. This dual-bearing arrangement slashes operating torque by up to 70 % compared with floating-ball designs, allowing smaller actuators and lower air or electrical consumption . Even at Class 2500 (PN 420) ratings, the Fully Welded Trunnion-mounted Ball Valve cycles smoothly, making it proper for remote actuation in unmanned compressor stations.

Materials and Metallurgy for Every Service
Whether the medium is sweet crude at 90 °C, LNG at –162 °C, or corrosive sour gas containing H₂S, the Fully Welded Trunnion-mounted Ball Valve can be tailored with a spectrum of materials. Standard builds use forged A105 carbon steel or low-temperature LF2; stainless 316L or duplex 2205 provide corrosion resistance; Inconel 625 overlays protect sealing faces in severely erosive service.

Double Block & Bleed and Pigging Compatibility
Many pipeline codes now require double isolation for maintenance or meter proving. The Fully Welded Trunnion-mounted Ball Valve obliges with double piston-effect seats that create two independent seals, upstream and downstream. A bleed valve between the seats vents the cavity, confirming integrity and allowing safe removal of downstream equipment. The full-bore, smooth-bore design also supports pipeline pigging for cleaning and inspection, eliminating the need for reduced-port valves or barrel swages .

Installation Economics
Although the upfront cost of a Fully Welded Trunnion-mounted Ball Valve is higher than a split-body equivalent, lifecycle economics strongly favor the welded solution. Eliminating bolted joints removes gasket replacement, fugitive-emission monitoring, and costly flange corrosion repairs. A 42-inch pipeline study showed that choosing the welded valve reduced 30-year total cost of ownership by 34 % compared with flanged alternatives . When installed in sleeves or valve vaults, the valve’s compact spherical body reduces excavation volume, further reducing civil costs.

A Global Standard
Major operators from Norway’s Equinor to China’s CNPC specify the Fully Welded Trunnion-mounted Ball Valve in their corporate standards. Sizes span 2″ to 60″ (DN 50–1500), pressure classes 150–2500, and temperature ratings from –46 °C to +200 °C . Optional extended stems and buried-service coatings allow direct burial without vaults, while subsea models feature cathodic protection and hyperbaric actuators rated to 3000 m seawater.

Zhejiang Naishi Valve Co., Ltd. specializes in the manufacturing of a comprehensive range of ball valves, adhering to international standards such as ASME, ANSI, EN, BS, DIN, API, GB, and GOST. Our product dimensions span from DN10 to DN1600, encompassing a diverse portfolio that includes track ball valves, forged steel high-pressure gas ball valves, fully welded ball valves, floating ball valves, fixed ball valves, high-temperature wear-resistant ball valves, DBB double ball valves, and special stainless steel and high-nickel alloy ball valves. Our valves are designed to withstand a variety of conditions, including high temperatures up to 600°C, low temperatures as low as -196°C, and high pressures reaching 4500Lb, ensuring product reliability in the demanding environments.

Leveraging a well-trained team of professionals, solid technical expertise, an efficient management system, and meticulous production management, Naishi Valve is committed to delivering high-quality ball valve solutions for industries such as oil and gas transportation, urban heating, gas, petrochemicals, chemicals, energy, power stations, and metallurgy.