What is a Fully Welded Ball Valve?

A fully welded ball valve is an integrated welded industrial shut-off valve widely used in long-distance oil and gas pipelines, urban gas, heating, power and chemical buried pipelines. It suits high-pressure, wide-temperature, buried and corrosive particle media. Unlike split ball valves, its valve body is fully welded without split bolt flanges, with fixed and floating ball structures, butt-welded ends as standard, and optional flange/thread connections. It supports soft sealing for clean media and metal hard sealing for high-temperature, abrasive working conditions.

Core Components: It consists of an integral welded valve body, ball, trunnion supports, spring preloaded valve seats, anti-blowout valve stems and sealing assemblies.
Integrated welded body: Forged alloy steel body welded into a whole with full non-destructive testing. No split flanges or gaskets, eliminating main body leakage points and resisting pipeline bending, seismic and soil extrusion stress for buried use.
Precision ball: High-strength alloy ball polished, nitrided or hard-surfaced for high hardness and smoothness. Full bore design minimizes flow resistance. Fixed ball types adopt double trunnions to reduce rotation friction.
Spring preloaded valve seats: Disc/cylindrical springs maintain stable sealing pressure under varying temperature and pressure. Dual fire-safe sealing and double piston bidirectional shut-off structures are available, with stem emergency grease injection to stop fugitive emissions online.
Standard auxiliary structures: Built-in cavity overpressure relief, anti-static and fire-safe structures complying with industrial safety standards.

The ball rotates 90° to open or close the valve. When the ball channel aligns with the pipeline, fluid flows through; after 90° rotation, the spherical surface blocks the pipeline. Preload from disc springs forms initial sealing force, and medium pressure further compresses the seat against the ball for self-tightening zero leakage. In fully open/closed states, sealing surfaces are isolated from media to avoid erosion. It operates quickly with low torque and adapts to high-temperature, high-pressure and particle-laden harsh media.

1.Near-zero external body leakage without flange gaskets, solving long-term leakage risks of split valves.
2.High integral structural strength to resist pipeline stress and temperature cycle deformation.
3.Low construction cost for buried projects: only small shallow wells instead of large valve pits.
4.Ultra-long service life matching pipeline design cycle (over 30 years) with minimal routine maintenance.
5.Compact and lightweight, easy transportation and compact pipeline layout; complete safety configurations for flammable, explosive media.

Body structure: Integrated welded one-piece body vs bolt-connected split body with gaskets.
Leakage risk: Almost no body leakage vs high leakage risk from aging gaskets and loose bolts.
Buried suitability: Optimized for underground burial vs not recommended for long-term burial.
Maintenance: Long maintenance-free cycle vs frequent bolt tightening and gasket replacement.
Disassembly: Body cannot be separated on site vs easy internal component replacement by removing flanges.
Application: Long-distance buried trunk pipelines vs above-ground low-pressure pipelines requiring frequent disassembly.

It serves as core cut-off equipment for oil & gas transmission lines, municipal buried gas and heating networks, power high-temperature steam pipelines, chemical corrosive medium pipelines, and underground pipelines with difficult later maintenance.