Welded Metal-Seated Butterfly Valve

The Welded Metal-Seated Butterfly Valve incorporates a triple-offset torque-seated geometry with direct butt-weld end connections, providing continuous zero-leakage shut-off in high-pressure and high-temperature piping systems. Built to replace flanged connections in critical lines, this full-metal valve design eliminates potential exterior leak paths, ensuring reliable isolation under harsh thermal cycling up to 550°C and pressures reaching ASME Class 600.

Frictionless Closure: Triple-eccentric shaft offset removes seating contact until final mechanical shut-off, preventing seal wear.

Hermetic Piping Integrity: Fully welded body ends remove flange gaskets, eliminating fugitive body emissions.

Bi-Directional Tightness: Metal laminated seal ring achieves ISO 5208 Rate A and API 598 zero-leakage criteria.

Fire-Safe Structure: Solid metal-to-metal seating matrix meets API 607 fire test specifications naturally.

Blowout-Proof Shaft: Internal shaft retention mechanics prevent stem displacement under maximum pressure drop.

Geometrical Offsets: Shaft center offset from pipe axis, shaft center offset from seal face, and inclined conical seat axis.

Body Configuration: Butt-weld ends machined according to ASME B16.25 standards, compatible with various wall thickness schedules.

Sealing Interface: Replaceable stainless steel/graphite laminated matrix against an integral Stellite-hardfaced body seat.

Thermal Compensation: Floating laminated disk seal allows uniform thermal expansion without binding.

Stem Packing: Die-formed flexible graphite packing stack equipped with spring washer live-loading.

The triple-offset mechanism translates 90-degree rotary action into a cam-like motion during the final degrees of closure. Disk contact occurs strictly at the final closed position, eliminating sliding friction across the sealing face. Sealing torque forces the resilient disc seal ring against the sloped conical seat, forming a tight barrier. Upon opening, the disc separates immediately from the seat without rubbing, minimizing operational torque and seat degradation.

Standard Butt-Weld Ends: Beveled edges produced to match Schedule 40, Schedule 80, Schedule 160, or specified pipe dimensions.

Extended Weld Neck: Long body extensions distance field welding heat from stem packing and internal seal rings.

Custom Bore Matching: Tapered transition machining aligns valve internal diameters with connecting pipe wall schedules.

Manual Control: Handwheel worm gear operator with position indicator and travel stops.

Pneumatic Actuation: Double-acting or spring-return rack-and-pinion / scotch-yoke actuators with positioners.

Electric Actuation: On-off or modulating multi-turn intelligent quarter-turn actuators.

Hydraulic Control: High-torque hydraulic or electro-hydraulic systems for emergency shut-off duties.

High-Pressure Steam: Main steam isolation and condensate transport lines in power facilities.

Hydrocarbon Refining: High-temperature catalytic cracking, hydro-treating, and flare gas systems.

Chemical Processing: Corrosive fluid pipelines requiring permanent welded joint containment.

District Energy: Underground superheated water and steam trunk lines.

Cryogenic Fluid Isolation: Liquefied gas lines utilizing extended bonnet configurations.

Condition Verification: Confirm working medium, pressure range, fluid velocity, and temperature limits.

Material Selection: Match WCB carbon steel for general media, WC6/WC9 alloy for high-temperature steam, or CF8M stainless steel for corrosive fluids.

Pipe Profile Matching: Specify line pipe outside diameter and wall thickness schedule to ensure accurate ASME B16.25 bevel alignment.

Actuation Sizing: Determine dynamic torque using maximum differential pressure values and apply required safety factors.

Non-Destructive Testing: Radiographic or ultrasonic inspection on pressure-retaining casting sections; liquid penetrant testing on hardfaced seat surfaces.

Pressure Testing: Shell hydrostatic test at 1.5 times working pressure rating; high-pressure closure test at 1.1 times rating per API 598.

Dimensional Verification: Weld bevel profiles, wall thicknesses, and face-to-face dimensions verified using calibrated tools.

Material Traceability: Positive Material Identification via XRF analyzer on cast bodies, discs, and shafts.

Extended Stem Bonnets: Shaft extensions for high-temperature pipe lagging or subterranean installation.

Corrosion Alloys: Castings available in Duplex stainless steel, Monel, or Hastelloy for specific chemical services.

Custom Welding Bevels: Tailored compound bevels or internal backing ring counterbores.

Surface Treatments: High-temperature inorganic zinc coatings or heavy-duty epoxy finishes.

Engineering Drawings: 2D cross-section layouts and 3D STEP models for piping CAD integration.

Flow Calculations: Valve flow coefficient (Cv/Kv) values across opening angles and pressure drop tables.

Quality Certifications: EN 10204 3.1 Material Test Reports, pressure test logs, and NDT inspection records.

Operation & Maintenance Manual: Instructions covering field welding heat control, packing adjustment, and seat maintenance.