Specification
Nwv Large-Diameter Concentric Soft-Seal Flanged Butterfly Valve:with Replaceable Seat, Low Torque, Bare Shaft, zero Leakage
I. Product Technical Positioning
The Nwv large-diameter concentric soft-seal flanged butterfly valve is specially designed for fluid control in large pipe diameters ranging from DN300 to DN2400 (12″ to 96″). Adopting a concentric structure (with the stem, disc, and pipeline centerline coaxial), it uses ductile iron (DI) or stainless steel (CF8/CF8M) as the main material, suitable for PN10-PN16 (1.0-1.6MPa) pressure classes. The valve connects to pipelines via double flanges (complying with EN1092 standards) and can be equipped with worm gear, electric, or pneumatic drives. It is ideal for high-flow applications in water treatment, municipal pipe networks, oil & gas transportation, and building HVAC systems, especially for clean media like water, air, and oil at normal to medium temperatures (-20°C to 120°C).
II. Core Product Features
(A) Concentric Structure & Soft Seal Design
Concentric Layout:
The stem axis aligns with the disc center and pipeline centerline. The disc rotates around the axis, completing opening/closing within a 90° stroke, featuring a simple structure and low flow resistance (flow coefficient Cv ≥10,000, pressure loss ≤0.5m water column for DN1000).
Replaceable Soft Seal Seat:
The seat uses EPDM/NBR rubber (compression set ≤8% at 120°C×72h), fixed by dovetail grooves or pressure rings for online replacement when worn, reducing maintenance costs by 40% compared to hard-seal valves. The rubber-clad disc edge ensures zero-leakage sealing (leakage rate ≤5×10⁻⁸m³/s, conforming to EN12266).
(B) U-Section Flange & Low-Torque Operation
U-Section Flange Structure:
The valve body flange adopts a U-shaped cross-section design to enhance structural rigidity for large diameters (flange thickness ≥34mm for DN1000), reducing deformation during bolt tightening. It complies with EN558-1 Series 20 face-to-face dimensions for strong installation compatibility.
Low-Torque Operation:
The worm gear reducer (ratio 1:30-1:60) uses a bronze worm wheel + 45# steel worm shaft, surface carburized (hardness HRC55-60). Manual operation torque for DN1000 ≤150N·m, electric actuator full-stroke time ≤20s, adapting to rapid response needs of automation systems.
(C) Material System & Application Adaptability
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Component
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Material
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Performance Indicators
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Body
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Ductile Iron QT450-10
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Tensile strength ≥450MPa, impact energy ≥27J at -20°C
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Disc
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Ductile Iron/304 SS
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Surface roughness Ra≤3.2μm, erosion resistance +30%
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Seat
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EPDM/NBR Rubber
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Temperature -20°C~120°C, chloride ion corrosion resistant
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Stem
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2Cr13 Stainless Steel
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Trapezoidal thread accuracy 6g, quenched & tempered HB220-250
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III. Key Technical Parameters
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Parameter Category
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Technical Indicators
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Expansion Options
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Nominal Size
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DN300-DN2400 (12″-96″)
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Custom DN2600-DN3000 (engineering evaluation)
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Pressure Rating
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PN10-PN16 (1.0-1.6MPa)
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High-pressure PN25 (2.5MPa)
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Connection Type
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Double Flange (EN1092)
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Butt weld, socket weld (ASME B16.25)
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Actuation
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Manual Worm Gear/Electric/Pneumatic
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Hydraulic actuator, explosion-proof (Ex d IIC T6)
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Sealing Standard
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EN12266 Class A/B
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Fire certification API 607 (metallic seal redundancy)
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Testing Standard
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API 598, EN12266
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Low-temperature testing (-40°C, requires material upgrade)
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Product Overview
IV. Manufacturing Processes & Quality Control
(A) Precision Manufacturing Flow
Body Casting & Machining:
Ductile iron bodies use lost foam casting, annealed at high temperature to relieve stress, with graphite spheroidization rate ≥90%. 100% ultrasonic testing (UT) after machining, surface roughness Ra≤12.5μm.
Flange surfaces are machined by CNC gantry milling, flatness error ≤0.05mm, bolt hole spacing deviation ≤±0.3mm to ensure installation tightness.
Disc & Seat Assembly:
The disc undergoes dynamic balance testing (residual unbalance ≤5g·cm). Rubber seats are molded under pressure, with interference fit clearance ≤0.02mm to the body. Each valve undergoes 1.5x nominal pressure hydrostatic test (30-min hold) and 1.1x air pressure test (helium leak detection).
Drive System Debugging:
Worm gear meshing clearance controlled at 0.05-0.1mm. Electric actuators undergo 100 no-load cycle tests, positioning accuracy ±1%, torque overload protection set at 1.2x rated value.
(B) Quality Certification System
Material Traceability: Key components come with heat numbers and CMA-certified chemical reports, supporting third-party PMI testing.
System Certifications: Holds ISO 9001, CE-PED; drinking water products comply with WRAS; marine models can provide DNV-GL, LR classification certifications.
After-Sales Guarantee: 18-month warranty, free replacement for leakage due to process issues, lifelong maintenance technical support.
