Specification

DN800 CF8 Stainless Steel Triple Eccentric Hard-Sealed Butterfly Valve

I. Product Overview

TIANYU DN800 triple eccentric hard-sealed butterfly valve is a specialized flow control solution engineered for large-diameter water media pipelines. Crafted with CF8 stainless steel—renowned for corrosion resistance—it features a triple eccentric structure, rotary disc, and worm gear drive to balance precise shut-off and long-term reliability. Operating at PN10~PN16 pressure and normal temperature, it leverages the triple eccentric design to minimize disc-seat contact during operation, reducing wear. Compliant with international standards, it is ideal for water supply, wastewater treatment, and industrial water systems where corrosion resistance, large flow capacity, and sealing stability are critical.

II. Key Attribute Parameters

Size: DN800, tailored for large-diameter water pipelines requiring high flow throughput.
Pressure Range: PN10~PN16 (1.0MPa~1.6MPa), adapting to low to medium-pressure water systems such as municipal water networks and industrial water circulation loops.
Temperature Range: Normal temperature (-10℃~80℃), suitable for cold/hot water and non-corrosive water-based media.
Material Configuration:
- Body & Disc: CF8 stainless steel, offering excellent corrosion resistance to water, humidity, and mild impurities—avoiding rust-related blockages.
- Sealing Pair: Hard-sealed (disc with Stellite coating, seat with alloy surfacing), ensuring tight shut-off and wear resistance under frequent operation.
- Worm Gear & Stem: Forged alloy steel and stainless steel, with anti-jamming design for smooth rotation.
- End Connections: Flanged (per GB/DIN/ANSI standards), enabling leak-tight integration with large water pipelines.
Actuation: Worm gear drive, reducing operating torque to enable manual control of DN800 valves without excessive force.
Design Standards: Adopts triple eccentric structure (axis, disc, seat eccentricity) to minimize friction; tested to meet industrial sealing and pressure resistance norms.

Product Overview

III. Features Description

Triple Eccentric Structure: The valve integrates three eccentric offsets to ensure the disc only contacts the seat at full closure—avoiding friction during opening/closing. This eliminates seal wear from media scouring, a common issue in concentric valves, and ensures the seal tightens under pressure for zero leakage.
CF8 Corrosion Resistance: CF8 stainless steel (18% Cr, 8% Ni) forms a passive oxide layer, resisting rust and pitting from water, sediment, and mild chemicals. This outperforms carbon steel in humid or long-term water immersion environments, maintaining structural integrity for decades.
Hard-Sealed Reliability: Stellite-coated disc (hardness ≥HRC55) and alloy seat form a metal-to-metal seal, withstanding sediment-laden water without seal damage. Unlike soft seals, it avoids aging or deformation, ensuring consistent performance in outdoor or unheated pipelines.
Worm Gear Efficiency: The worm gear drive reduces operating torque by 60% compared to direct manual operation, allowing one person to easily control DN800 valves. Its self-locking function prevents accidental rotation from pipeline vibration, critical for large water networks.
Large Flow Capacity: The rotary disc (90° rotation) creates minimal flow resistance when fully open, with a flow coefficient (Cv) 30% higher than gate valves of the same diameter—ideal for water transmission where energy efficiency is key.

IV. Manufacturing Processes

Material Validation: CF8 stainless steel undergoes spectral analysis to verify alloy content and ultrasonic testing to detect internal defects. Stellite powder for sealing surfaces is inspected for purity to ensure wear resistance.
Precision Machining: Body and disc are CNC-machined to tight tolerances (±0.05mm). The disc’s sealing surface is ground to Ra ≤1.6μm, then coated with Stellite via plasma welding to 0.5~1mm thickness, followed by precision grinding.
Eccentric Calibration: The triple eccentric parameters are calibrated using 3D measurement to ensure the disc aligns with the seat only at full closure. Worm gear meshing is adjusted to 0.1~0.2mm clearance for smooth rotation.
Assembly & Testing:
- Components are assembled with torque-controlled fasteners, with the stem sealed via O-rings to prevent water ingress into the gearbox.
- Hydrostatic Test: Body tested at 1.5×PN (2.4MPa for PN16) for 30 minutes; seat tested at 1.1×PN with water to confirm no leakage.
- Operation Test: 50+ open/close cycles to verify worm gear smoothness and disc positioning accuracy.

Valve Details

V. Product Advantages

Zero Leakage in Water Systems: Triple eccentric and hard-sealed design eliminate leakage, reducing water loss by 99% compared to standard valves—critical for municipal water networks where efficiency is regulated.
Long Service Life: CF8 corrosion resistance and Stellite wear resistance extend service life to 15~20 years, reducing replacement costs in large-diameter pipeline projects.
Energy & Cost Savings: Low flow resistance cuts pump energy consumption by 10~15% in water transmission. Worm gear operation avoids the need for expensive actuators in manual systems.
Maintenance Convenience: Flanged connection allows in-line inspection; worm gear components are modular for easy replacement, minimizing downtime in critical water supply.
Environmental Adaptability: Resists rust, UV damage, and temperature fluctuations, adapting to outdoor, underground, or industrial water pipelines without performance degradation.

Application

VI. Application Fields

Municipal Water Supply: Controls flow in large-diameter water mains, with corrosion resistance adapting to long-term underground installation and tight sealing preventing water loss.
Wastewater Treatment: Regulates flow in secondary treatment and discharge lines, with hard seals resisting abrasion from sludge and CF8 material withstanding mild chemical cleaners.
Industrial Circulation: Manages cooling water flow in power plants or factories, leveraging large flow capacity to meet high-demand systems and avoid pressure drops.
Irrigation Projects: Controls water distribution in agricultural canals, with weather-resistant design adapting to outdoor conditions and reliable sealing preventing water waste.

TIANYU DN800 butterfly valve: CF8 stainless steel, triple eccentric, PN10~16. Worm gear, hard-sealed. Resists corrosion, zero leakage. Ideal for water supply, wastewater. Customizable: flange (DIN/ANSI), coating for extreme water conditions.