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Lined Butterfly Valve

Updated: 2026-07-17

Overview

A lined butterfly valve is a quarter-turn rotational motion valve used to regulate or isolate fluid flow in pipelines. Its defining characteristic is a corrosion-resistant lining (e.g., PTFE, EPDM, or natural rubber) bonded to the valve body and disc, protecting metallic components from aggressive media. This design combines the simplicity of a butterfly valve with enhanced chemical resistance, making it a cost-effective solution for handling acids, alkalis, slurries, and other challenging fluids. Lined butterfly valves are widely adopted in industries such as chemical processing, pharmaceuticals, water treatment, and mining due to their compact footprint, low maintenance requirements, and reliable sealing performance. They are available in wafer, lug, or flanged end connections to suit different piping systems.

Structure and Working Principle

The valve consists of a circular body, a rotating disc (the "butterfly"), a stem, and an elastomeric or polymer lining. When the handle or actuator rotates the stem by 90 degrees, the disc moves from a parallel (open) to a perpendicular (closed) position relative to the flow. The lining ensures a tight seal against the disc while resisting chemical attack. Key structural variants include concentric (zero-offset) and double-/triple-offset designs, with the latter reducing wear by minimizing contact between the disc and lining during operation. High-performance lined butterfly valves often incorporate fire-safe designs and metal-seated options for extreme conditions.

Key Features

1. **Corrosion Resistance**: The lining material (e.g., PTFE for broad chemical resistance, rubber for abrasion resistance) shields the valve body from corrosive fluids, extending service life. 2. **Bubble-Tight Sealing**: Resilient linings provide excellent shutoff, with leakage rates meeting ANSI/FCI 70-2 Class VI standards. 3. **Low Torque Requirement**: The lightweight disc design reduces actuation force, enabling smaller, more economical actuators. 4. **Bi-Directional Flow**: Suitable for flow in either direction, though some high-performance designs may have preferred flow orientations. These valves are also praised for their quick operation, minimal pressure drop, and suitability for large diameters (up to 60 inches or more).

Application Areas

Lined butterfly valves are indispensable in industries handling aggressive fluids: - **Chemical Processing**: For acids, alkalis, and solvents in reactors, storage tanks, and transfer lines. - **Water/Wastewater Treatment**: Chlorine, ozone, and slurry handling in filtration and disinfection systems. - **Mining and Metallurgy**: Abrasive slurry control in tailings and leaching processes. - **Pharmaceuticals**: Sterile fluid handling where contamination risk must be minimized. They are less suitable for high-temperature steam or hydrocarbon services, where metal-seated valves are preferred.

Maintenance and Precautions

Routine maintenance includes inspecting the lining for cracks, erosion, or delamination, and lubricating the stem if applicable. Avoid: - Exceeding the lining’s temperature limit (typically -20°C to 180°C for PTFE). - Using the valve for throttling abrasive fluids unless designed for such service. - Over-tightening flange bolts, which can distort the lining. For storage, keep valves in a dry environment with the disc slightly open to prevent lining compression set. Actuators should be periodically checked for proper torque output.

B2B Procurement Guide

When sourcing lined butterfly valves, specify: 1. **Fluid Compatibility**: Match lining material (PTFE, EPDM, FKM, etc.) to chemical exposure. 2. **Pressure/Temperature Ratings**: Ensure compliance with system requirements (e.g., ANSI 150 or 300). 3. **End Connections**: Wafer-style valves are economical but require piping alignment; lug or flanged types allow easier removal. 4. **Standards**: Look for certifications like ISO 9001, API 609, or TA-Luft for critical applications. Leading manufacturers include DeZURIK, Bray, and GEA. Bulk procurement (10+ units) may qualify for 10–15% discounts.

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