A Brief Introduction to the Basic Knowledge of Flanged Butterfly Valve

2025-11-05

In industrial fluid control, Butterfly Valves play a key role in adjusting, guiding and shutting off the flow of liquids, gases and slurries inside pipeline systems. The flange-type butterfly valve is a common connection design. It hasintegral flanges on both ends of its body, which can be firmly connected to pipeline flanges with bolts.

Definition

A Flange Butterfly Valve is a quarter-turn valve type. Its operation involves a disc that controls fluid flow by rotating with the valve stem. The valve body features flanges at both ends, allowing direct connection to pipeline flanges using bolts.These valves employ raised or flat face flanges with bolt holes, ensuring a secure and stable joint in the piping system.

Operating Principle

This valve works on a simple and efficient principle. Whether you turn the stem manually with a handle or gear, or use an automatic actuator to drive it, the disc moves along—rotating from a fully open position parallel to the flow direction to a fully closed position perpendicular to it.

When fully open, the disc lines up with the pipeline axis, which keeps flow resistance and pressure drop as low as possible. In the closed position, the disc presses tightly against the seat inside the valve body to create a reliable seal.

Component

Body: It's the valve's outer shell, with a double-flange design. This design not only enables pipeline connection but also supports the internal parts. For materials, ductile iron is used for regular cases; stainless steel is chosen for corrosive media; nickel-aluminum bronze works for marine use; and alloy steel is applied in extreme conditions.

Disc: This rotating part controls fluid flow, and it comes in two designs: streamlined and flat. Its materials cover a wide range, including ductile iron, stainless steel, aluminum bronze, and nylon-coated types—these nylon-coated ones offer better wear resistance.

Stem: It's the shaft that connects the disc and actuator, and its job is to transfer rotational force. Usually made of stainless steel, aluminum bronze, or high-strength alloys, it has two designs: through-shaft and non-through-shaft.

Seat: This is the sealing surface, made of elastomeric materials. Common options are EPDM, NBR, and VITON—these materials are also used for the valve's rubber lining.

Actuator: As the driving mechanism, it has two operation modes. One is manual, using a handle or gear operator; the other is powered, like pneumatic or electric actuators.

Packing & Gaskets: Their main role is sealing—they ensure effective sealing at the stem and flange connections, keeping the space between components leak-proof.

Industry Applications

Water & Wastewater Treatment: Regulate flow efficiently in treatment plants and diversion systems.

Oil & Gas Applications: Serve pipelines for crude oil, natural gas transportation, and refining processes.

Power Generation Systems: Manage steam, cooling water, and fuel supply reliably.

Food & Beverage Production: Meet hygienic standards and handle sterile fluids safely.

Pharmaceutical Industry: Enable precise control in strictly sterile environments.

Marine & Paper Manufacturing: Be used in seawater treatment, pulp processing, and related chemical processes.

Advantages and Disadvantages

Advantages

Compact and lightweight design: Cuts down on installation costs and space needed.
Quick 90-degree operation: Enables fast opening and closing for immediate response.
Cost benefits at larger sizes: Becomes more economical with increasing diameter.
Minimal pressure drop when open: Promotes energy savings and operational efficiency.
Ideal for flow switching, seals tightly: Excellent sealing makes it reliable for directing fluids.
Easy to maintain and automate: Simple upkeep and ready for automated system integration.

Disadvantages

Flow obstruction, pressure loss: The valve disc partially blocks the passage even when open, resulting in a measurable pressure drop.
Limited throttling, cavitation risk: Its capacity for flow control is restricted under high pressure, which can lead to cavitation.
High starting torque, powerful actuator needed: Some designs require substantial initial torque, necessitating the use of a more robust actuator.

Installation Guide

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Align holes, insert gasket, tighten evenly: Position the valve flange to match the pipeline flange, ensuring bolt holes align. Insert the sealing gasket and secure with bolts and nuts, tightening evenly to avoid distortion.

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Double-flange: simultaneous alignment; Lug-type: side-by-side: Install double-flange valves by aligning both sides at once, whereas lug-style valves can be fixed one side at a time.

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Cycle valve before pressurization: Perform several open-close cycles before system pressure is applied to verify the disc moves freely through its full range.

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Horizontal stem for vertical installation: When mounting vertically, always position the valve stem horizontally to prevent sediment accumulation.