A large-diameter butterfly valve is a quarter-turn rotary valve typically defined as having a nominal diameter (DN) ≥ 600 mm (DN600, DN800, DN1000, DN1200, DN1400, DN2000 and above).It consists of a body, a circular disc, a stem, a seat seal, and an actuator. The disc rotates 0°–90° around the stem to shut off, throttle, or regulate flow in large-volume pipelines.

Key characteristics:

Compact structure, light weight, small installation space;

Low flow resistance, fast opening and closing;

Suitable for large flow rates and low-to-medium pressure systems;

Widely used in water supply, wastewater, hydraulics, power plants, and petrochemical systems.

Main Types of Large-Diameter Butterfly Valve

(1) By Sealing Structure

Soft-sealed butterfly valve

Seat: EPDM, NBR, PTFE, etc.

Features: bubble-tight leakage, low pressure, normal temperature

Application: water, sewage, clean gas.

Hard-sealed butterfly valve

Seat: metal-to-metal, stellite alloy

Features: high temperature resistance, high pressure resistance, wear resistance

Application: steam, high-temperature oil, gas, abrasive media.

(2) By Eccentric Design

Center (Concentric) butterfly valve

Simple structure, low cost; used for low-pressure, non-critical systems.

Double eccentric butterfly valve

Stem offset from center and body axis; reduces friction, improves sealing.

Triple eccentric butterfly valve

Based on double eccentricity plus a conical sealing surface;achieves zero leakage under high pressure and temperature;the most common type for high-performance large-diameter applications.

(3) By Connection

Flanged

Lug type

Wafer type

Double flange (for large pressure pipelines)

Operating Conditions

Large-diameter butterfly valve are generally designed for:

Pressure class: PN6, PN10, PN16, PN25 (mostly low to medium pressure)

Temperature range:

Soft seal: −20 °C ~ +120 °C

Hard seal: up to 450 °C or higher

Media:Water (raw water, circulating water, sewage), air, gas, oil, weak corrosive liquids

Flow mode: On-off control or flow regulation

Environment: Outdoor, buried, pump stations, water diversion projects, coastal and industrial environments

Selection Tips

Determine diameter

Match pipeline nominal diameter (DN600 and above).

Pressure and temperature

Low pressure & normal temperature → soft-sealed concentric or double-eccentric

High pressure & high temperature → triple-eccentric hard-sealed

Leakage requirement

Tight shutoff → triple eccentric or soft-sealed with zero-leakage seat.

Medium properties

Clean water → EPDM soft seal

Abrasive / high-temperature → metal hard seal

Operation frequency

Frequent switching → eccentric structure to reduce wear.

Installation space

Limited space → wafer or lug butterfly valve

High stability requirement → flanged type

Actuator selection

Manual: small diameter, infrequent operation

Electric / pneumatic / hydraulic: automatic control, large diameter

Actuation / Driving Methods

Manual operation

Hand lever, worm gear; for small loads and infrequent use.

Electric actuator

Electric motor + gearbox; remote control, automatic regulation; most widely used for large diameter.

Pneumatic actuator

Piston or diaphragm type; fast action, suitable for explosion-proof areas.

Hydraulic actuator

High torque, stable performance; for ultra-large diameter and high-pressure systems.

Maintenance and Repair Methods

(1) Routine Maintenance

Regularly check for external leakage at flange and stem packing.

Lubricate stem and gearbox periodically.

Monitor operating torque; abnormal torque indicates wear or seizure.

Keep the actuator clean and dry; protect electrical parts from moisture.

(2) Periodic Overhaul

Inspect disc and seat for wear, scratch, or deformation.

Replace aged gaskets, O-rings, and packing.

Check concentricity and alignment of the stem.

Clean scale, sediment, and debris inside the valve body.

(3) Common Fault Solutions

Leakage at seat → replace seal ring or adjust torque.

Stem leakage → tighten or replace packing.

Difficult operation → clean debris, add lubricant, repair eccentricity.

Abnormal noise → check disc vibration, loose fasteners.

(4) Long-term Storage

Store in dry, ventilated environment.

Keep disc slightly open to avoid seat compression deformation.

Protect flanges and machined surfaces from corrosion.

Tags: Large-Diameter Butterfly Valve