What is a Butterfly Valve: Detailed Applicable Instructions

What is a Butterfly Valve

A butterfly valve is a quarter-turn valve featuring a rotating disc (butterfly plate) attached to a central stem. This compact design enables quick flow control or isolation in pipelines. Widely used across industries, butterfly valves excel in applications requiring cost-effective, lightweight solutions with low-pressure drop.

 

Butterfly Valve Structure: 4 Key Components


1. Valve Body: Cylindrical housing (cast iron, stainless steel, or ductile iron) with flanged/lug/weld ends.

2. Valve Disc: Rotating plate controlling flow – available in concentric, double/triple eccentric configurations.

3. Stem: Connects actuator to disc for torque transmission.

4. Seat: Sealing surface (soft rubber, PTFE, or metal) ensuring leak-tight closure.

What is a triple eccentric butterfly valve - assembly diagram

 

How Do Butterfly Valves Work

The disc rotates 90° between:

- Fully Open: Disc aligns parallel to flow (minimal pressure loss)

- Fully Closed: Disc blocks flow perpendicular to the pipe

 

Types of Butterfly Valves

By End Connection Type

- Wafer Butterfly Valve: Flangeless design clamped between pipe flanges

- Lug Butterfly Valve: Threaded inserts for easy pipeline disconnection

- Flange Butterfly Valve: Integrated flanges for bolt-to-bolt mating

- Welded Butterfly Valve: Permanent welded connection for high-integrity systems

 

By Design

1. Concentric (Centerline) Butterfly Valve

– Disc/stem centered in valve bore

– Budget-friendly for low-pressure water systems

2. Double Eccentric (High-Performance) Butterfly Valve

– Offset stem reduces seat wear

– Handles higher pressures up to 1,480 psi

3. Triple Eccentric Butterfly Valve

– Three offsets (stem, disc, seat angle)

– Metal-seated solution for extreme temps (up to 1,022°F)

What is a triple eccentric butterfly valve - structural principle diagram

 

By Actuation

- Manual Butterfly Valve: Hand lever/gear operator

- Pneumatic Butterfly Valve: Air-powered pneumatic actuator for rapid cycling

- Electric Butterfly Valve: Motorized control for automation

- Hydraulic Butterfly Valve: Oil-pressure driven for high-torque needs

 

Butterfly Valve Applications

| Industry | Use Case | Recommended Type |
|———-|———-|——————|
| Water Treatment | Pump isolation | Rubber-lined concentric |
| Oil & Gas | Crude pipelines | Triple eccentric metal-seated |
| HVAC | Chilled water | Lug-style with EPDM seat |
| Food Processing | CIP systems | Sanitary clamp butterfly valve |

 

Installation & Maintenance Guide

5 Critical Installation Steps

1. Flange Alignment: Ensure pipe flanges are parallel within 0.8mm

2. Gasket Selection: Use PTFE/spiral-wound gaskets for thermal cycles

3. Bolt Tightening: Follow cross-pattern sequence (30-70-100% torque stages)

4. Actuator Orientation: Keep stem horizontal for optimal seal life

5. Post-Install Test: Perform 1.5x pressure test with disc at 10° open

Pro Tip: Always cycle new valves 5-10 times under pressure to seat seals properly.

 

Maintenance Checklist

- Monthly: Inspect stem packing for leaks

- Quarterly: Lubricate stem bushings with food-grade grease (if applicable)

- Annually: Perform seat leakage test per API 598 standards

 

Need Expert Butterfly Valve Selection

Newsway Valve Manufacturer provides ISO 9001-certified butterfly valves with 10-year seat warranties. Contact our engineers for a free application review.


Post time: Mar-29-2025