Posted on: CNLD VALVE Official News
Butterfly valves are widely recognized for their compact structure, easy operation, and excellent flow control capabilities. Their light weight, low flow resistance, and cost-effectiveness make them a popular choice in many industrial piping systems. However, improper selection can lead to leakage, seal failure, and even safety risks. At CNLD VALVE (ZHEJIANG LED VALVE), we’ve summarized the essential selection principles and suitable applications to help you make the right decision.
1.1 Choose the Sealing Pair Based on Medium Characteristics
Clean, non‑corrosive or mildly corrosive media (water, air, mineral oil) → Soft‑sealed butterfly valves with linings such as NBR (≤90°C) or EPDM (≤120°C), or PTFE (≤230°C, short‑term up to 260°C). These offer excellent sealing and moderate cost.
High‑temperature steam (≥250°C), hot oil, or strong corrosive chemicals (acids, alkalis, oxidizers) → Metal‑sealed butterfly valves. We recommend hardfacing with Stellite, Hastelloy, or other wear‑/corrosion‑resistant alloys.
WCB body: ≤425°C
Alloy steel (WC6, WC9, CF8C): up to 600°C
Above 600°C: use Inconel or nickel‑based alloys with special graphite sealing.
Media containing solid particles or fibers (wastewater, pulp, slurry) → Eccentric butterfly valves (double or triple offset) to avoid particle jamming or seal scratching. Match with wear‑resistant sealing pairs.
1.2 Select Valve Body Material by Pressure & Temperature
Low pressure (≤1.6MPa) & ≤80°C → Gray cast iron (HT200) or ductile iron (QT450‑10) – ideal for water supply and low‑pressure air lines.
Medium pressure (≤4.0MPa) & ≤250°C → WCB cast steel or stainless steel (304/316L). Always verify liner compatibility (PTFE, rubber) with the medium.
High pressure (>4.0MPa) & DN ≥150 → Double‑offset or triple‑offset butterfly valves.
Note: When DN >400 and pressure >4.0MPa, butterfly valves are less reliable than gate or ball valves – evaluate carefully.
Frequent on‑off cycles → Prefer double/triple offset designs for lower seal wear and reduced torque.
1.3 Choose Structure Based on Flow Control Needs
On‑off only → Concentric (center‑line) butterfly valve: low cost, easy installation.
Throttling / flow regulation → Double or triple offset butterfly valves (near‑equal percentage characteristic).
If regulation accuracy ≤ ±5% is required, use a control valve or ball valve instead.
Concentric butterfly valves are not recommended for regulation due to high sealing pressure, distorted flow characteristics at 30–70° opening, and rapid rubber fatigue.
1.4 Consider Installation & Maintenance
Wafer type → Compact, lightweight, space‑saving. But requires loosening both flanges for disassembly – suitable for infrequent maintenance.
Lug / flanged type → Easy to remove and reinstall – the most widely used design for industrial sites.
Welded type → Only for high‑pressure or zero‑leakage special conditions. Once installed, replacement is difficult.
Note: Welded butterfly valves are rarely used in extreme services like main steam lines – gate or globe valves are preferred.
I Water & wastewater treatment : Concentric soft‑sealed valves for raw water, aeration, sludge discharge, and circulation systems.
HVA:Butterfly valves with handwheel, worm gear, or electric actuator for cooling/chilled water mains.
Chemical & pharmaceutical :PTFE or PFA lined corrosion‑resistant valves – smooth bore, no stagnant zones, easy to clean.
Food & beverage: Sanitary stainless steel polished butterfly valves with tri‑clamp connections, suitable for CIP/SIP.
Metallurgy & power:Triple‑offset metal‑sealed valves for circulating water, desulfurization, and high‑temperature flue gas.
Marine & offshore :Salt‑spray resistant, anti‑vibration designs – bronze or duplex stainless steel (e.g., 2205).
Final Thoughts
Selecting the right butterfly valve is not a fixed formula. You must understand the actual operating conditions: medium characteristics, working pressure, temperature, seal compatibility, installation space, and maintenance frequency.
At CNLD VALVE (ZHEJIANG LED VALVE), we offer a full range of butterfly valves – from economic soft‑sealed types to high‑performance triple‑offset metal‑sealed models – tailored to your application. Contact our engineering team to ensure safe, reliable, and efficient operation of your pipeline system.
For more technical insights, stay tuned to the CNLD VALVE news blog.
