Lugs Vs. Wafer-Type: Structural Differences And Selection Guide For Stainless Steel Butterfly Valves

In the field of industrial fluid control, stainless steel butterfly valves has become core equipment of petroleum, chemical industry industry, electric power and water treatment industry because of its corrosion resistance, light weight and fast opening and closing speed. steel butterfly valves is divided into two main types according to the connection mode: camtype and wafer type. In this paper, the technical differences and selection logic of these two types are analyzed systematically from four dimensions: structural characteristics, performance differences, application scenarios and selection principles.
I. Structural differences: from connectivity Methodss to core design
1.Cam butterfly valve: stable connection and Modular Design
The lug butterfly valve has a lug structure extending from both ends of the valve body and is bolted directly to the pipeline flange. The design gives it three core advantages:
Installation stability: lugs and flanges rigidly connected, can withstand high pressure impact. For example, in a catalytic cracking unit at a refinery, the CLAS the CLASS 300 hard-seal lug-type butterfly valve is used to control a crude oil transportation pipeline, withstand pressure of 7.5 MPa and operate leak-free for 5 years.
Modular maintenance: lug design allows for rapid dismantling without damaging piping system and is therefore particularly suitable for space-constrained situations such as ship fuel pipelines and cooling water systems for nuclear power plants.
Two-way seal: Some models have a three-seal structure (two soft seals + one metal seal) that keeps leaks free even at high temperatures and pressures. For example, valves used in chemical plants to transport concentrated sulfuric acid have operated continuously for three years without corrosion leakage.
2.Wafer Butterfly: Lightweight and Space Optimization
The wafer Wafer butterfly valves is sandwiched directly between the flanges at both ends of the pipe and requires no additional support structure. Its design features include:
Space efficiency: Installation space is 40% smaller than flanged valves, suitable for cramped or high altitude operations. For example, the Xiong'an New Area Smart Water Project uses DN1200 wafer butterfly valve to achieve zoned pressure control, saving 2 million tons of water per year.
Cost Advantage: Simplified structure, 30% reduction in material costs, but limited corrosion resistance and temperature resistance, more suitable for low voltage, non-corrosive media (e.g. air-conditioning cooling water systems). Bidirectional flow: Installation is not limited by the direction of the medium flow and can be installed in any direction. Leakage rate is GB/T13927-92 standard (zero leakage or level 5 leakage).
ii. Performance Comparison: from seal to durability
1.Sealing Performance
Lumbered Lug Type: Triple sealing structure (such as triple ethylene propylene rubber soft seal + metal hard seal) is excellent at high temperature and pressure. For example, the use of electric lug butterfly valves in cooling pipes at power plants system energy consumption consumption by 15% and results in zero leakage.
Waist-Type: Soft sealing type (such as PTFE) suitable for low temperature and pressure environment. Hard seals (e.g. metal-to-metal) are resistant to high temperature (≤650°C) and high pressure (≤6.4MPa), but their high temperature sealing performance is slightly lower than this lug type.
2. Corrosion Resistance
Lumbered Lug Type: 316L stainless steel or duplex steel, chlorine-resistant. For example, valves made of 316L material used in coastal chemical parks are resistant to salt spray corrosion and have a service life of more than 15 years.
Wafer type: 304 stainless steel for general working conditions. For highly corrosive media, polytetrafluoroethylene (a PTFE-lined structure) is required, but this increases costs.
3. Opening and Closing Characteristics
Lumber type: some models are double or triple eccentricity, opening and closing torque reduced by 60%, service life extended to more than 5 years. For example, in a catalytic cracking unit at a refinery, when an electric butterfly valve replaces a gate valves valve, the opening and closing time reduced from 5 minutes to 10 seconds.
Wafer type: Centerline butterfly plates flow resistance is small, pressure drop is only 1/3 of the same diameter gate valve full opening state. However, under high frequency operation, graphite bearings requires less wear and tear.
III. Application Scenarios: From Extreme Conditions to Intelligent Control
1. Lug Type Butterfly Valve
High-end industries: petrochemicals (FCC feed control), electricity (supercritical unit main steam pipeline regulation), metallurgy (blast furnace gas pipeline closure). Extreme operating conditions: cooling water systems for nuclear power plants (radiation resistance), deep-sea oil and gas pipelines (high pressure resistance up to 15MPa), liquefied natural gas transportation systems (low temperature resistance down to -196°C).
Intelligent control: Integrated electric actuator with support for 4-20mA signal input or 1-5VDC voltage control with response time <50ms and positional accuracy ±1%.
2. Wafer-type butterfly valve
Civil and environmental applications: municipal water supply (high-flow regulation of major pipelines), sewage treatment (sulfide corrosion resistance aeration pipelines), building materials production (continuous control of cement kiln tailpipes).
Low temperature conditions: LNG transport system (low-temperature brittleness, temperature range expanded to -196°C).
Economical applications: Air-conditioning cooling water system (DN100 specification price about $400, 20 percent off). IV. INTRODUCTION INTRODUCTION Selection Guide: four core principles
1. Choose according to pressure and temperature
High pressure systems (>4.0MPa): lugs preferred for structural stability; seal structure are required for ultra-high temperature environments (>300°C).
Low pressure conditions (less than 1.0MPa): Wafer type is more cost-effective, but the temperature resistance of the sealing material must be confirmed (e.g. EPDM is suitable ≤ 150°C).
2. Material Selection based on Media Characteristics
Highly Corrosive Media: Lug type, sealed with 316L stainless steel + PTFE; wafer with a fluoropolymer-lined structure (e.g., PTFE lining).
Particulate Media: lug type hard seal valve with cobalt base alloy coating; wafer type hard seal valve with wear-resistant seat (e.g. tungsten chromium cobalt alloy).
3. Selection based on Space and Maintenance Requirements
Space limitation scheme: easy installation of the Wafer type, but flange spacing must remain the same; lug type is suitable for terminal valve installation.
High frequency maintenance program: lug modular design, easy to seal replacement; wafer type requires complete disassembly.
4. Intelligent needs-based
Remote monitoring: select an electric lug butterfly valve with 5G integrated IoT module (such as Shanghai Qizhong products).
Explosion-proof environment: Pneumatic wafer actuators must be ATEX certified (e.g., ExdIICT6).
V. Typical Cases: from theory to practice
Case 1: FCC units at oil refinery
The 300 hard-sealed lug butterfly valve in the crude pipeline have a pressure resistance of 7.5MPa, reduce opening and closing time from 5 minutes to 10 seconds, and reduce annual maintenance costs by 40%.
Case 2: Xiong'an New Area Smart Water Project
DN 1200 electric disc butterfly valve is used to realize zoned pressure control, reduce leakage rate by 62% and save 2 million tons of water annually.
Case 3: Coastal Chemical Industrial Park
316L lug butterfly valve is salt mist-resistant and has a service life of more than 15 years, three times that of a carbon steel valve bodies.
Taken together, lug stainless steel butterfly valve and steel butterfly have their own unique advantages: lug stainless steel butterfly valve has the advantages of connection stability, high voltage resistance, modular maintenance, and so on, suitable for extreme working conditions and high-end industries; thyristor stainless steel butterfly valve focuses on the design of lightweight, low-cost, space optimization, in civil and economical fields dominant. When selecting valve, we should take into account pressure, temperature, medium, space and intelligent requirements to achieve efficient and reliable fluid control through the three-dimensional matching of material-structure-control.