Selecting the right industrial butterfly valve involves more than just specifying body materials and disk dimensions. One of the most critical engineering decisions is choosing the correct end connection type. The connection design determines how the valve integrates into the piping system, how easy it is to install or replace, and whether it can handle specific operational conditions such as dead-end service.
The three primary connection styles for industrial butterfly valves are Wafer, Schleppen, Und Mit Flansch (Double Flanged). As an established China industrial valve manufacturer, TWT Valve breaks down the differences, Vorteile, and ideal applications for each connection type to help you select the best hardware for your piping infrastructure.
1. Absperrklappen vom Zwischenflanschtyp: Compact & Economic
Structural Design
A wafer butterfly valve features a compact, flat body designed to be sandwiched between two pipe flanges. Long bolts (studs) pass through the entire pipe flange assembly and encase the valve body.
Key Characteristics
- Ultra-Compact Footprint: Short face-to-face dimensions save space in tight mechanical rooms or pumping stations.
- Lightweight & Kosteneffizient: Minimal body material reduces both valve weight and transport costs, making it lower in cost compared to flanged alternatives.
- Limitations: Wafer valves cannot be used in dead-end service (where one side of the pipe is disconnected for maintenance while the other remains under pressure), because removing the downstream flange bolts releases the valve entirely.
2. Absperrklappen vom Ansatztyp: Versatile for Dead-End Service
Structural Design
A lug butterfly valve features threaded metal inserts (lugs) protruding outward around the perimeter of the valve body. Bolt holes match the bolt pattern of the connecting pipe flanges.
Key Characteristics
- Independent Bolting: Instead of through-bolts, short bolts thread into the valve body from both sides.
- Dead-End Service Capability: Because each flange is bolted independently to the valve body, the downstream piping can be disconnected without relieving line pressure on the upstream side. This is essential for pump station maintenance and tank isolation.
- Moderate Weight: Heavier than wafer types due to the extra metal lugs, but still lighter than double flanged bodies.
3. Mit Flansch (Double Flanged) Butterfly Valves: Maximum Heavy-Duty Stability
Structural Design
A Doppelflansch-Absperrklappe features complete integral flanges at both ends of the valve body, designed to mate directly with matching pipe flanges using standard nut-and-bolt sets.
Key Characteristics
- High Structural Integrity: Flanged connections handle line stress, thermal expansion, and bending moments far better than wafer or lug valves.
- Ideal for Large Diameters: Highly recommended for large-diameter pipelines (DN300–DN3000) and underground municipal water mains.
- Superior Gasket Sealing: Provides robust sealing surfaces for high-pressure lines (PN16, PN25, Klasse 150/300).
Side-by-Side Comparison: Wafer vs. Lug vs. Mit Flansch
| Feature / Metric | Wafer-Absperrklappe | Lug-Absperrklappe | Double Flanged Butterfly Valve |
| Bolting Method | Long studs pass through both pipe flanges | Short bolts thread directly into body lugs | Bolted directly flange-to-flange |
| Dead-End Service | NEIN | Ja | Ja |
| Weight & Kosten | Lightest / Lowest Cost | Moderate | Heavy / Highest Structural Rigidity |
| Space Required | Minimal face-to-face | Moderate face-to-face | Longer face-to-face dimension |
| Best For | Space-constrained pipelines, general utilities | Pump outlets, line isolation, maintenance nodes | Large-diameter water mains, high-pressure lines |
To explore detailed technical datasheets and flange drilling options across all connection styles, browse our full industrial valve products catalog.
How to Choose the Right Connection Type for Your Project
- Choose Wafer Valves when pipeline installation space and budget are primary constraints, and the line will not require single-side disconnection during operation.
- Choose Lug Valves when you need isolated downstream maintenance capability, dead-end service at pipe terminals, or reliable pump discharge isolation.
- Choose Double Flanged Valves for high-pressure surge lines, large-diameter buried pipelines, or critical infrastructure where structural integrity is paramount.
Custom Engineering Solutions at TWT Valve
Whether your project calls for resilient seated wafer butterfly valves, double eccentric lug valves, or large-diameter flanged butterfly valves, TWT Valve delivers precision-machined solutions tailored to international standards (EN 1092-2, ANSI B16.1, AWWA C504, BS 5155).
Through our specialized OEM custom industrial valve solutions, we offer custom face-to-face dimensions, specialized seat materials (EPDM, NBR, Viton, Metal), and custom body coatings for aggressive media.
Learn more about our manufacturing heritage, advanced testing equipment, and global certifications on our About TWT Valve page.
Need Technical Drawings or Factory-Direct Pricing?
Not sure which connection style fits your engineering blueprints? Contact TWT Valve today to speak with our sales engineers, request 3D CAD models, or receive a competitive factory-direct proposal.