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| The SDF Heavy Duty Lug Butterfly Valve represents a premium milestone in fluid isolation technology, explicitly designed to serve as a high-integrity, space-saving solution within demanding industrial process networks. In large-scale piping systems—such as those found in water treatment facilities, chemical processing plants, power station cooling loops, and marine utility lines—the management of fluid flow requires a balance between robust mechanical reliability and structural space efficiency. While traditional gate or globe valves provide dependable isolation, their massive face-to-face dimensions and extensive weights place significant structural strain on pipe hangers and complicate tight space installations. The SDF Lug Butterfly Valve solves this challenge by delivering an exceptionally compact, lightweight profile without sacrificing sealing tightness or pressure containment capabilities.The SDF Heavy Duty Lug Butterfly Valve represents a premium milestone in fluid isolation technology, explicitly designed to serve as a high-integrity, space-saving solution within demanding industrial process networks. In large-scale piping systems—such as those found in water treatment facilities, chemical processing plants, power station cooling loops, and marine utility lines—the management of fluid flow requires a balance between robust mechanical reliability and structural space efficiency. While traditional gate or globe valves provide dependable isolation, their massive face-to-face dimensions and extensive weights place significant structural strain on pipe hangers and complicate tight space installations. The SDF Lug Butterfly Valve solves this challenge by delivering an exceptionally compact, lightweight profile without sacrificing sealing tightness or pressure containment capabilities. Our Wafer Butterfly Valves deliver a high-efficiency, lightweight, and economical choice for bidirectional flow control in large-diameter piping systems. Designed to be sandwiched between standard pipe flanges, this valve utilizes a streamlined concentric disc and a replaceable elastomeric liner (EPDM/NBR/Viton). The engineered disc geometry maximizes flow area while lowering operating torque, providing smooth throttling, reliable bubble-tight shut-off, and low wear across long-term operations. | |||||||||
The defining feature of the Lug-style configuration is its set of threaded metal lugs spaced precisely around the perimeter of the valve body. These built-in lugs are machined to align with the bolt circle of standard pipe flanges. Unlike wafer-style butterfly valves, which are held in place by long bolts passing all the way through, the lug design uses separate bolts screwed directly into the valve body from both sides.
This structural setup enables a critical safety feature: Dead-End Service Capability. If downstream piping needs repair, maintenance, or replacement, technicians can completely unbolt and remove the downstream pipe section. The Lug Valve stays securely attached to the upstream flange, serving as a reliable pressure barrier holding back full upstream pressure. This eliminates the need for expensive facility-wide shutdowns, allowing maintenance teams to work safely on isolated sections.
The internal mechanics of the SDF series are built to reduce fluid turbulence and maximize the flow coefficient (Cv). The valve uses a streamlined concentric disc design that splits incoming flow smoothly, minimizing local vortex formation and pressure drop. The valve body is cast from heavy-walled, high-tensile Ductile Iron or Cast Carbon Steel (WCB), providing strong resistance against pipeline bending stress and external impact.
Reliable sealing depends on a replaceable elastomeric seat liner (such as EPDM, NBR, or Viton) that completely lines the valve bore. When closed, the precision-machined disc edge presses firmly into the flexible rubber seat to form a bubble-tight seal. The seat liner features integrated O-ring profiles along its flange faces, eliminating the need for separate gaskets during installation and keeping fluids from contacting the metal body.
Safe Dead-End Capability: Threaded lugs allow downstream piping to be removed while the valve remains fully pressurized on the upstream side.
Precise Bolt Alignment and Vibration Resistance: Threaded lugs center the valve perfectly between flanges during installation, preventing disc jamming and stopping shifting caused by high vibration.
Replaceable Heavy-Duty Seat Liner: The full rubber liner isolates the body from fluid, preventing internal corrosion and providing bubble-tight shutoff.
Direct ISO 5211 Mounting Pad: The top flange features an integrated ISO 5211 mounting pad, allowing pneumatic rack-and-pinion actuators to mount directly without adaptation brackets.
Technical Parameter | Standard Specification | Options and Upgrades |
Nominal Size Range | DN50 to DN600 (2 inch to 24 inch) | Larger sizes up to DN1200 on request |
Body Metallurgy | Ductile Iron (GGG40/50) / Cast Steel (WCB) | Stainless Steel (CF8M) for corrosive media |
Disc Material Options | Stainless Steel 316 (SS316) / Nylon-Coated DI | Al-Bronze (C95800) for seawater applications |
Elastomeric Liner Compound | EPDM (Standard) / NBR (Nitrile) | Viton (FKM) / PTFE for chemicals and oils |
Nominal Pressure Rating | PN10 / PN16 / Class 150 | High-pressure configurations available |
Flange Compatibility | ASME B16.5 Class 150 / EN 1092 PN10/PN16 | Threaded lug holes tailored to standard spec |
Top Mounting Interface | ISO 5211 Direct Pad | Accommodates levers, gears, or actuators |
Sealing Leakage Class | ANSI/FCI 70-2 Class VI / ISO 5208 Rate A | Zero-leakage bubble-tight validation |
The heavy-duty design of this lug butterfly valve makes it ideal for handling high-volume, low-to-medium pressure liquid systems:
Municipal Water and Wastewater: Raw intake water filtration, sludge processing, and main discharge pumps.
HVAC Chilled and Hot Water: Centralized high-rise HVAC networks, cooling tower supply headers, and condenser water lines.
Industrial Cooling Systems: Cooling water lines in steel mills, manufacturing plants, and automotive assembly facilities.
Marine Utilities and Desalination: Shipboard ballast transfer headers, seawater cooling systems, and reverse-osmosis pre-filtration skids.
To maximize seat liner life and ensure safe dead-end operation, follow these installation guidelines:
While the valve handles full working pressure (such as PN16) when clamped between two flanges, mechanical loads shift during dead-end service because the downstream flange support is gone.
Engineering Rule: When using a lug valve for continuous dead-end service at the end of a header, always reduce the maximum allowable operating pressure by 30% to 50% (unless a factory retaining ring is installed) to prevent pressure from distorting the rubber seat.
EPDM Liners: Best for general water utilities, chilled water, and mild acids. Never use EPDM in lines with compressed air oils, hydrocarbons, or petroleum products, as oil causes EPDM to swell, blister, and jam the disc.
NBR (Nitrile) Liners: Recommended for oil-lubricated compressed air lines, hydraulic returns, and fuel oil transfer streams under 80 degrees Celsius.
Viton (FKM) Liners: Recommended for high-temperature applications or chemical lines containing aggressive solvents.
Because lug valves have internal threads, bolt lengths must be calculated precisely. If a bolt is too long, it will bottom out inside the lug hole before fully tightening the flange, causing joint leaks. Always calculate bolt length based on flange thickness, washer thickness, and the thread depth of the lug.
When pairing the valve with automated actuators, always add a 20% to 30% safety factor above the baseline wet breakaway torque. If the valve stays closed for long periods, the rubber seat conforms around the disc edge, causing a higher initial opening torque. The actuator must have enough power to overcome this resistance cleanly.
Maximum Space and Weight Savings: Much lighter than gate or ball valves of equal size, reducing the need for heavy pipe supports.
Bidirectional Bubble-Tight Seal: The resilient seat profile guarantees leak-free shut-off in both flow directions.
Low Operating Torque: The streamlined disc reduces the force needed to open and close, allowing for smaller actuators.
Versatile Body Design: Built with universal positioning holes compatible with ANSI, DIN, JIS, and BS flange standards.
1. When can I get a quotation?
We typically provide a quotation within 4 hours of receiving your inquiry. Urgent requests are given priority.
2. Do you support customized valves?
Yes. We support OEM and customized valve orders based on drawings, specifications, and special working conditions.
3. What is the production lead time?
Normally, production takes up to 15 working days after order confirmation, depending on product type and quantity.
4. What standards do your valves comply with?
Our products comply with GB, ANSI, API, JIS, DIN, BS, and other international standards.
5. What pressure, size, and temperature ranges can you supply?
Pressure Range: Class 150 to Class 3500
Size Range: DN10 to DN3000
Temperature Range: -196 degrees Celsius to 610 degrees Celsius
6. What certifications do you have?
We are ISO 9001 and CE certified, and we provide third-party inspection and test reports upon request.
7. What delivery and payment terms do you offer?
Delivery terms: EXW, FOB, CFR, CIF
Payment terms: T/T (30% deposit + 70% balance), L/C, and other agreed terms.
8. Do you provide technical support and spare parts?
Yes. We offer 24/7 technical support and supply spare parts for long-term service.
