Lug Multi-layer Seated Butterfly Valve

Size: 2" - 24" (DN50 - DN600)

Pressure: Class 150 - 300 / PN 10-40

Standard: API 609, API 607 (fire-safe), EN 593

Body Materials: A216 WCB, ductile iron (GGG40), A351 CF8M

Seat: Multi-layer composite seat—metal base ring + flexible graphite sealing layer

Design: Lug body with threaded flange ears, double eccentric or triple eccentric geometry

The Lug Body Holds Itself In the Line

Lug butterfly valves stay in the pipeline when you unbolt one side. Threaded ears on the body—one set per flange side—accept bolts independently. Unbolt downstream, remove the pipe section, and the valve stays. Upstream bolts hold it. That's dead-end service. That's downstream isolation without pulling the valve.

Wafer bodies don't do this. Unbolt one side and the wafer valve drops out. If you need one-side isolation—servicing downstream equipment while upstream stays pressurized—you need a lug body. Refinery isolation points, petrochemical line terminals, offshore manifold stations require exactly this. The maintenance team unbolts one side, works, and bolts back up. The valve never leaves the line.

Multi-layer Seat: Tight at Ambient, Alive After Fire

The composite seat stacks a metal base ring underneath a flexible graphite sealing layer. Normal operation: graphite compresses against the disc edge for bubble-tight shutoff. Zero visible leakage. ISO 15848 compliant. Fire conditions: graphite chars, metal base ring maintains seal contact. API 607 fire-safe passed.

Petrochemical specs increasingly demand multi-layer seats on isolation valves because you can't afford a valve that seals perfectly at normal temperature but fails under fire. You also can't afford one that survives fire but leaks enough at ambient to violate emissions compliance. Multi-layer covers both in one component. No secondary isolation valve needed downstream.

Where This Combination Matters

Refinery isolation points with downstream maintenance access and hydrocarbon fire-safe requirements. Petrochemical line terminals between process units—fire-safe and tight shutoff both mandatory. Offshore platform installations where lug bodies allow module-by-module isolation during maintenance campaigns without removing valves. Any installation needing dead-end service AND fire-safe certification AND bubble-tight ambient leakage—this valve checks all three.

A216 WCB carbon steel for standard refinery service—cost-effective, handles Class 150-300. Ductile iron GGG40 for water and wastewater where carbon steel is unnecessary. A351 CF8M stainless for corrosive streams and chloride environments. The multi-layer seat configuration stays consistent across all three body options.

A: Wafer has no threaded ears—bolts pass through between flanges. Unbolt one side and the valve falls out. Lug has threaded ears per flange side, allowing independent bolting and one-side isolation.

A: Yes. The graphite chars under fire exposure, but the metal base ring maintains seal integrity against the disc. Both through-seat and external leakage requirements are met.

A: Yes, within Class 150-300. The independent bolting per side allows one flange removal while upstream holds the valve under full line pressure. Confirm the specific dead-end rating for your size and material.

A: The seat ring is replaceable. Flexible graphite provides long service life under normal conditions. If leakage develops after extended cycling, replace the seat ring—no need to replace the valve. Avoid over-torquing flange bolts during installation, which crushes the graphite beyond recovery.

A: GGG40 is adequate for water, wastewater, and low-corrosion utility applications. Less expensive than WCB, sufficient mechanical properties for Class 150-300. For hydrocarbon or corrosive service, specify WCB or CF8M.