Product Range
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Metal Seated Triple Eccentric Butterfly Valve
Quick Specs 2" - 48" (DN50 - DN1200) Class 150 - 600 (PN 10 - 100) API 609, ASME B16.34, ISO 15848 (low-leakage) A216 WCB, A351 CF8M, A351 CF8, A182 F316 (forged for smaller sizes) Metal-to-metal (Stellite 6 overlay on seat ring, hardened disc edge), fire-safe per API 607 Triple eccentric (shaft offset from centerline in three planes—axial, radial, angular), cam-action disc rotation eliminates seat friction during 90° travel, zero rubbing contact until final 2-3° of closing, metal seat rated for cyclic high-temperature service Why Triple Eccentric Changes Everything Most butterfly valves rub. The disc scrapes across the seat every time it opens and closes. Elastomer seats can tolerate that rubbing—they're soft, they deform, they recover. Metal seats don't. If you rub Stellite against Stellite every cycle, you grind the seal surface down until it leaks. Triple eccentric geometry solves this at the structural level. The shaft is offset from the disc centerline in three planes—axial, radial, and angular. Those three offsets make the disc travel in a cam path. When you start opening the valve, the disc lifts off the seat immediately. It rotates freely through nearly the entire 90° stroke with zero contact against the seat ring. Only in the last 2-3 degrees of closing does the disc cam back into the seat and press into it for a seal. That means the Stellite overlay doesn't get ground away cycle after cycle. Metal-to-metal seating holds up for thousands of cycles in high-temperature service where elastomer would have burned out after the first week. Continuous service at 350°C and above? Short-term exposure pushing past 500°C? This is where triple eccentric metal-seated valves earn their place. When Fire Safety Isn't Optional A fire on a petrochemical line isn't a hypothetical. It's a scenario you design for. Elastomer seats burn. They soften. They lose seal integrity while the line is still pressurized. A metal seat doesn't burn. It doesn't soften. It maintains mechanical seal contact through a fire event because the seating surfaces are hardened alloy, not rubber. API 607 fire testing validates that. The valve gets burned, cooled, burned again—and it still holds its seal classification. Triple eccentric geometry helps here too, because the cam-action closing motion delivers consistent, repeatable seat contact force regardless of thermal expansion or distortion in the body. ISO 15848 fugitive emission compliance rounds out the qualification package for refining and petrochemical applications. Regulators and plant operators both want the same thing—valves that don't leak process fluid to atmosphere, and don't leak more under fire conditions. This valve delivers on both counts. What the Three Offsets Actually Do Let's break it down plain. The axial offset moves the shaft behind the disc plane so the disc swings away from the seat on the downstream side during opening. The radial offset places the shaft off the pipe centerline so the disc cam-lifts uniformly. The angular offset tilts the shaft axis relative to the seat plane so the disc makes a progressively tighter seal in those final degrees of closing—more contact force, better seal integrity, no over-compression that could damage the seat. All three work together. You can't get the same result with two offsets. Double eccentric reduces rubbing but doesn't eliminate it. Triple eccentric eliminates rubbing through the full stroke except for the sealing contact zone at closed position. That's the difference between a metal seat that lasts a season and a metal seat that lasts for years. FAQ A: Yes. Metal-to-metal seating rated for continuous 350°C+ service covers saturated and superheated steam lines in Class 150-600 range. Select body material per steam chemistry—WCB for standard conditions, CF8M for corrosive steam condensate. A: Gate valves work, but they're heavy, slow to stroke, and the wedging mechanism is prone to sticking after long periods in one position. Triple eccentric butterfly valves stroke in 90°, weigh less, and the cam-action geometry prevents seat binding. For frequent cycling in high-temperature service, butterfly is the better choice. A: ISO 15848 defines fugitive emission testing and classification. Low-leakage means the valve meets stringent emission rate limits under defined test conditions—temperature cycles, mechanical cycles, and sustained pressure. For petrochemical plants subject to environmental emission regulations, this qualification is a compliance requirement, not a marketing label. A: No. Stellite 6 overlay against hardened disc edge is a dry-metal seal pair. The cam-action geometry ensures the contact zone is limited to the final degrees of closing—no sustained sliding friction that would require lubrication. Seat integrity comes from geometry and material hardness, not from grease. A: Manual lever (sizes 2"-6"), manual gear operator (8"-48"), electric actuator, pneumatic cylinder. The 90° quarter-turn stroke is compatible with all standard rotary actuators. Positioner and limit switch integration per project requirements.
Pneumatic Centerline Butterfly Valve
Quick Specs 2" - 24" (DN50 - DN600) Class 150 / PN 10-16 Cast iron (GG25), ductile iron (GGG40), A216 WCB, A351 CF8M Resilient elastomer liner (EPDM, NBR, Viton, PTFE-coated) bonded to body bore—disc seals against the liner in both directions Concentric (centerline) shaft alignment—shaft center, disc center, and body center all on the same axis. Pneumatic cylinder actuator (single-acting spring-return or double-acting), positioner optional for modulating control API 609, MSS SP-67, EN 593 The Valve That Runs Your Plant's Basics Water lines. HVAC chilled water loops. General process isolation where the media isn't hot, isn't abrasive, isn't corrosive enough to justify a high-performance valve. That's the territory where centerline butterfly valves live—and they live there because the geometry is simple and the economics are straightforward. Concentric design means the shaft, the disc, and the body all share the same center axis. The disc rotates around its own center. When it closes, it presses into the elastomer liner bonded inside the body bore. The liner wraps around the disc edge 360°. That's bidirectional sealing built into the seat design—no preference for flow direction, no need to orient the valve based on pressure side. You don't need triple offsets here. You don't need metal seating. The elastomer liner does the sealing work, and elastomer is forgiving—it deforms under disc contact, recovers when the disc opens, and keeps sealing after thousands of cycles in normal water and light-process service. EPDM for water and steam condensate. NBR for oil and fuel. Viton when you need chemical resistance. PTFE-coated liner when the process demands a harder surface with some elastomer compliance underneath. Why Pneumatic Actuation Matters Manual butterfly valves are fine for lines that get opened and closed a few times a shift. But process plants don't run on manual labor anymore. Sequence control. Remote operation. Automated isolation on interlock signals. These are the reasons you put a pneumatic cylinder on a centerline butterfly valve. Single-acting spring-return actuators give you fail-safe positioning—spring closes the valve on air loss, which is the default for isolation duty. Double-acting actuators give you faster stroke speed and full control in both directions, which suits modulating service where the valve positions between open and closed. Add a positioner and you get proportional control—4-20mA signal drives the actuator to any angle between 0° and 90°. That turns a isolation valve into a control valve for flow regulation on water and HVAC lines. The pneumatic package mounts directly to the valve body through a bracket and coupling. No linkage geometry, no external drive train. Compact, clean, and the actuator torque goes straight into the disc shaft. Where Centerline Hits Its Limits Let's be honest about what this valve doesn't do. The elastomer liner has a temperature ceiling—EPDM handles around 120°C continuous, NBR and Viton push higher but not past 200°C sustained. Abrasive media wears the liner. High-pressure differential across a closed centerline valve can deform the disc and leak past the liner. That's why pressure ratings stop at Class 150 / PN 10-16. If your application exceeds those limits, you need a high-performance or triple eccentric valve. But for the majority of water distribution, HVAC, and general process isolation—where temperature is moderate, pressure is low, and media is compatible with elastomer—the pneumatic centerline butterfly valve is the most cost-effective automated quarter-turn valve available. No other automated valve type gives you bidirectional isolation at this price point with this installation simplicity. FAQ A: Yes, with a positioner. The pneumatic actuator responds to a 4-20mA input signal and positions the disc at any angle between 0° and 90°. Centerline butterfly valves are suitable for modulating control on water and HVAC lines where precision doesn't need to match a dedicated control valve. If you need tight flow regulation, consider a globe valve instead. A: Spring-return (single-acting) for isolation duty—valve fails closed on air loss, which is the safe default for process isolation. Double-acting for modulating service or applications where you need fail-open positioning. Spring-return costs less because you only need air supply on one side of the cylinder. A: EPDM for water, steam condensate, and mild chemical service—compatible with most HVAC and municipal water applications. NBR for petroleum-based fluids, oils, and fuels. Viton for aggressive chemicals, higher temperature, and broader solvent resistance. PTFE-coated liner when you need a hard seating surface with elastomer backup compliance. Match the liner to your media, not to your budget. A: Yes. The elastomer liner wraps the disc edge 360° and compresses equally regardless of which side the pressure comes from. No direction-dependent sealing, no need to orient the valve based on flow. Install it either way—sealing performance is identical. A: Minimal. Clean, dry instrument air is the main requirement—moisture and particulate contamination degrade cylinder seals over time. Annual inspection of the positioner and supply air filter. The elastomer liner in the valve body has a finite service life—plan for liner replacement per your cycle count and media conditions, typically every 5-8 years in standard water service.
Lug Centerline Butterfly Valve
Quick Specs 2" - 24" (DN50 - DN600) Class 150 / PN 10-16 Cast iron (GG25), ductile iron (GGG40), A216 WCB, A351 CF8M Resilient elastomer liner (EPDM, NBR, Viton) bonded to body bore Lug body—threaded lug holes in the body flange ears, bolts thread into the lugs from each side independently. Allows dead-end service (one flange disconnected, valve holds on the other side). Concentric shaft alignment, manual lever or gear operator. API 609, MSS SP-67, EN 593 The Lug Body Difference You Can See Look at the flange ears on a wafer butterfly valve. Through-holes. Bolts pass through the valve body and thread into nuts on the other pipeline flange. Both flanges clamp the valve in position together. Disconnect one flange and the valve is loose—it can slide, it can fall, it can't hold pressure from the remaining side. Now look at a lug body. Threaded holes in each flange ear. The bolt from the left pipeline flange threads into the lug on that side. The bolt from the right pipeline flange threads into the lug on the other side. Each flange bolts to the valve independently. Disconnect one pipeline flange, the valve stays bolted to the other side. It holds position. It holds pressure. It isolates the downstream line. That mechanical independence is the whole reason lug butterfly valves exist. Wafer valves are cheaper and lighter, but they require both flanges to be present and bolted. Lug valves cost a little more and weigh a little more, but they give you one-side isolation capability that wafer bodies simply cannot provide. Dead-End Service and Line Blanking Here's a scenario that plays out on every water distribution network and HVAC system. You need to isolate a downstream branch for maintenance. You close the valve. You disconnect the downstream flange to remove the branch piping. The valve is still bolted to the upstream flange. Upstream pressure is held by the closed valve. The upstream line stays in service while you work on the downstream side. A wafer valve can't do that. Remove one flange and the wafer body has nothing to clamp against—it shifts, it leaks, it becomes a hazard. The lug body threads each flange independently, so the valve remains mechanically anchored and sealed on whichever side is still connected. Dead-end service means the valve can be installed at the end of a line with only one pipeline flange. Line-blanking means you can use the valve as a blanking point—close it, disconnect downstream, and the closed valve becomes the line termination. These capabilities matter on every installation where you can't afford to shut down the upstream side to service the downstream side. Same Seating, Different Body Inside the lug body, the sealing mechanism is identical to the wafer centerline butterfly valve. Concentric geometry—shaft, disc, and body on the same center axis. Elastomer liner bonded to the body bore, disc compresses into the liner at closed position, bidirectional sealing from the 360° liner wrap. EPDM, NBR, Viton liner options matched to your media. The difference is purely in the body flange configuration. Same disc. Same seat. Same rotation. Same pressure and temperature limits. But the lug body gives you installation flexibility that the wafer body doesn't—one-side isolation, dead-end service, line termination, downstream maintenance without upstream shutdown. That's why HVAC engineers, water distribution designers, and any installer who values one-side mechanical independence specifies lug centerline butterfly valves. FAQ A: Any application where you might need to disconnect one pipeline flange while keeping the other side in service—HVVAC branch isolation, water distribution network branch valves, line termination points, dead-end installations. If both flanges will always remain connected and you just need a low-cost isolation valve, wafer is sufficient. If one-side independence matters, specify lug. A: Yes, within the rated pressure class. The threaded lugs anchor the valve to the connected flange, and the elastomer liner seals bidirectionally against disc contact. Dead-end service at Class 150 / PN 10-16 is standard duty for lug centerline butterfly valves in water and HVAC applications. A: Slightly. The lug ears with threaded holes add material compared to wafer through-holes. The weight difference is minimal in sizes 2"-12" and becomes more noticeable in larger sizes where the lug ears carry more bolt load. For most HVAC and water installations, the weight increase doesn't affect support requirements. A: Absolutely. Pneumatic cylinder, electric actuator, or manual gear operator—all the same actuation options as wafer centerline valves. The lug body doesn't change the shaft interface or the quarter-turn stroke geometry. Add a positioner for modulating control, same as any automated butterfly valve. A: Gate valves can handle dead-end service, but they're heavier, slower, and more expensive than a lug butterfly valve at the same size and pressure class. For water and HVAC isolation at Class 150, a lug butterfly valve isolates faster (90° stroke vs. multi-turn), weighs less, and costs less. If you need higher pressure or temperature, or if tight shutoff classification is required beyond elastomer liner capability, then consider gate or ball alternatives.
Wafer Double Eccentric Butterfly Valve
Quick Specs 2" - 48" (DN50 - DN1200) Class 150 - 300 / PN 10-40 A216 WCB, A351 CF8M, A351 CF8, ductile iron (GGG40) Resilient elastomer (EPDM/NBR/Viton) on disc edge, or PTFE/modified PTFE for higher temperature; optional metal seat ring with Stellite overlay for high-temperature configurations Double eccentric (high-performance)—shaft offset from disc center in two planes (axial + radial). Disc lifts off seat during initial rotation, reducing seat friction and extending cycle life. Wafer body—sandwich between pipeline flanges. API 609, ASME B16.34, EN 593 The Gap That Needed Filling Centerline butterfly valves seal well at low pressure. They're cheap, they're simple, they work. But push the pressure toward Class 300 and the disc starts deforming under differential load. Push the temperature past what elastomer can tolerate and the liner degrades. Push the cycle count into the thousands and the rubbing friction between disc and seat starts wearing out the elastomer. Triple eccentric metal-seated valves handle all of that. They seal at Class 600, they handle 350°C+, they cycle metal-on-metal without degradation. They also cost considerably more, and for many applications between centerline limits and triple eccentric territory, they're overkill. That's the gap. Double eccentric—what API 609 calls "high-performance butterfly valve"—fills it. Two shaft offsets move the disc off the seat centerline. The disc cam-lifts during the first degrees of rotation instead of sliding across the seat surface. Reduced rubbing. Extended seat life. Typically 3-5 times more cycles before seat replacement compared to concentric designs. Pressure handling up to Class 300. Temperature capability up to approximately 250°C with PTFE or modified PTFE seats. Metal seat option with Stellite overlay for moderate high-temperature service. All in a wafer body that sandwiches between pipeline flanges—the most space-efficient installation format available. Two Offsets, Real Results The axial offset places the shaft behind the disc centerline plane so the disc swings away from the seat on the downstream side during opening rotation. The radial offset positions the shaft off the pipe centerline so the disc lifts uniformly as it begins to rotate. Together, these two offsets create a cam-action motion—the disc separates from the seat in the first degrees of opening instead of dragging across it. That reduced contact friction is the key benefit. On a concentric valve, the disc scrapes across the elastomer liner through the entire 90° stroke. Every cycle scrapes the seat. After enough cycles, the liner wears thin, loses compression against the disc edge, and starts leaking. On a double eccentric valve, the disc only contacts the seat in the closed position and during the final degrees of closing. The rest of the stroke is frictionless. Seat material survives longer. Cycle intervals between maintenance stretch out. Plant uptime improves. The elastomer seat sits on the disc edge instead of in the body bore—that's another difference from centerline construction. Disc-edge seating gives you a tighter, more defined seal contact zone. PTFE and modified PTFE seats on the disc edge push the temperature ceiling higher than body-bore elastomer liners. Metal seat rings with Stellite overlay on the disc take you into moderate high-temperature territory without jumping to triple eccentric pricing. Wafer Format Keeps It Lean Wafer body means the valve sandwiches between two pipeline flanges. Through-holes in the body flange ears. Bolts pass through the valve and thread into the pipeline flange nuts on both sides. No valve flanges of its own. The pipeline flanges carry the bolt load. The valve sits in the gap between them. That makes the wafer double eccentric butterfly valve the most compact high-performance quarter-turn valve you can install. Face-to-face dimensions follow API 609 short pattern or long pattern. The short pattern fits the same face-to-face space as a centerline wafer valve. The long pattern gives you a longer body bore for improved flow characteristics at higher pressure. Either way, the installation footprint is smaller than a flanged gate valve, smaller than a flanged ball valve, and the weight is lower too. Cost sits between centerline and triple eccentric. You pay more than a centerline valve for the double offset geometry and the higher pressure/temperature capability. You pay less than a triple eccentric valve because you don't need three offsets and metal seating isn't mandatory. For process lines running Class 150-300 at temperatures that exceed elastomer liner comfort but don't demand full metal-to-metal fire-safe seating, this is the right valve. FAQ A: API 609 categorizes butterfly valves as Category A (centerline/concentric) and Category B (offset/high-performance). Double eccentric valves fall into Category B because the shaft offsets move the disc off the seat centerline, creating cam-action rotation. Category B covers higher pressure classes, reduced seat friction, and extended cycle life compared to Category A. A: Modified PTFE seats on the disc edge handle temperatures up to approximately 250°C continuous, which covers many saturated steam applications in the Class 150-300 range. For superheated steam or temperatures above 250°C, specify the metal seat option with Stellite overlay, or move to a triple eccentric metal-seated valve. A: Wafer format keeps cost and weight down. If your application requires one-side isolation, dead-end service, or line-blanking capability, specify the lug body version. For standard inline isolation where both pipeline flanges remain connected, wafer is the standard and most cost-effective choice. Both body formats use the same double eccentric internals. A: Resilient elastomer seats on double eccentric valves typically deliver 3-5 times more cycles than equivalent seats on concentric valves, because the cam-action geometry reduces seat friction during rotation. Exact cycle life depends on media, temperature, pressure differential, and stroke frequency. In standard water and light-process service, expect 50,000+ cycles before seat intervention. In more demanding conditions, plan for earlier scheduled maintenance. A: When your application requires Class 300+ sustained pressure, metal-to-metal fire-safe seating per API 607, continuous service above 250°C, or ISO 15848 fugitive emission compliance for petrochemical service. Double eccentric handles the middle ground—Class 150-300, moderate temperature, resilient or PTFE seating. Triple eccentric handles the demanding end—Class 600, high temperature, metal seating, fire-safe qualification.
Multi-layer Seated Triple Eccentric Butterfly Valve
Quick Specs Size: 2" - 48" (DN50 - DN1200) Pressure: Class 150 - 600 (PN 10 - 100) Standard: API 609, ASME B16.34, API 607 (fire-safe), ISO 15848 Body Materials: A216 WCB, A351 CF8M, A351 CF8, A182 F316 Seat: Multi-layer composite seat—stainless steel or Stellite base ring + flexible graphite sealing layer + optional elastomer cushion layer Design: Triple eccentric geometry (three-plane shaft offset), cam-action disc rotation Why This Seat Exists Metal-seated triple eccentric valves handle high temperature beautifully. But at ambient? Microscopic gaps in metal-to-metal contact mean measurable leakage—not terrible, but not zero. Elastomer-seated valves seal bubble-tight at room temperature, every time. Until fire hits. Then the rubber burns away and nothing holds that line. The multi-layer seat solves both in one component. A stainless steel or Stellite base ring provides structural backbone. On top sits a flexible graphite sealing layer that compresses against the disc edge—bubble-tight at normal temperatures. When fire conditions char the graphite at 800°F+, the metal base ring underneath still holds the disc and maintains seal integrity. That's why petrochemical specs are shifting toward multi-layer seats. You don't choose between "tight at ambient" and "alive after a fire." This seat delivers both. Three Offsets Protect the Graphite Triple eccentric means three offset planes between the shaft centerline and the disc sealing surface. Combined, they produce cam-action rotation—the disc lifts off the seat immediately instead of scraping across it. Less scraping means less wear on the graphite layer. If you've ever replaced a soft seat that looked like it was dragged across sandpaper, you understand why cam-action matters for composite seats. The graphite is durable, but not indestructible. Triple eccentric geometry protects it across thousands of cycles. Where Engineers Specify This Refining crude units with temperature swings from 650°F process conditions to ambient during shutdowns. Chemical reactors running hot but isolated at room temperature for maintenance. Offshore platform fire-safe isolation valves that also must meet ISO 15848 emissions compliance. If your spec demands API 607 AND bubble-tight at ambient, this valve checks both boxes without a secondary isolation valve downstream. Installation Reality Never over-torque flange bolts. The graphite layer compresses under load, but excessive bolt tension crushes it beyond recovery. Follow cross-pattern incremental torque. On 24"+ sizes, check seat compression after initial bolt-up—if air leaks past at ambient pressure test, one more torque pass before the graphite fully seats against the disc edge. Once compressed correctly, it holds. FAQ A: Yes. The flexible graphite layer closes the microscopic gaps that pure metal-to-metal seats leave at ambient. Bubble-tight is achievable and repeatable. A: The graphite chars. The metal base ring maintains seal contact against the disc. The valve passes fire-safe testing because the metal ring provides the structural sealing surface after the graphite is consumed. A: Yes. Remove the disc, extract the old seat ring, install the new one, reassemble. On 24"+, plan for two technicians and a clean surface—no debris between the graphite and disc edge during reassembly. A: Pure metal seats pass fire-safe tests but often allow measurable leakage at ambient. If your spec requires both fire-safe and tight shutoff at normal conditions, pure metal may not satisfy the ambient leakage requirement.
Forged Metal Seated Butterfly Valve
Quick Specs Size: 2" - 12" (DN50 - DN300) Pressure: Class 150 - 900 (PN 10 - 150) Standard: ASME B16.34, API 609, ISO 15848, API 607 (fire-safe) Body Materials: A182 F316 (forged), A182 F51/F53 (forged Duplex/Super Duplex), A182 F5/F9/F11/F22 (forged Cr-Mo), A182 F304 (forged) Seat: Metal-to-metal (Stellite 6 or tungsten carbide overlay on seat ring and disc sealing edge) Design: Forged body construction, triple eccentric or double eccentric geometry Why Forged, Not Cast Cast bodies work fine at Class 150-300. Wall thickness is generous, porosity gets caught in radiography, pressure holds. Push past Class 600 into 900 territory on a 4" or 6" valve, and the math changes. Casting porosity—microscopic voids from solidification—becomes a failure initiation point under sustained high-pressure loading. The wall is thin relative to the pressure it carries. A void in a thin wall at 1500 PSI isn't cosmetic. It's a crack waiting to start. Forging eliminates that risk. A forged A182 F316 or F51 body has uniform grain structure through every section of the pressure boundary. No voids. No hidden porosity. Every square millimeter has the same tensile strength, same yield point, same ductility. ASME B16.34 allows forged bodies higher pressure ratings with confidence because material integrity is predictable. The tradeoff: forging costs scale with size. A forged 12" body is expensive but manufacturable. Above 12", forging becomes prohibitive and wall thickness increases enough to manage casting porosity through RT inspection. That's why this product stops at 12"—economics make casting rational above that size. Hard Seats That Don't Wear Out Stellite 6 overlay on the seat ring. Tungsten carbide on the disc sealing edge. Two hard surfaces cycling against each other every operation. Metal-to-metal seating sounds like it should wear fast—it doesn't, because eccentric geometry lifts the disc off the seat immediately during opening. No sliding contact. No gouging. After 10,000 cycles, the seat still holds. After 50,000, wear is still within tolerance. Slurry lines, catalyst recovery, abrasive streams that destroy elastomer seats in weeks—these surfaces take the punishment and keep sealing. Duplex for Corrosive Service A182 F51 and F53 forged bodies handle chloride environments that eat standard stainless. Offshore seawater injection. Desalination brine. Process streams where 316L pits within months. Duplex forged bodies give corrosion resistance plus pressure boundary integrity in one spec. No casting with supplemental NDE requirements—the forging is clean by definition. FAQ A: Radiography catches visible porosity, not microscopic voids. At Class 900 on a thin-wall small body, a void too small for RT can still initiate a fatigue crack under cyclic loading. Forging removes that uncertainty. A: A182 F22 forged bodies rate for sustained service up to approximately 1050°F per ASME B16.34. F5 and F9 cover lower ranges in the Cr-Mo family. A: The seat ring is replaceable. The disc overlay is not field-repairable—Stellite and tungsten carbide require controlled shop environments for reapplication. Plan spares for critical service. A: Forging above 12" becomes economically impractical. Press requirements, material volume, and machining costs exceed market acceptance. Larger sizes use casting with proper NDE—increased wall thickness accommodates porosity management.
Lug Multi-layer Seated Butterfly Valve
Quick Specs 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. Material Choices 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. FAQ 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.
Butt Welded Eccentric Butterfly Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 600 / PN 10-100 Standard: ASME B16.34, API 609, ISO 15848 Body Materials: A216 WCB, A182 F316 (forged for smaller sizes), A351 CF8M Seat: Metal-to-metal (Stellite 6 overlay) or multi-layer composite seat (metal base + flexible graphite) Design: Butt-weld end connections (beveled per ASME B16.25), double eccentric or triple eccentric geometry No Flanges, No Gaskets, No Leak Paths Every flanged connection has two failure points: the gasket and the bolts. Gaskets age and compress unevenly. Bolts relax under thermal cycling, lose preload, and the gasket drops below sealing compression—now you've got a leak path you can't see until it shows up as emissions or a drip on the floor. At Class 600+, flanged connections require heavy bolting and thick gaskets, and they're still the weakest seal in the line. Butt-weld ends eliminate both. Valve ends are beveled per ASME B16.25. Weld them directly to the pipe. No gasket between valve and pipeline. No bolt pattern to maintain. No external leak path. Once the weld is made, inspected, and accepted, that connection is permanent. It doesn't age. It doesn't relax. It doesn't leak. This matters in three scenarios. Class 600+ high-pressure lines where every flange is a maintenance item and emissions source. Buried or submerged installations where bolt retorquing requires excavation. Fire-safe systems where gaskets burn—welded joints don't. Welded In Means Permanent The tradeoff is straightforward. A butt-welded butterfly valve cannot be removed without cutting it out. When you weld this valve into the line, it becomes a permanent pipeline component. That's why some installations specify butt-welded ends. Underground vaults, submarine crossings, high-pressure fire-safe lines where you want minimum external leak points—permanent installation is the correct engineering choice. You plan for it to stay for the life of the pipeline. If your installation requires periodic valve removal, specify flanged ends. Butt-welded is for permanent service. Eccentric Geometry Protects Both Seat Types Cam-action disc rotation from double or triple eccentric geometry lifts the disc off the seat immediately instead of sliding. For the Stellite 6 metal-to-metal seat, that means no grinding across the hard facing every cycle—the overlay survives abrasive and high-temperature service. For the multi-layer composite seat, the graphite layer isn't scraped away during rotation—bubble-tight performance holds across thousands of cycles. Lower seat friction also reduces operating torque. Smaller actuators, easier manual operation. On a valve permanently installed in an underground vault, lower torque means no oversizing—less weight, less maintenance in inaccessible locations. FAQ A: Zero external leak path at the valve-to-pipeline connection. No gasket, no bolts, no mechanical seal that relaxes over time. The welded joint is permanent and code-compliant. A: Only by cutting the welds. This is a permanent installation valve. If the application requires periodic removal, specify flanged ends. A: Metal-to-metal Stellite 6 for high-temperature, abrasive, or cycling service above 500°F where fire-safe certification is required and ambient leakage tolerance is acceptable. Multi-layer composite when you need both fire-safe and bubble-tight at ambient in the same valve. A: Valve ends are beveled per ASME B16.25. Welding procedures, filler materials, and PWHT must comply with ASME B31.3 or applicable project code. WCB uses standard carbon steel procedures. F316 requires stainless filler and controlled heat input. A: Yes. Butt-welded ends are preferred for buried and submerged piping—no gaskets to leak, no bolts to corrode. Specify external coatings per project requirements for the body material in that environment.
Technical Overview
Butterfly valves rotate a disc 90° inside the flow path to open or close—the simplest quarter-turn mechanism in industrial valve design. That simplicity is the reason butterfly valves dominate water, HVAC, and general process isolation: one moving part, one 90° stroke, one sealing interface, minimal space envelope, lowest cost per diameter inch of any shutoff valve type. FLOWKS manufactures eight butterfly valve configurations spanning three sealing philosophies and three body connection formats. Concentric (centerline) designs align the shaft, disc, and body on the same axis—the disc slides across the seat surface during rotation, simple and cheap but limited in pressure rating and cycle life. Double eccentric (high-performance) designs offset the shaft in two planes so the disc cam-lifts off the seat during opening, reducing rubbing and extending elastomer seat life by 3-5x. Triple eccentric designs offset the shaft in three planes so the disc only contacts the seat at the final 2-3° of closing—frictionless travel that enables metal-to-metal seating for high-temperature and fire-safe service. Seat types range from resilient elastomer liners (EPDM, NBR, Viton—bubble-tight, low-cost, temperature-limited) through metal seats (Stellite 6 overlay—fire-safe, high-temperature, slight ambient leakage) to multi-layer composite seats (metal base ring + flexible graphite layer—bubble-tight at ambient AND fire-safe under fire conditions). Body connections include wafer (sandwich between flanges, slimmest, cheapest), lug (threaded ears, one-side isolation capability), and butt-weld (permanent welded-in installation, zero external leak paths). Pneumatic, electric, hydraulic, and manual actuation options cover the full range of process automation requirements.
FLOWKS butterfly valves provide quarter-turn shutoff across the widest range of process conditions—from HVAC water isolation at Class 150 to petrochemical high-pressure high-temperature service at Class 900. Concentric centerline butterfly valves with resilient elastomer liners deliver cost-effective bidirectional sealing for water, wastewater, and light-process applications. Double eccentric high-performance butterfly valves reduce seat friction through cam-action disc rotation, extending elastomer cycle life and enabling Class 150-300 service with tighter shutoff. Triple eccentric butterfly valves with metal-to-metal Stellite seats eliminate elastomer entirely—rated for 350°C+ continuous temperature, fire-safe per API 607, ISO 15848 low-leakage fugitive emission compliant. Multi-layer composite seats combine bubble-tight ambient sealing with fire-safe metal backup for petrochemical installations that demand both capabilities. Wafer bodies offer the slimmest installation footprint between pipeline flanges. Lug bodies enable dead-end service and one-side isolation through independent threaded flange ears. Butt-welded ends eliminate flange gaskets entirely for permanent high-pressure and buried installations. Forged body construction provides casting-free pressure boundary integrity for severe service at small sizes. Pneumatic, electric, hydraulic, and manual gear actuation available across all configurations.
Product Downloads
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Engineering Calculators
Free online tools to help you select and size Butterfly Valves.
Industries Using Butterfly Valves
See how Butterfly Valves are applied across different industrial sectors.
Petrochemical
Corrosion-resistant valves for aggressive media in chemical processing plants. FLOWKS alloy and fluorine-lined valves are engineered to handle the most challenging petrochemical environments.
Water Treatment
Reliable flow control solutions for desalination, wastewater, and potable water systems. FLOWKS butterfly valves and check valves are widely used in water infrastructure projects.
LNG
Cryogenic valves engineered for liquefied natural gas processing and transportation. FLOWKS cryogenic service valves are tested to -196°C per BS 6364.
Mining
Abrasion-resistant valves for slurry, tailings, and mineral processing applications. FLOWKS knife gate valves and butterfly valves are built to withstand harsh mining environments.
Looking for More Solutions?
Discover our range of products built for your industry's challenges.
Ball Valves
FLOWKS offers floating ball valve, trunnion mounted ball valve and top entry ball valve for oil & gas, petrochemical and power generation. Designed per API 6D, API 608 and ASME B16.34.
DBB Valves
FLOWKS Double Block & Bleed (DBB) valves provide dual isolation with bleed verification in a single compact body. Replacing traditional multi-valve installations, FLOWKS DBB valves reduce weight, space and potential leak paths. Available in bolted bonnet, all-welded and expanding gate designs per API 6D and API 607.
Gate Valves
FLOWKS gate valves for isolation service in piping systems. Flexible wedge, solid wedge, slab and expanding gate designs per API 600, API 602 and ASME B16.34.
Globe Valves
FLOWKS globe valves for throttling and isolation. Standard, angle, Y-pattern and bellows seal configurations per API 602 and BS 1868.