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Swing Check Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 600 / PN 10-100 Standard: API 6D, ASME B16.34, MSS SP-71 Body Materials: A216 WCB, A351 CF8M, A351 CF8, cast iron (GG25), ductile iron (GGG40) Seat: Metal-to-metal — disc face contacts body seat ring for shutoff. Stellite overlay on disc and seat ring available for abrasive/erosive service. Disc: Swing disc on hinge pin — disc swings open with forward flow (up to 80° maximum opening angle), swings closed when forward flow stops. Hinge pin mounted inside the body bore on the inlet side. Disc weight and flow velocity determine opening dynamics. Design: Flanged or butt weld ends. Full-bore body passage — disc opening angle doesn't restrict flow when fully open. Bolted body cover for hinge pin access. Disc swings freely—no spring assist, gravity closure. Why the Swing Check Is the Default Choice Walk into any pump house and you'll find swing check valves on the discharge lines. Not because they're fancy—they're not. They're the default because the mechanism is dead simple. A disc hangs on a hinge pin inside the body. Forward flow pushes it open. Flow stops, the disc swings back shut by gravity. No springs. No close-tolerance machining. No parts that wear out from friction against each other every cycle. That simplicity translates directly to reliability. Fewer moving parts, fewer failure modes, longer service intervals. For a pump discharge line where the pump runs steady and the check valve sits open most of the day, you don't need anything more complicated. Low Pressure Drop — Full Bore at 80° Open Here's the number that matters: 80° maximum disc opening angle. At full forward flow, the disc swings to 80° and the flow path through the valve body is nearly full bore. The disc isn't sitting in the stream throttling the flow like it does in a lift check or a dual plate design where the hinge pin and spring occupy the bore. That low pressure drop is why swing checks dominate on pump discharge lines. You sized that pump to deliver a certain flow at a certain head. The last thing you want is a check valve eating 2-3 psi of your pump output just sitting there doing its job. With a swing check at 80° open, the pressure loss through the valve is minimal—close to an open pipe segment of the same diameter. Metal-to-Metal Seating — and When You Need Stellite Standard seating is disc face against body seat ring, metal on metal. That's the default because it works across the widest range of process conditions—steam, water, oil, gas, moderate temperatures, frequent cycling. The disc contacts the seat ring with enough force to seal under normal backpressure. But if your process media carries abrasive particles—sand in water service, catalyst fines in refining, slag in steel mill cooling water—plain metal-on-metal seating wears fast. The disc face and seat ring erode from particle impact every time the valve cycles. Stellite overlay on both the disc face and the seat ring is the upgrade for abrasive and erosive service. Stellite is a cobalt-chromium alloy that resists erosion and abrasion far better than base carbon steel or stainless. It costs more, but it keeps the seat sealing surface intact for years instead of months in abrasive media. The Slam — What Happens When the Pump Trips This is the swing check's real limitation. When forward flow stops abruptly—pump trip, emergency shutdown, power failure—the disc swings back fast and hits the seat with impact. No spring to slow it. No dashpot to damp it. Just gravity and reverse-flow pressure accelerating the disc into the seat. That slamming action causes three problems. Water hammer—the pressure spike from the sudden disc closure travels back up the pipeline and can damage pipe supports, burst fittings, or overload downstream equipment. Seat damage—repeated slamming deforms the seat sealing surface over time, and the valve starts leaking in the closed direction. Disc wear—the disc hinge pin and disc body accumulate fatigue from repeated impact cycles. If your system has frequent pump start/stop sequences, or if the pipeline is long and water hammer risk is real, the standard swing check is not the right choice. An external pin swing check with a dashpot slows the closure. A dual plate check closes faster with shorter disc travel and less slamming energy. But for steady-flow pump discharge protection where the pump runs continuously and the check valve rarely cycles, the swing check is the simplest, most reliable, and most cost-effective option. FAQ Up to 80° at full forward flow. That gives near-full-bore passage through the valve body with minimal pressure drop. No. The disc closes by gravity and by reverse-flow backpressure if present. No spring assist. This is the simplest closing mechanism—no spring to fatigue, no spring to replace during maintenance. When the process media contains abrasive or erosive particles—sand, catalyst fines, slag, or similar solids in the flow stream. Also recommended for applications with frequent cycling (pump start/stop sequences) where repeated disc impact accelerates seat wear. Not recommended for standard gravity-closure swing checks. In vertical upward flow, gravity works against disc closure—the disc hangs open and only closes when reverse flow pushes it down. For vertical installations, use a spring-assisted check valve (dual plate or lift check) instead. Abrupt disc closure when forward flow stops suddenly—typically on pump trip or emergency shutdown. The disc swings back fast and impacts the seat, generating a pressure spike that travels upstream. If water hammer is a concern, consider an external pin swing check with dashpot or a dual plate check valve.
Butt Weld Swing Check Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 2500 / PN 10-420 Standard: API 6D, ASME B16.34, MSS SP-71 Body Materials: A182 F316 (forged), A182 F304 (forged), A182 F22/F91 (forged Cr-Mo for high-temperature). Forged body eliminates casting defects at high-pressure ratings. Seat: Metal-to-metal with Stellite overlay standard—high-pressure applications demand harder seat surfaces that survive disc impact slamming force at Class 600+. Disc: Swing disc on hinge pin, same mechanism as flanged swing check. Opening angle up to 80°. Gravity closure. Design: Butt weld ends—valve welds directly into the pipeline. No flanged connections, no flange gasket leak paths. Forged body for high-pressure integrity. Bolted or welded body cover options (welded cover eliminates one more potential leak path for extreme pressure/temperature service). Why Butt Weld Instead of Flanged Two reasons. Both of them come down to the same thing: you don't want leak paths on a passive component that operates automatically with no manual intervention. Reason one—high pressure. At Class 600 and above, flanged connections get expensive. The flanges are heavier, the bolting is larger, and the gaskets become a reliability liability. High-pressure gaskets cold-flow under sustained load. They creep. They leak. A flanged swing check at Class 900 with a leaking gasket means you have to shut down the line to re-torque or replace the gasket, because you can't tighten a flange on a running check valve—you can't access it safely under pressure. Butt welding eliminates the gasket entirely. The valve welds directly into the pipe. Permanent joint, zero gasket leak path. Reason two—hazardous and high-temperature service. Hydrogen service, steam at 600°F and above, high-pressure gas lines. Every flanged joint is a potential emission point. The gasket, the bolt stress relaxation over thermal cycles, the flange face condition after years of service. On a check valve—a component that sits there passively, cycling automatically on flow direction—you have no opportunity to monitor or tighten a flanged connection during operation. Butt weld it in and the joint is permanent. No gasket to degrade. No bolts to relax. No flange faces to inspect. Forged Body — No Casting Defects at High Pressure Cast bodies work fine at Class 150 and 300. The casting process produces parts with adequate wall thickness and acceptable porosity levels for those pressure ranges. At Class 600 and above—Class 900, 1500, 2500—casting defects become unacceptable. Porosity in a cast body under sustained high pressure can leak through the body wall. Surface shrinkage cavities can initiate cracks under cyclic pressure loading. Forged bodies eliminate those defects. The forging process compacts the metal grain structure, closes internal voids, and produces a body with uniform mechanical properties through the full wall thickness. No porosity. No shrinkage cavities. No internal defects that become leak paths under sustained high-pressure service. That's why the material spec is A182—forged stainless and forged Cr-Mo alloy. F316 and F304 for corrosive service at high pressure. F22 and F91 for high-temperature service where you need Cr-Mo alloy strength at 600°F+ operating temperatures. All forged, all defect-free at the pressure ratings where casting can't guarantee integrity. Stellite Overlay — Standard, Not Optional On a flanged swing check at Class 150, Stellite overlay on the seat is optional because the disc impact force at low pressure is manageable. Base metal seating survives. On a butt weld swing check at Class 600+, Stellite overlay on the disc face and seat ring is standard. Here's why: the slamming force increases with pressure rating. At Class 600, the disc hits the seat with significantly more force than at Class 150 because the backpressure driving the disc closure is higher. That higher impact force deforms the base metal seat surface faster—repeated cycling at Class 600+ pounds the seat ring every time the disc closes. Stellite overlay resists that impact deformation. Cobalt-chromium alloy is harder than the base stainless or Cr-Mo steel, and it maintains its surface integrity under repeated high-force disc impact. On a butt weld swing check, you can't easily pull the valve out of the line to re-machine the seat—it's welded in. Stellite overlay from the start means the seat survives for years without seat repair. Welded Cover — When You Need Zero Leak Paths The body cover is the access point for the hinge pin and disc assembly during maintenance. Standard configuration is a bolted cover with a gasket—same leak path concern as any bolted flange joint. For extreme service—high-pressure hydrogen, superheated steam, toxic or flammable gas at Class 900+—a welded cover option eliminates that gasket leak path too. The cover welds to the body, creating a second permanent joint. You lose the ability to open the cover without cutting the weld, but you gain a valve body with no gasket-sealed joints at all. Butt weld ends, welded cover—two potential leak paths eliminated. For the service conditions where even one leak path is unacceptable, that's the configuration to specify. FAQ Disc impact force increases with pressure rating. At Class 600+, the disc slams into the seat with significantly higher force than at Class 150. Base metal seating deforms faster under that impact. Stellite overlay protects the seat surface from repeated high-force closure. Since butt weld checks are typically specified at Class 600+, Stellite comes standard. Not recommended at Class 600+. Casting porosity can leak through the body wall under sustained high pressure. Forged bodies (A182 specification) eliminate internal defects and provide uniform mechanical properties through the wall thickness. At Class 150-300, cast bodies are acceptable; at Class 600 and above, forged is the correct specification. Eliminates the gasket leak path at the cover joint. With butt weld ends and a welded cover, the valve has zero gasket-sealed joints—both end connections and the cover are permanent welds. This is specified for extreme-pressure, high-temperature, or hazardous service where even one gasket leak path is unacceptable. Yes. Swing disc on a hinge pin, gravity closure, 80° maximum opening angle. The disc mechanism is identical. The difference is in the body construction—forged instead of cast, butt weld ends instead of flanged, and Stellite seating as standard instead of optional. Class 150 through 2500 (PN 10-420). The forged body and butt weld construction support pressure ratings that flanged swing checks can't economically or reliably cover. At Class 150-300, flanged and butt weld are both viable; at Class 600+, butt weld becomes the preferred or required configuration.
External Pin Swing Check Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 600 / PN 10-100 Standard: API 6D, ASME B16.34, manufacturer-specific for external pin mechanism Body Materials: A216 WCB, A351 CF8M, A351 CF8 Seat: Metal-to-metal, Stellite overlay optional Disc: Swing disc with external dashpot/pin mechanism—hinge pin extends through the body wall to an external dashpot cylinder mounted on the outside of the valve body. Dashpot contains a hydraulic cylinder or pneumatic chamber that connects to the disc through the extended hinge pin. Dashpot resistance slows disc closing rate—instead of slamming shut instantly, the disc closes gradually over 1-3 seconds. Design: Flanged ends. External dashpot cylinder mounted on body exterior, connected to disc hinge pin through sealed penetration in body wall. Adjustable closing speed—dashpot valve settings control how fast the disc closes. Optional opening assist (air/hydraulic) for disc lifting on low-flow startup. The Slamming Problem — and How the Dashpot Solves It Standard swing check valves slam shut. When forward flow stops, the disc swings back to the seat in a fraction of a second—gravity and backpressure accelerate it, no resistance, no damping. That fast closure generates water hammer. A pressure spike travels back up the pipeline from the sudden disc impact, and that spike can damage pipe supports, burst fittings, crack weld seams, or overload downstream equipment. If you've ever heard a pipe system bang on pump trip, that's water hammer from a slamming check valve. It's not a theoretical risk—it's a real mechanical event that causes real damage, especially on long pipelines where the pressure wave has time to build amplitude. The external pin dashpot eliminates that slamming by slowing the disc closure. The hinge pin extends through the body wall and connects to a hydraulic or pneumatic dashpot cylinder on the outside of the valve. As the disc swings toward the closed position, the dashpot absorbs the closing energy and decelerates the disc to a controlled, gradual seating speed. Instead of slamming shut in 0.1 seconds, the disc closes smoothly over 1-3 seconds. The pressure spike doesn't happen because the disc isn't accelerating into the seat—the dashpot is pulling it down gradually. Water hammer eliminated. Seat impact damage eliminated. The disc reaches the closed position without the violent impact that destroys seat surfaces on standard swing checks over repeated cycling. Adjustable Closing Speed — Tune It to Your Pipeline Not every pipeline needs the same closing speed. A short process line with high backpressure needs the disc to close relatively fast—if the disc takes too long to seat, reverse flow establishes and the pressure drop across the valve reverses before the disc reaches the seat. A long transmission pipeline with low backpressure needs slower closure—water hammer risk increases with pipeline length, and the longer the line, the more energy the pressure wave carries. The dashpot valve settings give you that adjustment range. You tune the closing speed to match the pipeline conditions. Fast enough to prevent reverse flow from establishing. Slow enough to eliminate water hammer. It's a balance, and the adjustable dashpot lets you find it during commissioning instead of guessing during specification. This is the advantage over non-adjustable dampening schemes. Some swing check designs use a counterweight or an internal dashpot with fixed damping—one closing speed, no field adjustment. If the closing speed doesn't match the pipeline, you're stuck. The external pin dashpot is field-adjustable through the dashpot valve settings. Change the setting, change the closing speed. No valve replacement required. Opening Assist — When Flow Velocity Isn't Enough On startup, flow velocity through the pipe starts at zero and ramps up. The disc on a standard swing check starts closed and opens gradually as velocity increases. At low flow velocities—early startup on a large-diameter line, for example—the disc may only open to 30° or 40°. It's partially open, sitting in the flow stream, fluttering as velocity fluctuates. That partial-open flutter causes two problems: seat wear from repeated light contact at partial angles, and disc fatigue from oscillating at the hinge pin. The external pin mechanism offers an opening assist option. Air or hydraulic pressure lifts the disc to full open position on startup before the flow velocity reaches the point where it can push the disc open naturally. The disc goes straight to 80° open. No flutter. No partial-open wear. Once the flow velocity is high enough to hold the disc open on its own, the opening assist releases and the disc stays open by flow force alone. This option matters on large-diameter lines where startup flow velocity is low relative to the disc mass, and on systems with frequent start/stop cycles where the disc passes through the partial-open zone every time the pump starts. The Sealed Penetration — Hinge Pin Through the Body Wall The hinge pin on an external pin swing check penetrates the body wall to connect the disc to the external dashpot. That penetration is a sealed joint—packing or a mechanical seal around the pin where it passes through the body. It's an additional potential leak path compared to a standard swing check where the hinge pin is entirely inside the body. The seal design uses packing compression or O-ring sealing around the pin. Packing adjustment is accessible from outside the dashpot housing—you can re-torque or replace packing without removing the dashpot or disassembling the valve. The penetration seal is maintenance-accessible, and it's the one additional maintenance point that the external pin design requires beyond a standard swing check. It's a trade-off: you gain water hammer elimination and adjustable closing speed, and you accept one sealed penetration that needs periodic packing attention. FAQ Standard swing check closure is roughly 0.1 seconds—near-instant slamming. External pin dashpot slows closure to 1-3 seconds, depending on dashpot settings. That controlled closure eliminates water hammer on most pipeline systems. Yes. The dashpot valve settings control closing speed and are field-adjustable. You tune the speed during commissioning to match your pipeline conditions—faster for high-backpressure short lines, slower for long pipelines with water hammer risk. No valve replacement needed to change closing speed. Opening assist uses air or hydraulic pressure to lift the disc to full open position during low-flow startup, preventing disc flutter at partial-open angles. Specify it on large-diameter lines where startup flow velocity is low relative to disc mass, and on systems with frequent pump start/stop cycles. Yes, it's an additional sealed joint—packing or O-ring around the pin at the body wall penetration. It's maintenance-accessible from outside the dashpot housing and requires periodic packing attention. This is the one additional maintenance trade-off compared to a standard swing check with an internal hinge pin. When water hammer is a real risk—long pipelines, pump trip scenarios, systems where the pressure spike from sudden disc closure can damage pipe supports or equipment. Also when frequent pump cycling causes repeated disc slamming that degrades the seat surface on standard swing checks over time.
Lug Type Dual Plate Check Valve
Quick Specs Size: 2" - 48" (DN50 - DN1200) Pressure: Class 150 - 600 / PN 10-100 Standard: API 6D, ASME B16.34, MSS SP-126 (dual plate check), AWWA C508 (waterworks) Body Materials: A216 WCB, A351 CF8M, A351 CF8, ductile iron (GGG40) Seat: Metal-to-metal or soft seated—dual plate check valves commonly use a combination: metal body seat ring + elastomer or PTFE seal on the plate edge for bubble-tight shutoff. Metal-to-metal plates available for high-temperature service. Plates: Two semicircular plates (half-discs) hinged on a central hinge pin inside the body bore. Plates open by rotating away from the seat surface with forward flow—each plate swings to approximately 60-80° open position. A torsion spring on the hinge pin assists plate closure when forward flow velocity drops. Plates close in a spring-assisted, near-simultaneous motion. Design: Lug body—threaded lug holes on both sides of the body flange. Lug format allows installation between two flanges with bolts through the lug holes, or as a line terminus with one flange blanked off. Short face-to-face dimension (API 6D pattern). Spring-assisted closing. Compact and Fast-Closing — Two Half-Discs Beat One Full Disc The dual plate design splits the check function between two semicircular plates instead of one full-disc swing. Each plate is lighter than a full disc. Each plate swings through a shorter arc to reach the closed position. That lighter mass and shorter travel translate directly to faster closing—roughly 0.2-0.5 seconds with spring assist, compared to 0.5-1.0 seconds for a gravity-closing full-disc swing check. Faster closing means less reverse flow volume passes through the valve before it shuts. On pump discharge protection, that matters. Even a small reverse flow volume can spin the pump backward—reverse rotation causes mechanical damage to the pump impeller, bearings, and shaft. The dual plate check closes fast enough to limit reverse flow to a volume that won't establish sustained reverse rotation. A standard swing check closing in 0.5-1.0 seconds allows more reverse flow through the valve before the disc seats, and on some pump installations that extra volume is enough to start the pump spinning backward. The torsion spring adds closing force beyond gravity. When forward flow velocity drops below the threshold that holds the plates open, the spring drives the plates toward the closed position even if there's no backpressure pushing them shut. That spring assist is essential for vertical installations—flow upward—where gravity doesn't help the plates close. In a vertical pipe, a gravity-closure swing check disc hangs open and relies entirely on reverse flow to push it shut. The dual plate spring closes the plates regardless of orientation. Soft Seated for Bubble-Tight — Metal for High Temperature Dual plate check valves commonly run a hybrid seating arrangement: metal body seat ring with an elastomer or PTFE seal on the plate edge. The metal seat ring provides structural integrity in the body bore. The soft seal on the plate edge compresses against the seat ring when the plates close, creating a bubble-tight shutoff that metal-to-metal seating can't consistently achieve at low backpressure. If your process line needs zero leakage in the closed direction—chemical dosing lines, closed-loop heating systems, applications where even微量 backflow contaminates the upstream process—soft seated dual plates give you that bubble-tight seal under normal backpressure conditions. The elastomer or PTFE seal is replaceable during maintenance without re-machining the seat ring. For high-temperature service where elastomer and PTFE seals degrade—steam above 400°F, hot oil service, fired heater feed lines—metal-to-metal plates are the specification. The plate edge contacts the metal seat ring directly, no soft seal. Shutoff isn't bubble-tight at low backpressure, but the metal seating survives the temperature where soft seals would harden, crack, or lose sealing compression. Lug Body — Dead-End Service and Between-Flanges Installation The lug body has threaded holes on both sides of the body flange. That lug format gives you two installation options that wafer-body check valves don't provide. Option one: dead-end service. Install the valve at the end of a pipeline with one flange blanked off. The threaded lug holes on the blanked side accept bolts that secure the blind flange. Wafer-body check valves can't do this—they have no threaded holes and rely on being sandwiched between two flanges with through-bolts. If you need a check valve at a line terminus, lug is the format that works. Option two: between-flanges installation without a separate spacer ring. The lug body bolts directly to the upstream and downstream flanges with bolts through the threaded lug holes. No spacer. No additional gaskets beyond the two flange-to-valve joints. Simple installation, few components, straightforward bolting pattern. The short face-to-face dimension—API 6D pattern—means the valve occupies less pipeline length than a full-body swing check. On retrofit projects where you're replacing a swing check with a dual plate in an existing pipe run, the shorter face-to-face usually fits within the same pipe spacing without cutting and re-welding the line. The Trade-Off — Slightly Higher Pressure Drop The hinge pin and torsion spring sit inside the body bore on a dual plate check. They occupy space in the flow path. At full open position, the plates swing to 60-80°, but the hinge pin and spring assembly remain in the stream. That's a slightly higher pressure drop than a full-bore swing check where the disc at 80° open leaves the bore nearly unrestricted. For most pump discharge and process line check applications, the pressure drop difference between a dual plate and a swing check at the same size is negligible—a fraction of psi that doesn't materially affect pump performance or process flow rates. On large-diameter, low-velocity lines where pressure drop matters more, or on lines where you're already operating close to the pump's head limit, that difference becomes relevant. In those cases, specify the swing check for minimum pressure drop and accept the slower closing speed. FAQ Roughly 0.2-0.5 seconds with spring assist, versus 0.5-1.0 seconds for a gravity-closure swing check. The two lighter half-discs with shorter swing travel close faster than one full disc relying on gravity alone. Less reverse flow passes through before the valve shuts. Yes. The lug body has threaded holes on both flange sides, allowing dead-end installation with one flange blanked off. Wafer-body check valves can't do this—they require two through-bolts sandwiching the valve between flanges. Soft seated plates have an elastomer or PTFE seal on the plate edge that compresses against the metal body seat ring for bubble-tight shutoff. Metal-to-metal plates contact the seat ring directly—no soft seal—for high-temperature service where elastomers degrade. Soft seats give better sealing at low backpressure; metal seats survive higher temperatures. Yes. The torsion spring drives the plates closed when forward flow velocity drops, regardless of installation orientation. In vertical upward flow, gravity doesn't help close the plates, but the spring provides the closing force. Standard gravity-closure swing checks don't work reliably in this orientation. Slightly higher. The hinge pin and torsion spring sit inside the flow path, creating a small obstruction even at full open position. The difference is typically a fraction of psi aQuick Specs Size: 2" - 48" (DN50 - DN1200) Pressure: Class 150 - 600 / PN 10-100 Standard: API 6D, ASME B16.34, MSS SP-126 (dual plate check), AWWA C508 (waterworks) Body Materials: A216 WCB, A351 CF8M, A351 CF8, ductile iron (GGG40) Seat: Metal-to-metal or soft seated—dual plate check valves commonly use a combination: metal body seat ring + elastomer or PTFE seal on the plate edge for bubble-tight shutoff. Metal-to-metal plates available for high-temperature service. Plates: Two semicircular plates (half-discs) hinged on a central hinge pin inside the body bore. Plates open by rotating away from the seat surface with forward flow—each plate swings to approximately 60-80° open position. A torsion spring on the hinge pin assists plate closure when forward flow velocity drops. Plates close in a spring-assisted, near-simultaneous motion. Design: Lug body—threaded lug holes on both sides of the body flange. Lug format allows installation between two flanges with bolts through the lug holes, or as a line terminus with one flange blanked off. Short face-to-face dimension (API 6D pattern). Spring-assisted closing. Compact and Fast-Closing — Two Half-Discs Beat One Full Disc The dual plate design splits the check function between two semicircular plates instead of one full-disc swing. Each plate is lighter than a full disc. Each plate swings through a shorter arc to reach the closed position. That lighter mass and shorter travel translate directly to faster closing—roughly 0.2-0.5 seconds with spring assist, compared to 0.5-1.0 seconds for a gravity-closing full-disc swing check. Faster closing means less reverse flow volume passes through the valve before it shuts. On pump discharge protection, that matters. Even a small reverse flow volume can spin the pump backward—reverse rotation causes mechanical damage to the pump impeller, bearings, and shaft. The dual plate check closes fast enough to limit reverse flow to a volume that won't establish sustained reverse rotation. A standard swing check closing in 0.5-1.0 seconds allows more reverse flow through the valve before the disc seats, and on some pump installations that extra volume is enough to start the pump spinning backward. The torsion spring adds closing force beyond gravity. When forward flow velocity drops below the threshold that holds the plates open, the spring drives the plates toward the closed position even if there's no backpressure pushing them shut. That spring assist is essential for vertical installations—flow upward—where gravity doesn't help the plates close. In a vertical pipe, a gravity-closure swing check disc hangs open and relies entirely on reverse flow to push it shut. The dual plate spring closes the plates regardless of orientation. Soft Seated for Bubble-Tight — Metal for High Temperature Dual plate check valves commonly run a hybrid seating arrangement: metal body seat ring with an elastomer or PTFE seal on the plate edge. The metal seat ring provides structural integrity in the body bore. The soft seal on the plate edge compresses against the seat ring when the plates close, creating a bubble-tight shutoff that metal-to-metal seating can't consistently achieve at low backpressure. If your process line needs zero leakage in the closed direction—chemical dosing lines, closed-loop heating systems, applications where even微量 backflow contaminates the upstream process—soft seated dual plates give you that bubble-tight seal under normal backpressure conditions. The elastomer or PTFE seal is replaceable during maintenance without re-machining the seat ring. For high-temperature service where elastomer and PTFE seals degrade—steam above 400°F, hot oil service, fired heater feed lines—metal-to-metal plates are the specification. The plate edge contacts the metal seat ring directly, no soft seal. Shutoff isn't bubble-tight at low backpressure, but the metal seating survives the temperature where soft seals would harden, crack, or lose sealing compression. Lug Body — Dead-End Service and Between-Flanges Installation The lug body has threaded holes on both sides of the body flange. That lug format gives you two installation options that wafer-body check valves don't provide. Option one: dead-end service. Install the valve at the end of a pipeline with one flange blanked off. The threaded lug holes on the blanked side accept bolts that secure the blind flange. Wafer-body check valves can't do this—they have no threaded holes and rely on being sandwiched between two flanges with through-bolts. If you need a check valve at a line terminus, lug is the format that works. Option two: between-flanges installation without a separate spacer ring. The lug body bolts directly to the upstream and downstream flanges with bolts through the threaded lug holes. No spacer. No additional gaskets beyond the two flange-to-valve joints. Simple installation, few components, straightforward bolting pattern. The short face-to-face dimension—API 6D pattern—means the valve occupies less pipeline length than a full-body swing check. On retrofit projects where you're replacing a swing check with a dual plate in an existing pipe run, the shorter face-to-face usually fits within the same pipe spacing without cutting and re-welding the line. The Trade-Off — Slightly Higher Pressure Drop The hinge pin and torsion spring sit inside the body bore on a dual plate check. They occupy space in the flow path. At full open position, the plates swing to 60-80°, but the hinge pin and spring assembly remain in the stream. That's a slightly higher pressure drop than a full-bore swing check where the disc at 80° open leaves the bore nearly unrestricted. For most pump discharge and process line check applications, the pressure drop difference between a dual plate and a swing check at the same size is negligible—a fraction of psi that doesn't materially affect pump performance or process flow rates. On large-diameter, low-velocity lines where pressure drop matters more, or on lines where you're already operating close to the pump's head limit, that difference becomes relevant. In those cases, specify the swing check for minimum pressure drop and accept the slower closing speed. FAQ Roughly 0.2-0.5 seconds with spring assist, versus 0.5-1.0 seconds for a gravity-closure swing check. The two lighter half-discs with shorter swing travel close faster than one full disc relying on gravity alone. Less reverse flow passes through before the valve shuts. Yes. The lug body has threaded holes on both flange sides, allowing dead-end installation with one flange blanked off. Wafer-body check valves can't do this—they require two through-bolts sandwiching the valve between flanges. Soft seated plates have an elastomer or PTFE seal on the plate edge that compresses against the metal body seat ring for bubble-tight shutoff. Metal-to-metal plates contact the seat ring directly—no soft seal—for high-temperature service where elastomers degrade. Soft seats give better sealing at low backpressure; metal seats survive higher temperatures. Yes. The torsion spring drives the plates closed when forward flow velocity drops, regardless of installation orientation. In vertical upward flow, gravity doesn't help close the plates, but the spring provides the closing force. Standard gravity-closure swing checks don't work reliably in this orientation. Slightly higher. The hinge pin and torsion spring sit inside the flow path, creating a small obstruction even at full open position. The difference is typically a fraction of psi and negligible for most applications, but it can matter on large-diameter low-velocity lines or systems operating close to pump head limits.nd negligible for most applications, but it can matter on large-diameter low-velocity lines or systems operating close to pump head limits.
Vertical Lift Check Valve
Quick Specs Size: 1/2" - 4" (DN15 - DN100) Pressure: Class 150 - 600 / PN 10-100 Standard: ASME B16.34, MSS SP-80 Body Materials: A216 WCB, A351 CF8M, A182 F316 (forged), bronze/brass for small sizes Seat: Metal-to-metal or soft seated (PTFE/RPTFE disc face against metal seat ring) Disc: Lift disc — vertical lift off seat ring with forward flow, drops back on seat when flow stops Design: Vertical body orientation, flow upward, disc guide sleeve, bolted cover, threaded/socket weld/flanged ends When Closing Speed Actually Matters Here's the thing about check valves most people overlook — the time it takes for the disc to reach the closed position determines how much reverse flow slips through before the valve shuts. On a 2" line at moderate flow velocity, reverse flow volume per second is small. But small-bore systems are often protecting instruments, pump seals, or delicate process connections. Even a few ounces of reverse flow can cause problems. Vertical lift check valves close faster than swing checks because the disc travel distance is short — roughly 1/4 to 1/2 of the pipe diameter. A swing check disc swings through an 80° arc. That arc covers more distance than a vertical lift that simply rises off the seat and drops back down. Shorter travel means the disc reaches the seat faster when forward flow stops. On vertical pump discharge lines and instrument protection risers where you want the valve shut before any meaningful reverse volume passes, that speed advantage is real. The Disc Guide Makes the Difference Swing check discs can drift laterally as they swing — the hinge allows some side-to-side movement, especially at low flow velocities. That drift means the disc might not land perfectly centered on the seat every time. Over thousands of cycles, that imprecision adds up to seat wear and leakage. Vertical lift check valves solve this with a disc guide sleeve inside the body bore. The disc is constrained — it lifts vertically, it drops vertically, and it stays centered on the seat ring throughout both strokes. No lateral drift, no misalignment. That guide precision gives better seat contact than a free-swinging disc, and better seat contact means longer seat life and tighter shutoff. The tradeoff: the disc guide sits inside the flow path and restricts passage area. Vertical lift checks have higher pressure drop than swing checks at the same size. At 1/2" through 2" where the flow area is already limited, that pressure drop is acceptable — you're not moving massive volumes through a 1" line. At 3" and 4", start comparing pressure drop numbers against swing checks or dual plates if flow efficiency matters for your application. Vertical Only — That's the Rule Vertical lift check valves require vertical piping with upward flow. The disc lifts upward with forward flow and drops back down by gravity when flow stops. On a horizontal line, the disc has no gravity assist to close — it would just float. You can't rotate the body and install it horizontally. If your line is horizontal, you need a different check valve type. That installation requirement limits the application scope. But for vertical pump discharge lines, vertical instrument risers, and small-bore vertical process connections where fast closure and positive seating alignment are priorities, the vertical lift check is the right tool. It closes faster than a swing check and seats more precisely. Just make sure your piping runs vertical with flow going up. Metal Seat or Soft Seat — Pick Based on What's Flowing Metal-to-metal seats are standard for steam service and high-temperature applications. The disc face and seat ring are both hard metal — they handle heat, they handle abrasive particles, and they don't degrade from thermal cycling. Leakage tolerance is slightly wider than soft seated versions, but for steam and high-temp process lines, metal seats are the reliable choice. Soft seated versions use a PTFE or RPTFE disc face against a metal seat ring. The soft material compresses into micro-imperfections on the metal surface and gives you bubble-tight shutoff. That matters for water lines, chemical process lines, and any application where even minor leakage is unacceptable. Soft seats don't handle steam or high temperature — PTFE deforms above 450°F. Match the seat material to your service conditions. FAQ A: No. The disc requires gravity to drop back onto the seat when flow stops. On a horizontal line, the disc has no gravity assist. The valve must be installed in vertical piping with upward flow direction. A: The disc travel distance is shorter. A lift disc rises roughly 1/4 to 1/2 of the pipe diameter off the seat, then drops straight back down. A swing disc travels through an 80° arc. Shorter distance means faster arrival at the closed position. A: Vertical lift checks have higher pressure drop. The disc guide mechanism sits inside the flow path and reduces the passage area. At small sizes (1/2"-2"), the difference is acceptable. At 3"-4", evaluate whether the faster closure advantage outweighs the pressure drop penalty for your application. A: Soft seated (PTFE/RPTFE) for water, chemical process, and any application requiring bubble-tight shutoff at temperatures below 450°F. Metal-to-metal for steam, high-temperature service, and applications with abrasive particles in the flow. A: Threaded (NPT/BSP), socket weld, and flanged ends are all available for 1/2" through 2" sizes. Larger sizes (3"-4") are typically flanged. Threaded and socket weld are common for instrument protection and small-bore process connections.
Double Flanged Dual Plate Check Valve
Quick Specs Size: 2" - 48" (DN50 - DN1200) Pressure: Class 150 - 600 / PN 10-100 Standard: API 6D, ASME B16.34, MSS SP-126, AWWA C508 Body Materials: A216 WCB, A351 CF8M, A351 CF8, ductile iron (GGG40) Seat: Metal-to-metal or soft seated (elastomer/PTFE seal on plate edge) Plates: Two semicircular plates on central hinge pin with torsion spring assist Design: Double flanged body — full flanged connections on both inlet and outlet sides (ASME B16.5) Maximum Structural Integrity for Large Lines Wafer and lug dual plate check valves work well for most applications — they sandwich between pipeline flanges and the flange bolts hold everything in position. But at large diameters and high pressures, pipeline forces become serious. A 48" Class 600 wafer body has a thin face-to-face dimension. The body wall between the flanges has minimal structural depth. Under pipeline bending loads, thermal expansion forces, and hydraulic surges at that size and pressure, a wafer body is structurally marginal. Double flanged design solves this by providing full flanged connections on both sides — two independent flange attachment points with a full valve body between them. The structural depth is real. The body resists bending loads from the pipeline. The flanges distribute bolt loading across two dedicated connection surfaces rather than relying on through-bolts clamping a thin wafer. For 24" through 48" lines at Class 300 and above, that structural difference matters. Why You Pay More — and When It's Worth It Double flanged dual plate check valves cost more than wafer and lug formats at the same size. The body is heavier, the face-to-face dimension is longer, and you're buying two full flanges instead of a thin wafer disc. The weight difference is significant at large sizes — a 36" double flanged body weighs considerably more than a 36" wafer body. You pay that premium when structural security matters more than compact installation. Waterworks applications following AWWA C508 often specify double flanged because large-diameter water mains operate under sustained pressure with potential surge events. Petrochemical isolation points on critical pipelines at Class 600 need the structural depth for long-term reliability. If you're running a 6" Class 150 HVAC line, a wafer dual plate does the job at lower cost. If you're running a 36" Class 600 crude oil pipeline, double flanged is the appropriate choice. The Dual Plate Mechanism — Same Proven Design The internal mechanism is the same as lug and wafer dual plate check valves. Two semicircular plates hang on a central hinge pin. Torsion springs on the pin assist plate closing. Forward flow pushes both plates open — the plates fold back against the body wall and leave the bore mostly clear for flow passage. When forward flow stops, the torsion springs start closing the plates immediately, and backpressure finishes the job. Spring assist means the plates begin closing before backpressure develops — faster closure than gravity-only single disc swing checks. Metal-to-metal seats handle steam, high temperature, and abrasive service. Soft seated versions with elastomer or PTFE seals on the plate edge give bubble-tight shutoff for water, chemical, and low-temperature process applications. Same seat options, same closing mechanism — the double flanged format just wraps that proven mechanism in a more robust body. Installation Reality — Longer Face-to-Face, More Bolt Work Double flanged valves have a longer face-to-face dimension than wafer and lug formats. You need more pipe length between the two pipeline flanges to accommodate the valve body. That matters in tight installation spaces — if you're retrofitting a wafer check valve with a double flanged valve, the piping layout may need modification. Bolt work is also more involved. Wafer and lug valves use through-bolts that pass across the valve body. Double flanged valves bolt on each side independently — two sets of flange bolts, two gasket surfaces, two bolt-tightening sequences. More labor per installation. At large sizes where you're handling heavy flanges and long bolts, that labor adds up. FAQ A: At sizes above 24" and pressures Class 300 and above where pipeline structural loads are significant. Also for AWWA C508 waterworks applications and critical petrochemical isolation points where long-term structural reliability matters more than compact installation and lower cost. A: Yes. The full flanges on both sides allow independent bolt-up on each side. You can bolt a blind flange on one side for dead-end isolation. Wafer bodies cannot handle dead-end service because they rely on through-bolts. A: No. The internal flow path and plate mechanism are the same as wafer and lug dual plate check valves. Pressure drop through the valve is determined by the plate geometry and seat design, not the body format. A: Significant at larger sizes. A 24" double flanged body weighs roughly 30-40% more than a 24" wafer body. The difference increases with size. Consider weight in your installation planning — handling equipment, support structures, and freight costs all increase. A: Yes. AWWA C508 covers double flanged check valves for waterworks service. Manufacturers offering double flanged dual plate check valves for water utility applications typically design and test to AWWA C508 requirements.
Axial Flow Check Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 600 / PN 10-100 Standard: ASME B16.34, manufacturer-specific (proprietary design category) Body Materials: A216 WCB, A351 CF8M, A182 F316 (forged for small sizes) Seat: Soft seated (elastomer or PTFE sealing ring on disc face) or metal-to-metal Disc: Axial disc — moves along flow axis, slides upstream to open, slides downstream to close, spring-loaded closing Design: Axial flow geometry, disc recesses into upstream cage when open, full-bore passage, no hinge pin in flow path The Lowest Pressure Drop — By Design Every check valve type puts something in the flow path. Swing checks have a hinge pin crossing the bore. Dual plate checks have a hinge pin and torsion spring mechanism sitting in the passage. Lift checks have a disc guide cage restricting the flow area. All of these obstructions create pressure drop — some small, some significant, but always present. Axial flow check valves eliminate in-line obstructions. The disc moves along the pipe axis — it slides upstream into a cage or recess area when forward flow pushes it open. When the disc is fully open, the full bore is clear. No hinge pin, no spring mechanism, no guide cage crossing the passage. The flow runs straight through an unobstructed bore. Pressure drop is minimal — lower than any other check valve type at the same size. That matters where pressure drop costs real money. Gas compressor discharge lines are the classic example. Compressors are sensitive to discharge backpressure — every psi of additional pressure drop on the discharge side costs energy across every hour of operation. An axial flow check valve on a compressor discharge line adds virtually zero pressure drop. Over years of continuous compressor operation, that efficiency difference accumulates into measurable energy savings. Spring-Loaded Closing — Works Even Without Backpressure Most check valves close by gravity and backpressure. The disc or plates swing or drop when reverse flow pushes them toward the seat. That works on horizontal lines where gravity assists closing and backpressure develops quickly after forward flow stops. But on vertical installations, or in systems where backpressure develops slowly, gravity-only closure is unreliable. Axial flow check valves use a spring to close the disc. The spring pushes the disc downstream onto the seat regardless of whether backpressure exists. The valve closes even at zero differential pressure. That's critical for vertical installations where gravity direction doesn't assist closing, and for low-backpressure systems where reverse flow builds slowly — the spring gets the disc to the seat before significant reverse volume passes through. The spring force is tuned to the valve size and application. Compressor discharge applications use lighter springs to minimize the cracking pressure — the minimum forward flow pressure needed to push the disc off the seat. Pipeline check stations may use heavier springs for faster closure. The spring is part of the design, not an add-on option. Proprietary Designs — Know What You're Buying Axial flow check valves are proprietary. Each manufacturer designs their own disc geometry, cage profile, spring specification, and seat configuration. There's no unified industry standard governing the internal geometry — unlike swing checks (MSS SP-71) or dual plate checks (MSS SP-126) where dimensional and design standards provide interchangeability. That means two things: higher cost relative to standard check valve types, and fewer interchangeable sourcing options. You're buying a specific manufacturer's design, and replacement or alternative sourcing is limited to that manufacturer or a competitor with a similar proprietary design. For critical compressor protection and pipeline check stations where the performance advantage is worth the premium, that's an acceptable tradeoff. For a general-purpose pump discharge line where a standard dual plate check does the job at lower cost, axial flow is over-specified. Full-Bore Passage When Open The disc recesses completely into the upstream cage area when open. The bore is full diameter — the disc doesn't fold against the body wall like dual plate plates, it doesn't swing to one side like a single disc. Flow passes through the full pipe diameter with no reduction. That full-bore passage is what gives axial flow check valves their minimal pressure drop. The tradeoff is body length — the upstream cage area adds face-to-face dimension compared to wafer check valves. Axial flow bodies are longer than wafer dual plate bodies at the same size. FAQ A: Lowest pressure drop. The disc recesses upstream out of the flow path when open, leaving the full bore clear with no obstructions. Every other check valve type has a hinge pin, spring, or guide mechanism in the flow passage that creates additional pressure drop. A: The spring closes the disc onto the seat without relying on backpressure or gravity. The valve shuts even at zero differential pressure. That's essential for vertical installations and low-backpressure systems where gravity and reverse flow alone wouldn't close the disc reliably or quickly enough. A: No. Axial flow is a proprietary design category — each manufacturer has their own internal geometry. Face-to-face dimensions, flange patterns, and external connections follow ASME standards, but the internal mechanism is manufacturer-specific. Sourcing alternatives means finding a different proprietary design with comparable performance. A: Gas compressor discharge protection (where pressure drop directly costs energy), large-diameter pipeline check stations (where continuous pumping energy savings accumulate over years), and vertical installations where spring-loaded closing is necessary. For general pump discharge at moderate sizes, standard check valve types offer adequate performance at lower cost. A: Soft seated is more common. The axial disc geometry provides even circumferential seating contact — the disc presses uniformly against the seat ring around the entire circumference. That uniform contact makes soft seat sealing highly effective. Metal-to-metal is available for hig
Wafer Single Disc Swing Check Valve
Quick Specs Size: 2" - 24" (DN50 - DN600) Pressure: Class 150 - 300 / PN 10-40 Standard: MSS SP-71, API 6D Body Materials: A216 WCB, A351 CF8M, ductile iron (GGG40) Seat: Metal-to-metal or soft seated (elastomer/PTFE seal insert on disc edge or seat ring) Disc: Single disc — full swing on internal hinge pin, up to 80° opening angle, gravity and backpressure closure Design: Wafer body — thin face-to-face, no bolt holes, sandwiches between pipeline flanges with through-bolts The Economy Choice — and What You Give Up Wafer single disc swing check valves are the simplest reverse-flow prevention device you can put between two flanges. Thin body, no bolt holes, one disc on a hinge pin. Forward flow pushes the disc open. Flow stops, gravity and backpressure swing the disc back onto the seat. No spring, no dashpot, no external mechanism, no complicated internals. Just a disc swinging on a pin inside a thin shell. That simplicity makes wafer single disc checks the cheapest swing check format. If you're running a Class 150-300 water line, an HVAC circulation loop, or a general process pump discharge where you need basic reverse-flow protection and cost is the primary decision factor, the wafer single disc is what gets specified. It works. It's affordable. It's available from every valve manufacturer in every common material. But simplicity comes with tradeoffs you need to understand before you install. Dead-End Service — Wafer Can't Do It Wafer bodies have no bolt holes. The valve is held in position by through-bolts that pass across the valve body from one pipeline flange to the other. Both pipeline flanges must be present to clamp the valve. If you need to bolt a blind flange on one side — for dead-end isolation, for a line termination, for maintenance isolation where one side gets blanked off — a wafer body can't do it. There are no bolt holes in the wafer body for a blind flange to attach. You need a lug or double flanged body for dead-end service. This is the most common mistake with wafer check valves. Someone specs a wafer for a pump discharge isolation point, then later wants to blank off the downstream side for pump maintenance. The wafer can't hold a blind flange. The through-bolts that clamp the wafer between the pipeline flanges only work when both flanges are present and bolted. Remove one flange and the wafer has no structural support on that side. Gravity and Backpressure Closure — No Spring Backup The disc closes by gravity and backpressure. No spring assist. On horizontal lines with flow direction that lets gravity pull the disc toward the seat, closure is reliable — the disc swings down by gravity, and backpressure pushes it home. But on vertical lines with upward flow, gravity pulls the disc away from the seat. The disc hangs open unless backpressure develops to push it closed. If backpressure builds slowly — a low-head system, a long discharge line with gradual flow deceleration — the disc stays open longer and more reverse flow passes through before closure. For vertical installations, you need a spring-assisted check valve. Dual plate checks with torsion springs, axial flow checks with spring-loaded discs, or lift checks with short gravity-drop travel all close more reliably on vertical lines. Wafer single disc swing checks are a horizontal-line tool. Thin Body — Less Structural Depth Wafer bodies have minimal face-to-face dimension. That's the design — compact, thin, sandwiched between flanges. At 2" through 6" where pipeline forces are moderate, the thin body handles the loading without issues. At 12" through 24" where pipeline bending loads and thermal expansion forces are substantial, the wafer body has less structural depth than lug or double flanged formats. Less depth means less resistance to bending, less ability to distribute pipeline forces across the body structure. For large-diameter Class 150 water mains where operating pressure is low and surge events are manageable, wafer single disc checks handle the structural requirements. For large-diameter Class 300 process lines or applications with significant pipeline loading, lug or double flanged formats provide more structural security. Metal Seat for Rough Service, Soft Seat for Tight Shutoff Metal-to-metal seats are standard. Disc face against body seat ring — both hard metal surfaces. They handle suspended particles, they handle moderate temperature, they last through thousands of cycles. Leakage tolerance is what you'd expect from metal-on-metal: not bubble-tight, but adequate for most water and general process applications. Soft seated versions add an elastomer or PTFE sealing ring on the disc edge or seat ring surface. The soft material compresses into surface imperfections and gives bubble-tight shutoff. Soft seats work for Class 150-300 water and chemical lines where zero leakage is specified. They don't work for steam or high temperature — elastomer and PTFE degrade above their temperature limits. Match the seat to the service. FAQ A: No. Wafer bodies have no bolt holes — they can only be clamped between two pipeline flanges using through-bolts. For dead-end service or isolation where one side needs a blind flange, use a lug or double flanged body format. A: Not recommended. The disc closes by gravity and backpressure with no spring assist. On vertical lines with upward flow, gravity pulls the disc away from the seat. The valve relies entirely on backpressure to close, which may develop slowly and allow reverse flow to pass before closure. A: Wafer is the lowest-cost format at any given size. The thin body, no bolt holes, and minimal face-to-face dimension reduce material and manufacturing cost. Lug bodies cost roughly 15-25% more. Double flanged bodies cost significantly more, especially at larger sizes. A: Soft seated when bubble-tight shutoff is required at Class 150-300 for water, HVAC, or chemical process lines operating below elastomer/PTFE temperature limits. Metal-to-metal when the service involves suspended particles, moderate-to-high temperature, or where leakage tolerance is acceptable. A: Class 150 and Class 300. Wafer single disc swing check valves are not designed for Class 600 service. The thin body format and gravity-only closure mechanism are appropriate for low-to-moderate pressure applications. Higher pressure and critical service require lug, double flanged, or spring-assisted check valve types.
Technical Overview
Check valves prevent reverse flow in piping systems — they open with forward flow velocity and close when forward flow stops or reverses, protecting pumps, compressors, and process equipment from backflow damage. No external actuation required; the flow itself drives opening and closing through disc weight, spring force, or fluid dynamics. FLOWKS manufactures eight check valve configurations spanning four closing mechanisms and three body formats. Swing check valves use a full disc swinging on a hinge pin — 80° opening angle gives near-full-bore passage and minimal pressure drop, gravity closure, the default for steady-flow pump discharge at 2"-24". Butt weld swing check valves apply forged bodies and butt weld connections at Class 150-2500 where flanged gaskets become reliability liabilities under high-pressure impact slamming. External pin swing check valves add a hydraulic dashpot to the hinge pin — controlled closing over 1-3 seconds eliminates water hammer on pump-trip and long-pipeline applications. Lug type dual plate check valves split the closing motion between two half-discs with torsion spring assist — shorter travel means faster closure (0.2-0.5 seconds), lug format allows dead-end service, compact face-to-face dimension. Vertical lift check valves lift a disc vertically off the seat with upward flow — short travel distance for fast closure at 1/2"-4", disc guide ensures centered seating, vertical-only installation. Double flanged dual plate check valves provide full flanged structural integrity at 2"-48" and Class 600 where wafer/lug bodies lack sufficient pipeline load resistance. Axial flow check valves move the disc along the flow axis into an upstream cage — full-bore open passage with zero obstruction, lowest pressure drop of any check design, spring-loaded closing for zero-backpressure reliability, specified for compressor discharge and continuous-flow pipeline stations. Wafer single disc swing check valves deliver economy swing check protection at Class 150-300 in thin wafer format — simplest, cheapest, basic reverse-flow prevention for water, HVAC, and general process lines.
FLOWKS check valves provide automatic reverse-flow prevention across the full range of industrial piping sizes and pressures. Swing check valves deliver near-full-bore passage with 80° disc opening and gravity closure — the default for steady-flow pump discharge at 2"-24" Class 150-600. Butt weld swing check valves with forged bodies eliminate flanged connections at Class 150-2500 where gaskets leak under high-pressure disc impact slamming. External pin swing check valves add hydraulic dashpot control for 1-3 second gradual closure that eliminates water hammer on pump-trip and long-pipeline applications. Lug type dual plate check valves close faster with two spring-assisted half-discs — 0.2-0.5 second closure, dead-end service capability, compact face-to-face dimension at 2"-48". Vertical lift check valves provide fast guided closure on small-bore vertical lines at 1/2"-4" where disc alignment precision matters. Double flanged dual plate check valves deliver maximum structural integrity at 2"-48" Class 600 for waterworks and critical pipeline stations. Axial flow check valves offer the lowest pressure drop with full-bore unobstructed passage and spring-loaded closing — compressor discharge and continuous-flow pipeline protection. Wafer single disc swing check valves give economy reverse-flow prevention at Class 150-300 in compact wafer format for water and HVAC service.
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Industries Using Check Valves
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Oil & Gas
Upstream, midstream and downstream valve solutions meeting API 6D, API 607 fire-safe requirements. From wellhead to refinery, FLOWKS provides reliable valve solutions for the most demanding oil and gas applications.
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.
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.
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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.