--- title: "Check Valve Sizing & Application Guide: Types, Cracking Pressure & Selection" date: 2026-08-07T09:24:00Z modified: 2026-08-25T09:45:06Z permalink: "https://www.tgvalve.com/blog/check-valve/check-valve-sizing-and-application-guide/" type: post status: publish excerpt: "" wpid: 2970 categories: - Check Valve featured_image: "https://www.tgvalve.com/wp-content/uploads/2026/08/check-valve-sizing-and-application-guide-featured.webp" featured_image_alt: Check Valve Check Valve Sizing & Application Guide - featured timestamp: 2026-08-25T09:45:06Z tags: - Check Valve --- ## Quick Answer: A Guide to Sizing Check Valves and Application. Check valve sizing requires matching valve type, cracking pressure, and flow velocity to prevent backflow and slam in water, oil, gas, and steam systems. An API 594 check valve prevents backflow automatically, using the process fluid’s pressure to open and close. TG Valve’s flanged SS316 lift check valves and full port [swing check valve](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/post/dual-plate-vs-swing-check-valve.md)s are engineered to API 594 and ASME B16.34. Their cracking pressures are as low as 0.5 psi for low-flow lines. TG Valve tests every valve to API 598. The company has supplied check valves to buyers in over 40 countries with full material traceability. ## What Does an API 594 Check Valve Do? An API 594 check valve stops backflow without any manual operation or external power source. It allows flow in only one direction and automatically closes. It is also known as a non-return or one-way valve. In piping systems, backflow can damage pumps, contaminate products, or drain elevated tanks. This valve design opens when forward flow pressure exceeds the closing force. Then it shuts down when flow reverses. This automatic action protects equipment upstream and downstream without relying on an operator or actuator. ## How Does a Check Valve Work? ![Check Valve Check Valve Sizing & Application Guide diagram](https://www.tgvalve.com/wp-content/uploads/2026/08/check-valve-sizing-and-application-guide-img1-2.webp "Check Valve - image 2") The check valve’s, or one-way valve’s, basic operating procedure works by using its fluid’s pressure and flow direction to open and close. This is because it does not rely on manual operation, does not have an actuator, solenoid, or handwheel. Forward flow pushes the closing element (disc, ball, or plate) and opens it against a spring or gravity mechanism. But when flow slows down or reverses, the closing element returns to its seat. The closing motion’s speed determines whether the valve closes gently or slams shut. ## What Are the Main Types of Check or One-Way Valves? There are six main check valve types. These cover most industrial piping applications, each recommended for different flow conditions. A swing check valve has a hinged disc that swings open with flow and closes when the flow is reversed. A life check valve has a piston-guided disc that lifts straight up. This is similar to a globe valve body. A dual-plate check valve has two spring-loaded half-discs that close faster than a single swing disc. A [tilting disc check valve](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/post/tilting-disc-check-valve-principle-application.md) has a disc that pivots on a center trunnion for balanced, low-slam closure. A ball one-way valve has a free-floating ball that seats under reverse flow. This is commonly used in slurry service. A stop one-way valve combines the check function with a manual override for steam isolation. ## Why Is Cracking Pressure Critical to Check the Valve Design? [Check valve cracking pressure](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/post/check-valve-cracking-pressure-guide.md) is critical in checking valve design because of the minimum upstream pressure required to lift off the disc. However, make sure that the cracking pressure is not too high or too low. A cracking pressure set too low may result in chatter where the disc bounces against the seat under low, unstable flow. Meanwhile, a setting that is too high causes unnecessary back pressure and wastes pump energy. Most water and oil check valves crack between 0.5 and 5 psi; steam service often requires a higher setting. Match the check valve cracking pressure to the system’s minimum flow rate to keep the disc fully open under normal operation. ## How Do You Size a Check or One-Way Valve? ![Check Valve Check Valve Sizing & Application Guide diagram](https://www.tgvalve.com/wp-content/uploads/2026/08/check-valve-sizing-and-application-guide-img2-2.webp "Check Valve - image 3") Check valve sizing requires matching the valve to the flow rate and velocity so the disc stays fully lifted at normal and maximum flow. Proper sizing also requires keeping the pressure drop acceptable to avoid chatter or slam. ### Step 1: Gather Process Data Collect data such as fluid type and specific gravity, flow rates, operating pressure and temperature, and pipe size and layout. ### Step 2: Choose the Valve Type First Different types have different minimum velocities and Cv characteristics. A swing check valve requires enough velocity to fully lift the flapper. A silent or spring-loaded valve, such as a lift check valve, often requires a lower minimum velocity. The type affects the required size for the same line. ### Step 3: Check Velocity and Minimum Lift Requirement Manufacturers usually specify a minimum velocity to keep the disc fully open. The typical range is ~0.6-1.2 m/s for water. However, check the manufacturer’s spec sheets for verification. Calculate the average velocity at normal flow using this formula: ![Check Valve Check Valve Sizing & Application Guide diagram](https://www.tgvalve.com/wp-content/uploads/2026/08/check-valve-sizing-and-application-guide-img3-2.webp "Check Valve - image 4") Compare the results with the manufacturer’s minimum velocity for full lift for that valve type and size. Ensure that at the minimum expected flow, the velocity is still high enough to avoid disc “hunting,” which causes wear and noise. ### Step 4: Use Flow Coefficient (Cv) to Confirm Pressure Drop Manufacturers provide a recommended Cv (or Kv) for each size/type. Cv is defined as the flow of 60°F water (GPM) that passes with a 1 psi pressure drop. Decide on an allowable pressure drop for the one-way valve at normal flow. ### Step 5: Verify Across All Flow Conditions Check the selected valve based on minimum flow, normal flow, and maximum flow. - Minimum flow: disc still adequately lifted; no excessive chatter. - Normal flow: pressure drop within budget; velocity in recommended range. - Maximum flow: pressure drop still acceptable; no excessive noise or cavitation risk. If the valve is only properly sized at a specific flow but misbehaves at min or max, adjust size or type. ### Step 6: Consider Installation and Piping Effects Before installation, provide the recommended straight runs for upstream/downstream to reduce turbulence and disc instability. Ensure that the orientation is correct. Avoid placing the valve too close to pumps, elbows, or other disturbances unless allowed by the manufacturer. ## Why Does a Non-Slam Design Matter? A [non-slam check valve](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/post/non-slam-check-valve-guide.md) design matters because it is slow enough to avoid water hammer, yet fast enough to stop reverse flow. Water hammer occurs when a one-way valve slams shut against a sudden flow reversal. This action sends a pressure spike through the pipeline. Repeated slam events fatigue pipe joints, gaskets, and valve internals over time. Dual plate and tilting disc valves close faster than standard swing designs, shortening the reversal window before slam. Spring-assisted closure shortens that window further in pump discharge and multi-pump header applications. ## What Materials Are Check Valves Made From? Check valve materials are made from compatible materials for the process fluid and its pressure-temperature range. - Cast iron: economical choice for low-pressure water and general utility service. - Carbon steel handles higher pressure and temperature in oil and gas piping. - SS316: resists corrosion in chemical, marine, and food-grade process lines. - Bronze: common in smaller water service lines and marine plumbing systems. ## What Standards Govern One-Way Valve Design and Testing? Three standards define most industrial valve requirements: API 594, API 6D, and ASME B16.34. 1. API 594 covers wafer and [flanged check valve](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/post/types-of-flanged-check-valve.md) design, dimensions, and testing specific to valves. 2. API 6D applies to pipeline valves generally, including check valves used in transmission service. 3. ASME B16.34 sets pressure-temperature ratings for the valve body material and class. Buyers should confirm which standard a supplier tests to, since certification scope varies by manufacturer. ## What Are Best Practices for Check Valve Installation? Check valve installation requires correct orientation and flow direction to function as designed. - Swing check valves are installed horizontally or in vertical upflow lines, depending on the hinge design. - Lift check valves require horizontal installation, since their guided disc relies on gravity to reseat. Always check the arrow cast in the valve body, which marks the flow direction. Reversing it prevents the valve from sealing. Straight pipe runs upstream and downstream reduce turbulence that can cause premature disc wear. ## How Do You Select a Check or One-Way Valve by Application? Check valve selection depends on the media, pressure class, and slam risk of the specific application. - Water and wastewater: swing or dual-plate valves in cast iron or ductile iron bodies. - Oil and gas valve solutions: lift or dual-plate valves in carbon steel, rated to API 6D. - Chemical processing solutions: SS316 lift or ball check valves for corrosion resistance. - Steam systems: stop check valves or tilting disc valves rated for high temperature. ## What Causes Valve Failure? Most check valve failures trace back to a sizing or selection mistake, not a manufacturing defect. - Chatter from an oversized valve or a cracking pressure set too low for the flow rate. - Water hammer from a slow-closing valve in high-velocity reversal service. - Seat leakage from disc wear, debris, or an incompatible seat material. - Sticking from corrosion buildup or an undersized valve running below minimum velocity. ## How Do the Main Types Compare? This table compares slam risk, orientation, and typical application across the six main types. | **Type** | **Slam Risk** | **Orientation** | **Typical Cracking Pressure** | **Best-Fit Application** | | --- | --- | --- | --- | --- | | **Swing check valve** | Moderate to high | Horizontal or vertical upflow | 0.1-1 psi | Water, wastewater | | **Lift check valve** | Low to moderate | Horizontal only | 1-5 psi | Oil and gas, chemical | | **Dual plate check valve** | Low | Horizontal or vertical | 0.5-2 psi | High-pressure water, oil and gas | | **Tilting disc check valve** | Low | Horizontal or vertical | 0.3-1.5 psi | Steam, high-velocity service | | Ball one-way valve | Low | Horizontal or vertical | 0.5-3 psi | Slurry, viscous media | | Stop one-way valve | Low (manual override) | Horizontal | Set by operator | Steam isolation | ## Why Choose TG Valve for Valve Sizing and Selection? Choosing TG Valve as your manufacturing partner ensures that all valves are sized based on your system’s specifications. Flanged SS316 Lift Check Valves manufactured by TG Valve come in a guided-disc configuration tested according to ASME B16.34 standards. TG Valve’s flanged SS316 lift check valves use a guided-disc design rated to ASME B16.34, Class 150 through Class 600. Our full port swing check valves pass API 598 seat and shell testing before shipment. Every valve ships with a mill test report and material certification for full traceability. We have supplied one-way valves to water treatment, oil and gas, and chemical processing buyers across more than 40 countries. Hero Product Highlight [ ![Full Port Double Flange Swing Check Valve](https://www.tgvalve.com/wp-content/uploads/2025/06/Swing-check-valve-1.jpg) Full Port Double Flange Swing Check Valve **Body and Ball:** Carbon Stainless, Stainless Steel, Ductile Iron **Seals:** Soft Seal, Metal to Metal **Design and Manufacturing Standards:** API 6D/API 594/ASME B16.34/BS 1868 View Product ](https://www.tgvalve.com/product/full-port-double-flange-swing-check-valve/)## Frequently Asked Questions ### We’re replacing an old swing check valve that chatters on a boiler feed line. What should we check first? First, check the cracking pressure rating and compare it with your minimum flow condition. If the old valve chattered at low flow, a dual plate or tilting disc design with a higher-rated cracking pressure usually solves it. ### Can I install a lift check valve vertically? No. Standard lift check valves require horizontal installation because the disc relies on gravity to reseat. For vertical lines, ask for a spring-loaded lift design, or switch to a swing or dual-plate valve rated for vertical upflow. ### How do I know if my valve is causing water hammer in a multi-pump station? Listen for a bang when a pump shuts down, or another pump takes over the header. That is usually a swing check slamming shut. A spring-assisted dual-plate or tilting disc valve at each pump discharge typically fixes it. [Get Free Quote](https://www.tgvalve.com/wp-content/uploads/wp-mfa-exports/page/contact.md)