AWWA C518 is a standard for dual-disc swing check valves developed by the American Water Engineers Association (AWWA). Its full name is "ANSI/AWWA C518 Dual-Disc Swing Check Valves for Water Supply Systems". It is applicable to raw water, drinking water and reclaimed water systems with a diameter of 2 inches to 48 inches (50 mm to 1,200 mm) and specifies the minimum technical specifications for valves in terms of materials, structure, pressure rating, sealing performance and testing requirements.
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AWWA C518 Specifications
| Parameters | Technical Details | Remarks |
| Standard Specification | AWWA C518 | Standard for Dual-Disc Spring-Loaded Check Valves. |
| Nominal Size Range | 2" - 48" (DN50 - DN1200) | Larger sizes (up to 72") available upon request. |
| Rated Working Pressure | 150 psi, 250 psi | Depending on material and application requirements. |
| Connection Types | Wafer, Lug, Double Flanged | Wafer type is the most common industry standard. |
| Face-to-Face Dimension | Per API 594 / AWWA C518 | Ultra-short design for reduced weight and space. |
| Hydrostatic Shell Test | 1.5 x Rated Pressure | Ensures structural and pressure integrity. |
| Resilient Seat Test | 1.1 x Rated Pressure | Guarantees "Bubble-Tight" shut-off. |
| Service Media | Potable Water, Raw Water, Clean Water | Suitable for municipal and industrial water systems. |
AWWA C518 Materials of Construction
| Component / Part Name | Common Materials | Material Specification / ASTM Standard |
| Valve Body | Ductile Iron / Gray Iron | ASTM A536 / ASTM A126 Cl. B |
| Dual Discs (Plates) | Bronze / Stainless Steel / Ductile Iron | ASTM B584 / ASTM A351 CF8M |
| Resilient Seating | EPDM / NBR (Buna-N) / Viton | Ensures a zero-leakage seal. |
| Torsion Springs | Stainless Steel 302 / 316 / Inconel | Provides rapid closing force to prevent surge. |
| Hinge & Stop Pins | Stainless Steel 304 / 316 / 410 | Supports disc rotation and travel limit. |
| Bearings / Bushings | PTFE / Bronze | Reduces friction and prevents pin seizing. |
| Protective Coating | Fusion Bonded Epoxy (FBE) | Compliant with AWWA C550 for corrosion protection. |
| Hardware / Fasteners | Stainless Steel | Superior resistance to oxidation and rust. |
Why Choose AWWA C518? (Comparison with Traditional Check Valves)
| Pain Points / Engineering Challenges | Traditional Swing Check (AWWA C508) | Dual-Disc Spring-Loaded (AWWA C518) |
| Water Hammer (Slam) | Slow Closing: Only closes after backflow has already initiated, causing massive hydraulic shock and "pipe slam." | Rapid Closure: Snaps shut before backflow begins, ensuring silent and slam-free operation. |
| Installation Space | Bulky: Long face-to-face dimensions and heavy weight require a large footprint. | Ultra-Compact: Typically only 1/4 to 1/8 the face-to-face length of traditional valves. |
| Installation Orientation | Limited: Generally restricted to horizontal pipelines only. | Versatile: Suitable for both horizontal and vertical (upward flow) installations. |
| Maintenance Costs | Complex: Many internal moving parts; hinge pins and bushings are prone to premature wear. | Simplified: Streamlined design with high-grade springs and pins for long-term durability and minimal maintenance. |
Applications of AWWA Valve
Municipal Water Pumping Stations
Pump Discharge
Silent Operation
High-Rise Building Water Systems
Vertical Installation
HVAC Systems
Water Treatment & Industrial Processes
Filter backwashing system
Seawater desalination and raw water transportation
Industrial circulating cooling water
GNEE AWWA Valve factory
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FAQ
What are AWWA valves?
AWWA valves are designed to meet rigorous American Water Works Association (AWWA) standards, ensuring durability and reliability in water distribution and treatment systems. Engineered for long service life, these valves are optimized for municipal, industrial, and commercial water infrastructure.
How should a swing check valve be installed?
Swing check valves are always installed with the HINGE PIN placed horizontally, and above the pipe centerline (as shown in the pictures at the end of this section). Incorrect installation may result in binding, high head loss, and/or sticking in the open position.