Check Valve

Overview

The swing-type check valve is a non-return valve designed to allow fluid flow in one direction while automatically preventing backflow. The disc swings on a hinge pin mounted in the valve body, opening under forward flow pressure and closing by gravity and reverse pressure when flow stops or reverses. This simple, reliable mechanism requires no external actuation and provides low pressure drop across the valve.

Swing Disc Mechanism

The swing disc is pivoted at the top of the valve body and swings freely through an arc. Under normal forward flow, the disc swings fully open, minimising flow resistance. When flow ceases or reverses, the disc swings back to seat against the body seating face, creating a tight shut-off and preventing backflow. The disc and seat are precision-machined to ensure reliable sealing across the full pressure range.

Body Materials

Check valves are available in a range of body materials to suit different media and service conditions:

• Cast Iron (GG25) – cost-effective option for water and non-corrosive media at moderate pressures
• Ductile Iron (GGG40/50) – higher strength and impact resistance, suitable for water supply and wastewater applications
• Stainless Steel (CF8M / 316SS) – excellent corrosion resistance for steam, oil, gas, and aggressive chemical media

End Connections & Size Range

Flanged end connections conform to ANSI, DIN, and JIS drilling patterns, enabling direct bolt-up to standard pipework flanges without adapters. The valve is available in nominal bore sizes from 1/2" (DN15) through 24" (DN600), covering the full range of industrial pipeline requirements.

Pressure Ratings

Pressure ratings span PN16 to PN40 (Class 150 to Class 300 ANSI equivalent), accommodating low- to high-pressure pipeline systems. The appropriate pressure class should be selected based on the maximum allowable operating pressure and temperature of the service.

Standards Compliance

These check valves are designed and tested in accordance with internationally recognised standards:

• ANSI/ASME B16.34 – Valves – Flanged, Threaded, and Welding End
• DIN EN 12334 – Industrial valves; cast iron check valves
• JIS B2071 – Cast iron check valves for general use
• API 594 – Check Valves: Flanged, Lug, Wafer, and Butt-welding

Typical Applications

Swing check valves are widely used across industrial and municipal sectors:

• Water supply and distribution networks
• Steam and condensate return lines
• Crude oil and refined petroleum product pipelines
• Natural gas and LPG transmission and distribution
• HVAC and fire protection systems
• Chemical and process plant pipework

Installation Notes

Swing check valves must be installed in horizontal pipelines or in vertical pipelines with upward flow only, to ensure the disc closes reliably under gravity. The valve should be installed with the flow arrow on the body aligned with the direction of intended flow. Adequate straight pipe runs upstream and downstream are recommended to minimise turbulence effects on disc seating.

Maintenance

Swing check valves are largely maintenance-free under normal operating conditions. Periodic inspection should include checking for seat leakage, disc hinge pin wear, and body corrosion. The bolted bonnet design allows in-line inspection and disc replacement without removing the valve body from the pipeline. Replacement seat rings and disc assemblies are available as spare parts.