Check Valves | Types | Industry codes and Standards

Check Valves

A Check valve is used to stop the reversal of flow in a piping system.

check valves

Check valves are available in the following designs :

• Swing Check Valves
• Tilting Disk Check Valves
• Lift Check Valves
  • Disk Check
  • Piston Check
  • Ball Check
• Duo-Check Valves

Swing Check Valves are available in straight body design and y-pattern design. The disk is suspended from the body by means of a hinge pin and seals against the seat which is integral to the body. These valves are typically used in sizes 2 inches and over. Swing check valves can be installed in both horizontal and vertical positions. They are not suitable for pulsating flow.
The closure response of the swing check valve is slower compared to the lift check valve due to longer disc travel and inertia of the disk.

Swing check valves

Tilting Disk Check Valves fit between two flanges and provide a compact installation for large diameter applications. These valves can be installed in horizontal and vertical lines. They provide a faster closing response and are particularly suited for pulsating flows with compressible fluids.

Lift Check Valves are available in the disk, piston, and ball type design. Some designs use spring to return the closure member to the seating position. These valves are used in smaller sizes, generally below 2 inches. These types of valves have a higher resistance to flow. Y-type designs are available with lower pressure drops across the valve. The spring-loaded design can be used in both horizontal and vertical positions. Without the spring-  loading this design must not be used in a vertical position.
The closure response of check valves is relatively fast due to shorter lift and low inertia of closing member.

Dual Check Valves have two disks and rely on internal spring loading for closure.

Check valves are extremely sensitive to an upstream piping configuration such as bends, valves. It is recommended that check valves be placed at least 3 pipe diameters away from such obstruction.

Industry Codes and Standards

• API 6D - Specification for Pipeline valves
• BS 5152 - Cast Iron globe and globe stop and check valves (withdrawn)
• BS 5352 - Cast and forged steel gate, globe, check and plug valves, screwed and socket welding ends (<= 50mm)
• BS 1868 - Specification for steel check valves (flanged and butt-welding ends)
• MSS SP 61 - Pressure testing of steel valves
• MSS SP 25 - Standard marking system for valves, fittings, flanges & unions
• MSS SP 45 - Bypass and drain connections