Swing Check Valve

The swing check valve is a type of check valve that allows fluid to flow in one direction and prevents backflow. The valve has a disc that swings on a hinge or trunnion. When the fluid flows forward, it pushes the disc open; when the flow reverses, the disc swings back to seal against the seat and stop reverse flow.
Swing check valves are simple, reliable one-way valves suitable for many industries.
Advantages: Low-pressure drop, easy installation, minimal maintenance.
Limitations: Can be slow to close in some designs, risk of water hammer if flow is sudden.

1.Structure of Swing Check Valve

The main components of a swing check valve are:
Body – The outer casing of the valve, typically made from cast iron, ductile iron, carbon steel, stainless steel, or alloy steel.
Bonnet – Covers the internal parts and provides access for maintenance.
Disc/Clapper – Moves freely on a hinge; swings to allow forward flow and closes to prevent backflow.
Hinge/Trunnion Pin – Supports the disc and allows it to pivot.
Seat – The surface against which the disc seals to prevent reverse flow; can be metal-to-metal or soft-seated.
Hinge Pin Retainer/Stop – Prevents the disc from swinging too far.
Flow direction: Usually marked with an arrow on the body.
Types:
Horizontal swing check valve – installed in horizontal pipelines.
Vertical swing check valve – installed in vertical pipelines, requires upward flow.

2. Standards of Swing Check Valve

Common standards for swing check valves include:
API 6D – for pipeline applications.
API 594 – check valve standard.
ASME B16.34 – valve design and pressure rating.
ISO 9001 – manufacturing quality management.
BS 1868 / EN 12334 – European and British standards.

3. Features of Swing Check Valve

Simple and reliable design.
Low pressure drop in forward flow.
Disc swings open fully for unobstructed flow.
Can be installed in horizontal or vertical pipelines (depending on design).
Metal-to-metal or soft-seated options available for tight sealing.
Minimal maintenance if installed correctly.

4. Applications of Swing Check Valve

Swing check valves are widely used in:
Water and wastewater systems.
Steam and condensate lines.
Oil and gas pipelines.
Chemical and petrochemical industries.
HVAC systems and pumps (to prevent backflow).
Typical uses: Protecting pumps, compressors, and turbines from reverse flow damage.
5. Operation manual of Swing Check Valve
Forward Flow: Fluid enters the valve, lifts the disc off the seat, and flows through freely.
Reverse Flow: When flow stops or reverses, the disc swings back onto the seat, creating a tight seal and stopping backflow.
Key points:
Valve must be installed according to flow direction.
Avoid water hammer by ensuring proper sizing and flow conditions.

6. Maintenance Manual of Swing Check Valve

Routine Maintenance Tips:
Inspection:Check for leakage around the seat.
Inspect disc, hinge, and body for wear or corrosion.
Cleaning:Remove debris that may prevent disc from closing properly.
Clean seats and disc surfaces.
Lubrication:Typically not required for swing check valves, unless manufacturer specifies.
Disassembly:Shut down the system and relieve pressure.
Remove the bonnet to access disc and hinge.
Replace worn seats or hinges.
Reassembly and Testing:Ensure disc swings freely.
Test under pressure before returning to service.
Periodic Testing:Monitor for noise, water hammer, or reverse flow to ensure proper operation.