Flange check valves are essential components in pipeline systems, designed to prevent medium backflow. Proper installation and maintenance are critical for optimal performance. Below are key technical points:

Installation Essentials

1. Positioning

   • Install vertically with the valve bonnet facing upward (except for horizontal swing-type designs).

   • Ensure 5x pipe diameter of straight upstream/downstream sections for laminar flow.

2. Flange Connection

   • Use PN10/PN16 standard flanges (per GB/T 9119).

   • Align gaskets properly and tighten bolts crosswise in 3 stages (30%-70%-100% torque).

3. Flow Direction

   • Arrow markings on valve body must match medium flow direction.

   • Verify disc movement is unobstructed before pressure testing.

4. Sealing Integrity

   • Apply graphite spiral-wound gaskets for high-temperature/pressure applications.

   • Conduct helium leak test if handling hazardous media.

Maintenance Protocol

1. Routine Inspection

   • Quarterly checks for:
     ✓ Disc movement (should swing freely)
     ✓ Seal leakage (<0.1% of rated flow)
     ✓ Bolt tension (retorque if loosening exceeds 10%)

2. Cleaning

   • Flush with clean water/compressed air every 6 months.

   • Remove debris from seat ring and disc guide rails using nylon brushes.

3. Lubrication

   • For swing-type valves: Apply food-grade silicone grease to hinge pins annually.

   • For lift-type valves: Lubricate stem threads with EP2 lithium grease.