I. Visual Inspection
Rust: Reddish-brown spots or powdery substances appear on the surface; in severe cases, peeling may occur.
Cracks/Deformation: Check the flange cover body for casting or machining defects such as cracks or sand holes.
Burnt/Indentation: Indentations or thread defects on the hexagonal face or flange bottom surface.
II. Sealing Performance Inspection
Media Leakage: Leaks detected during pressure testing or operation must be addressed immediately.
Pressure Testing: Apply pressure using specialized equipment and observe for leaks.
III. Bolt Torque Inspection
Uneven Torque: Measure bolt torque using specialized tools. Loose bolts may indicate a weak connection due to corrosion.
Signs of Loosening: Bolt loosening worsens during operation, potentially posing a safety hazard.
IV. Operating Sound Inspection
Abnormal Sounds: Listen to the connection points during operation. Friction or impact sounds may indicate corrosion causing problems with component fit.
V. Temperature Change Inspection
Overheating: Use an infrared thermometer to check the temperature of the flange nut and its surrounding area. An abnormally high temperature may indicate internal friction or sealing leakage due to corrosion.
VI. Specifications and Standards
Exposed Bolt Length: According to standards such as GB50235-2019, bolts should protrude 1-3 threads from the nut after tightening. Corrosion may result in insufficient length.
Corrosion Protection Requirements: Confirm that the anti-corrosion measures for bolts, nuts, and washers are adequate. Corrosion may indicate anti-corrosion failure.
VII. Treatment Recommendations
Timely Replacement: If corrosion is severe, it is recommended to replace the flange nut to avoid safety hazards.
Corrosion Protection Treatment: Apply anti-corrosion treatment to uncorroded areas to extend service life.
Regular Inspection: Establish an inspection cycle based on operating conditions to promptly detect and address corrosion problems.
