I. Visual Inspection
Flange Surface: Check for scratches, burrs, or corrosion.
Bolts and Nuts: Confirm that the bolts protrude 1-3 threads above the nut and that the nuts are not loose.
II. Sealing Surface Inspection
Flatness: Measure the gap with a feeler gauge to ensure the gasket is not misaligned.
Gasket Condition: Check for wrinkles or incorrect installation.
III. Alignment Inspection
Flange Alignment: Deviation should not exceed 1.5% of the outer diameter (maximum 2mm).
Bolt Hole Alignment: Center deviation should not exceed 5% of the hole diameter.
IV. Tightening Inspection
Torque: A torque wrench is required for high-temperature and high-pressure systems.
Sequence: Tighten in stages diagonally.
V. Corrosion Protection Inspection
Surface Treatment: Confirm that the bolts, nuts, and gaskets meet corrosion protection requirements.
VI. Tools and Specifications
Tools: Use a torque wrench for high-temperature and high-pressure systems; use a box wrench for general equipment.
Specifications: Refer to standards such as GB50235-2019.
