Flange technology requirements
The selection of flanges must meet the design requirements. When there is no requirement in the design, flanges of appropriate form and specifications should be selected comprehensively according to the system's maximum working pressure, maximum working temperature, working medium, flange material designation and other factors.
Flanges must be visually inspected before installation. The surface should be smooth and free of blisters, cracks, spots, burrs and other defects that reduce the strength of the flange, and there should be no penetrating scratches on the sealing surface that affect the sealing performance.
When assembling the flange and the pipe, use a flange bending rule to check the verticality of the flange. When the design of the parallel deviation dimension of the flange connection is not specified, it should not be greater than 1,5% of the outer diameter of the flange, and not greater than 2mm. When the two flanges are not parallel and exceed the specified requirements, they must be trimmed. A shim is corrected.
When the flange is welded to the pipeline, it should be welded on both sides according to the standard, and the height of the welding foot should meet the requirements.