Flange selection must meet the design requirements. When the design does not require, should be in accordance with the system of high working pressure, high working temperature, working medium, flange material grade and other factors comprehensive selection of appropriate form and specifications of the flange.
Flange must be inspected before installation, the surface should be smooth, there shall be no sand holes, cracks, spots, burrs and other defects that reduce the strength of the flange, and there shall be no penetrating scratches and other defects affecting the sealing on the sealing surface.
When assembling flanges and pipes, use flange ruler to check the verticality of flanges. When the flange connection parallel deviation size is not specified in the design, it should not be greater than 1, 5% of the flange diameter, and not more than 2mm, when the two flanges are not parallel and exceed the requirements of the specification must be straightened, do not use multiple gaskets to correct.
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.