Inspection of Flange Fasteners
2022-09-28
Gasket: during installation, ensure that the gasket is new and clean and dry, and check whether the gasket is defective or damaged; the old gasket cannot be reused; before installation, confirm that the size and grade of the gasket used are consistent with the flange identification.
Flange: Before installation, check whether the flange surface is damaged, such as scratches, nicks, mud, corrosion and burrs. When the depth of dents and scratches radially passing through the water lines of the flange sealing surface exceeds 0.2mm, and the coverage exceeds half of the width of the gasket sealing surface, the flange must be replaced or the sealing surface must be reprocessed and repaired. The position of the nut supporting surface on the back of the flange should be parallel and smooth. Check whether the flange is aligned, the inspection method shall be in accordance with the installation requirements of the pipe 6.2 in the SH3501-2011.
Bolts and nuts: check whether the bolts and nuts are used correctly according to the design requirements of equipment and pipelines; the threads and contact surfaces shall be free of dirt, rust, heavy skin, nicks, burrs, chips and other external substances that affect the torque during the tightening process;
It is not allowed to repair the bolt by welding or machining. After the flange is installed and tightened, at least two threads are exposed outside the nut. The bolt and nut must be lubricated before use to make the bolt have a low friction coefficient and improve the anti-sliding and anti-corrosion performance of the bolt and nut. The stud thread, nut thread and contact surface must be degreased and dried before applying lubricating oil;
Uniform lubricating oil shall be properly applied to bolt threads, nut threads, nut bearing surfaces, washers, and nut bearing surfaces on flanges; high-temperature anti-seizure agent shall be applied as required.
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