Pipe flanges, equipment flange gaskets
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For pressure vessels, under what circumstances should fastener washers be used? HG20592 recommends washers with a hardness of 300HV or 200HV
The standards are contradictory: in the main section on fasteners, only bolts, studs, and nuts are mentioned, yet washers are listed later on. Washers are not specified in the standards for manholes and handholes.
Container flanges are not provided either; could this be considered for applications with low pressure?
Generally, consideration should be given to vibration and temperature fluctuations, and washers need to be added for studs of M30 and above. However, in the above situations, we did not use washers, and no leaks occurred.
The fasteners used for the flanges and manholes of pressure vessels are sturdy, with no vibration, making it difficult for them to loosen. After using shims, under high-load conditions the shims may deform, thereby causing leaks. Insulating gaskets and insulating sleeves are used in some special occasions.
As for the washer, in my opinion, it serves to protect the flange surface from wear during the installation or removal of nuts; it is a component that is prone to damage while the equipment is in operation. Or the gap between the bolt hole and the bolt is too large; washers can be used to increase the compressed surface area, etc
Gaskets are generally not seen on pressure vessels