Can a necked flange be connected to a plate flat welding flange?
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Dear experts, I have a question from a beginner: can a necked flange be connected to a plate flat welding flange? Thank you!
If the sealing surfaces, gaskets, as well as the diameter and number of bolts are identical, connection is possible; however, several factors need to be taken into account: 1, only non-metallic gaskets can be used, 2, care must be taken in controlling the preload. Due to the significant difference in their ability to resist flange bending moments, necked flanges and plate-type butt weld flanges are generally not used together.
No mandatory regulations were found in the standards; however, even if the dimensions and connections are acceptable, it is only permissible to use a higher grade material in place of a lower one, with the allowable parameters to be determined according to SO.
It can be used, provided that the pressure rating meets the requirements, the type of sealing surface is compatible, and the nominal diameter is the same.
Why does it have to be connected in this way? It’s better not to use it at all
If the bolt holes can align more or less, it can be used, but it’s not designed for such use
Why can only non-metallic gaskets be used? Is it because the pressure rating is not high?
Flanges with neck welding and plate types suitable for flat welding can still be connected; there is no problem at pressures up to 16 kilograms
When the form and size of the sealing surfaces are the same, as well as the dimensions of the flange connection (the position, size, and number of bolt holes), it should be possible to make the connection; I agree with what was said by the person in floor 2, and attention should also be paid to the preload. But I don’t quite understand what he meant by saying that only non-metallic gaskets can be used; I hope to get an answer.
This is related to the sealing specific pressure of the gasket. The winding gasket Y is relatively large, resulting in poor bending resistance of the plate flange; it may deform during pre-tightening of the gasket, failing to ensure a proper seal.