What are the high requirements of pressure vessels for flanges?

As a pressure vessel, it must have the following characteristics, such as high-temperature resistance, corrosion resistance, leakage prevention, and easy repair.

However, the flange interface of a pressure vessel is usually the only channel for handling materials and the interface for docking other facilities.
The tightness of the butt joint seal of the pressure vessel must be guaranteed for a long time for each pressure vessel and the precision of the sealing groove of the flange end face and the quality of the material have a more direct impact on the sealability.

First of all, under the premise of ensuring the accuracy of the sealing groove of the flange end face and the quality and performance of the material, the sealing strip in the sealing groove must also have sufficient extrusion force to achieve the sealing effect.
When the aperture of the flange is large and the medium in the container is high temperature, high pressure, and strong corrosion, the sealing groove of the end face of the container flange very easy to generates cracks.
In order to suppress the crack expansion, regular maintenance of the pressure vessel, screening out the metal layer with cracks in the sealing groove of the flange end face, and repairing them can effectively prevent leakage, explosion and other accidents.

If cracks occur in the sealing groove of the flange end face of the pressure vessel, there are two repair situations according to the size of the cracks: one is that only the surface layer has cracks, which have little effect on the transition layer.

The repairing process is: eradicate the surface layer with cracks→resurfacing the corrosion-resistant surface metal→flaw detection→machining the sealing surface;

The other is that the crack has grown to the transition layer metal, even to the base metal,

The repair process is: eradicate all metal layers with cracks→surfacing transition layer metal→heat treatment→flaw detection→surfacing corrosion-resistant surface metal→flaw detection→machining the sealing surface.

In addition, the repair process is also very important in the use and maintenance of flanges, because some small cracks can be improved through correct repair methods, and there is no need for major repairs.

Neck flange connection or flange joint refers back to the detachable connection of the flange, Gasket and bolt as a group of combined sealing structures.