Coating of Flange Faces
Coating of Flange Faces
(OP)
I have an air receiver (DP = 1034 kpa) for which the bottom head and 1/3 of shell requires internal epoxy coating. Per the client specification, the nozzle neck, flange and first third of the flange face also require coating. The flange face coating detail indicates that a reduced coating thickness of 75 micro meters shall be used to coat the first 1/3 of the flange face. The concern arose regarding gasket sealing.
1) Is it common to coat flange faces if the vessel is internally coated?
2) Will the gasket seal properly?
I would appreciate hearing anyones experience.
Thanks.
1) Is it common to coat flange faces if the vessel is internally coated?
2) Will the gasket seal properly?
I would appreciate hearing anyones experience.
Thanks.





RE: Coating of Flange Faces
Now, if you provide epoxy coating on the nozzle neck and bottom portion of the flange and not cross over into the raised face portion of the flange, you will have satisfied the owners requirement and not compromised the sealing capabilities of the flange itself.
Make sense?
RE: Coating of Flange Faces
The only time I have seen this area covered (other than by a gasket) is when the vessel is rubber or plastic lined. This type of lining normally covers the fulll flange face - including the gasket seating area.
RE: Coating of Flange Faces
So, if you coat, coat the whole flange face. If you don't... then it is a moot point.
Frankly, I wouldn't coat. The clamping force can't be too kind to the coating possibly damaging it and causing it to fail. But I would coat the metal surface right up to the edge of the flange face where the gasket would be.
rmw
RE: Coating of Flange Faces
Choose another gasket type- nobody says that you have to use a spiral-wound gasket for 10 bar air. Use a gasket material with some elastomer content, so it'll be more compliant to the inevitable irregularities in the coated surface.
This is the client's call since they're the ones who are asking for the 1st third of the flange face to be covered. But I'd coat the entire flange face with the same thickness as the rest of the vessel was coated with. If you have to blast before applying the epoxy, unless you do a very good job of masking, you're going to end up damaging the rest of the flange face anyway.
RE: Coating of Flange Faces
RE: Coating of Flange Faces
I think with a flat gasket that the 75 microns would create a problem if only one third of the face was covered. If they whole face was covered then it would be ok provided the gasket material was suitable sealing on a painted surface.
However generally I would always avoid coating a raised face, only times I would do it is for rubber lining but then that would be a flat faced flange instead. Paint the neck and leave the flange face unpainted and allow for a suitable corrosion allowance in your design.
RE: Coating of Flange Faces
It makes sense, right on the spot.
Cheers,
gr2vessels