Common sense of anticorrosion of mechanical seals for kettles

The anti-corrosion work of mechanical seals for kettles is very important. Today, I will share with you some common knowledge of anti-corrosion of non-metallic rings:

1. Corrosion of graphite ring. The impermeable graphite ring impregnated with resin has three reasons for its corrosion: one is that when the end face is overheated and the temperature is greater than 180oC, the impregnated resin must be broken away from the graphite ring to reduce the wear resistance of the ring; Inappropriate, so the establishment of the sealed cooling system, which is mainly caused by the wrong selection of materials. For film-forming corrosion, the passivation film usually has the characteristics of maintenance effect, but the materials used for metal sealing rings, such as stainless steel, cobalt, chromium alloy, etc., are damaged in the end face friction The film is difficult to form. It is very necessary to choose a corrosion-resistant impregnating resin, use high-pressure impregnation, and increase the impregnation depth.

2. Oxidation of graphite rings. In an oxidizing medium, when the end face is dry rubbed or poorly cooled, the temperature of 350-40°C can cause the graphite ring to react with oxygen, generate CO, gas, and make the end face rough and even cracked. Non-metallic rings will also break under the combined effect of chemical media and stress.

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3. Corrosion of PTFE (tetrafluoroethylene gasket) sealing ring. The chemical change will occur in the medium, and the wear resistance will also be reduced; the third is that the resin impregnation depth is not good, and the wear resistance will be reduced when the impregnated layer is removed. Filled with F4 such as glass fiber, cracks first occur in the thin area, and then develop to the depth to break. The cracks of the sealing ring are usually radially divergent, and there may be one or more cracks. Graphite powder, metal powder, etc. to improve its temperature resistance and wear resistance. The corrosion of the filled F4 ring mainly refers to the selective corrosion, dissolution or deterioration of the filling. For example, in hydrofluoric acid, the glass fiber molecules are thermally corroded, so what is filled should be determined according to the specific situation.