Discussion on the corrosion mechanism of this pipe fitting?
Thread Content
The picture above shows the problem that occurred at the bottom of the large and small heads of the medium-pressure superheated steam pipeline during maintenance. The initial judgment should be corrosion, but what is the mechanism? Please participate in the discussion and win prizes!
It should be chloride corrosion. Chloride corrosion of carbon steel is uniform and continuous, accompanied by hydrogen embrittlement.
Sir, please provide the working parameters, working medium and material of the equipment to facilitate discussion.
The working temperature of Siyi small and large head pipe fittings in the picture: Around 300 degrees ； Pressure 4.0MPa ； The medium is medium pressure superheated steam.
Judging from the picture, it is likely that the corrosive medium dissolved into the steam condensate and caused corrosion to the carbon steel pipe.
Judging from the corrosion products, the possibility of sulfurization is the greatest, and the conveying medium contains sulfur!
The medium may contain sulfur and H2S. Under high temperature conditions, the reaction between sulfur and hydrogen sulfide promotes the hydrogen evolution reaction, leading to hydrogen-induced cracking.
It seems that the medium of the upstream sulfur-containing equipment is leaking, generating S compounds, and when the superheated steam passes through the large and small openings, condensation droplets are generated and attached. . . . . . . .