Abstract:

On the base of the corrosive theory and the effected factors, this paper presented the phenomena shown in the article” The Failure Analyses of the Boiler Tube of vapor Generator”. The decreasing wall thickness of boiler tube of vapor generator mainly resulted in the inner wall corrosion of the tube, and then the radius cross section of the boiler tube produced fracture and sub-fracture, and the corrosive surface of the tube produced some erosion and cavitation. The paper introduced the principle of the decreasing wall thickness of boiler tube of vapor generator. Under the high temperature and high pressure, the metal in contact with the vapor-water formed the vapor-water corrosion, the tube wall is corroded and mainly produced iron oxide. The liquid heated in the tube produces a lot of bubbles when flowing, the oxidic film and metal base will be damaged when the bubbles break, .At the same time, stress and active anion will destroy the oxidic film. Corrosion is more serious duo to the solid particles and oxygen in the liquid. By the discussion in this paper, the corrosion and the decreasing wall thickness of boiler tube are understood clearly, and it provides a guide for the vapor generator application.

Key words: principle, vapor- water corrosion, couple corrosion, erosion, cavitation