Metal Dusting Corrosion of 9Cr-1Mo Steel in Propane-Butane Gas Mixture
The kinetics and mechanism of metal dusting corrosion of 9Cr-1Mo steel, commonly used in CCR platforming units, have been studied as a function of temperature (773 – 1173 K) in propane-butane atmosphere, being the mixture of 70 vol. % of propane and 30 vol. % of butane with the total pressure equal 105 Pa. The kinetics of corrosion have been studied thermogravimetrically in the apparatus enabling the mass changes of corroded sample to be followed continuously with the accuracy of the order of 10-6 g. It has been found that metal dusting corrosion in this atmosphere, modeling in some way industrial environments in petrochemical industry, is complex and two-stages of linear kinetics may be distinguished. In the first stage, which may be considered as an incubation period, the reaction proceeds with rather low rate, which increases dramatically in the second stage, the beginning of which depends strongly on temperature. Linear course of reaction indicates that chemical reactions and not diffusion processes determine the rate of corrosion. This conclusion is confirmed by the fact, that the layer of corrosion products is not compact but considerably porous.
A. Agüero, J.M. Albella, M.P. Hierro, J. Phillibert and F.J. Pérez Trujillo
Z. Grzesik et al., "Metal Dusting Corrosion of 9Cr-1Mo Steel in Propane-Butane Gas Mixture", Defect and Diffusion Forum, Vols. 289-292, pp. 477-483, 2009