Models for the anaerobic phases of marine immersion corrosion

In the phenomenological model for the general marine corrosion of mild (and high strength low alloy) steel introduced previously, the corrosion process eventually enters a state governed predominantly by the activity of sulphate-reducing bacteria (SRB). This state has been modelled by two consecutive phases, the first describing a transient behaviour and the second the longer-term quasi-steady-state corrosion response. In earlier papers these have been described only by bounding parameters, calibrated to comprehensive field data. Herein a plausible idealized mathematical model is proposed for the corrosion losses within these phases. The model is based on an idealization of the distribution of nutrients within the corrosion product layer and its depletion by SRB as the anaerobic conditions necessary for their metabolism develop. With the gradual depletion of nutrients, the activity of the SRB reduces to a quasi-steady-state process governed by the rate of external nutrient supply and the loss of (protective) corrosion product. It follows that high levels of nutrients, such as in offshore oilfields and in nutrient-polluted waters can be associated with high rates of corrosion under anaerobic conditions. Also, in warmer (tropical) waters, the metabolism of SRB is enhanced. Both phenomena are consistent with field observations. A preliminary calibration of the models for phases 3 and 4 is attempted using the limited available field data.

[1]  Robert E. Melchers,et al.  Influence of Water Velocity on Marine Immersion Corrosion of Mild Steel , 2004 .

[2]  J. R. Lewis,et al.  Corrosion and Marine Growth on Offshore Structures , 1984 .

[3]  M. Romero,et al.  A Study of Microbiologically Induced Corrosion by Sulfate-Reducing Bacteria on Carbon Steel Using Hydrogen Permeation , 2005 .

[4]  C. P. Larrabee,et al.  Corrosion of Steels in Marine Atmospheres and in Sea Water , 1945 .

[5]  Robert E. Melchers,et al.  Modelling of marine immersion corrosion for copper-bearing steels , 2003 .

[6]  R. Bartha,et al.  The Sulphate-Reducing Bacteria , 1979 .

[7]  Richard I. Ray,et al.  Relationship Between Corrosion and the Biological Sulfur Cycle: A Review , 2000 .

[8]  Robert E. Melchers,et al.  Effect of Nutrient-Based Water Pollution on the Corrosion of Mild Steel in Marine Immersion Conditions , 2005 .

[9]  Robert E. Melchers,et al.  Effect on marine immersion corrosion of carbon content of low alloy steels , 2003 .

[10]  J. D. Bultman,et al.  CORROSION OF METALS IN TROPICAL ENVIRONMENTS. FINAL REPORT OF 16-YEAR EXPOSURES , 1976 .

[11]  G. M. Ferrari,et al.  Development of high strength low alloy steels for marine applications: Part 1: Results of long term exposure tests on commercially available and experimental steels , 1986 .

[12]  R. Melchers.  Modeling of Marine Immersion Corrosion for Mild and Low-Alloy Steels—Part 1: Phenomenological Model , 2003 .

[13]  T. Hansen.  Carbon Metabolism of Sulfate-Reducing Bacteria , 1993 .

[14]  C. P. Larrabee,et al.  Corrosion Resistance of High-Strength Low-Alloy Steels As Influenced by Composition and Environment , 1953 .

[15]  Robert E. Melchers,et al.  Effect of small compositional changes on marine immersion corrosion of low alloy steels , 2004 .

[16]  Robert E. Melchers,et al.  Mathematical modelling of the diffusion controlled phase in marine immersion corrosion of mild steel , 2003 .

[17]  J. Odom,et al.  The Sulfate-Reducing Bacteria: Contemporary Perspectives , 1993, Brock/Springer Series in Contemporary Bioscience.

[18]  John Crank,et al.  The Mathematics Of Diffusion , 1956 .

[19]  J. D. Bultman,et al.  INFLUENCE OF MARINE ORGANISMS ON THE LIFE OF STRUCTURAL STEELS IN SEAWATER , 1974 .

[20]  David W. Smith.  Ecological Actions of Sulfate-Reducing Bacteria , 1993 .

[21]  Christofer Leygraf.  Atmospheric corrosion , 2000 .

[22]  P. Dillmann,et al.  Advances in understanding atmospheric corrosion of iron. II. Mechanistic modelling of wet–dry cycles , 2004 .

[23]  C R Southwell,et al.  CORROSION OF METALS IN TROPICAL WATERS, STRUCTURAL FERROUS METALS , 1970 .

[24]  Bopinder S. Phull,et al.  Seawater Corrosivity Around The World: Results From Five Years of Testing , 1997 .

[25]  J. Crolet,et al.  From biology and corrosion to biocorrosion , 1992 .

[26]  A. K. Tiller,et al.  Microbial corrosion-1 , 1988 .

[27]  Robert E. Melchers,et al.  Effect of Immersion Depth on Marine Corrosion of Mild Steel , 2005 .