Steel industry acid corrosion

The EPA defines corrosivity in terms of pH (i.e., wastes with pH <2 or >2.5) or in terms of ability to corrode steel (SAE 20) at a rate of >6.35 mm (0.250 in.) per year at a temperature of 55 C (13°F). This discussion will address corrosivity as it applies to acids and caustics. Acids are compounds that yield H ions (actually HjO ions) when dissolved in water. Common industrial acids include acetic, nitric, hydrochloric, and sulfuric acids. The terms concentrated and dilute refer to the concentrations in solution. Mixing a concentrated acid with enough water will produce a dilute acid. For example, a bottle of concentrated HCl direct from the manufacturer is approximately 12 N in HCl, while a solution of HCl used in a titration may be only 0.5 N. The latter is a dilute acid solution. 

Nitric acid is used by the steel industry to remove surface oxides (pickling) of stainless steels, to brighten and clean surfaces after salt-bath descaling and to prepare stainless steel surfaces for corrosion resistance (passivation). 

Very often the long experience with chemicals operating as corrosion inhibitors, e. g. in the oil field, gas or petroleum industry, is taken as an example for the successful use of corrosion inhibitors for many decades. This undoubtedly is true and the overwhelming majority of literature on corrosion inhibitors deals with the effects of inhibitors on uniform corrosion, e. g. of steel in acidic or neutral solutions, where they can be classified into [2] a) adsorption inhibitors, acting specifically on the anodic or on the cathodic partial reaction of the corrosion process or on both reactions (mixed inhibitor), b) JUm-forming inhibitors, blocking the surface more or less completely, and c) passivators, favouring the passivation reaction of the steel (e. g. hydroxyl ions). 

Zinc-nickel Zn-Ni alloys with 5 to 15 wt% Ni offer excellent corrosion resistance and are mainly used in the automotive, aerospace, and electronics industries. Above 15% Ni, the alloy coating becomes more noble than steel, and the corrosion-protection mechanism changes from a sacrificial to a pure physical one (comparable to pure Ni coatings, see Sect. 5.5.4.2.2). They can be electrode-posited from acid or alkaline baths. The acid baths are usually based on sulfate, chloride, sulfate-chloride, pyrophosphate, or acetate (Table 15). The system shows anomalous codeposition (see Sect. 5.5.1.2), which has been explained by a hydroxide suppression mechanism [47]. As in the case of Ni-Fe, the alkaline baths must contain complexing agents (see Sect. 5.5.4.6.2). The alloys electroplated from add haths contain approximately 10 to 14% Ni, whereas the alkaline Zn-Ni... 

The stainless steels have excellent corrosion resistance in outdoor environments. They will suffer some rust staining when exposed to chlorides (seacoast, deicing salts) and/or acid industrial fumes. The higher the alloy content of the stainless steel, particularly chromium, molybdenum, and nitrogen, the better the performance. 

The first attempts to use anodic protection (AP) were made by Edeleanu (1954), who protected stainless steel tanks against corrosion by sulfuric acid. The first reports on the application of AP in the chemical industry in the U.S.A. were given by several research teams Sudbury et al. (1960), Riggs et al. (1960), and Locke et al. (1960). Riggs and Locke (1981) summarized achievements in AP up to 1979. 

Hass H, Herfiirth E, Stoffler G, Redl B (1992) Purification, characterization and partial amino acid sequences of a xylanase produced by Penicillium chrysogenum. Biochim Biophys Acta 1117 279-286 Heisey RM, Papadatos S (1995) Isolation of microorganisms able to metabolize purified natural rubber. Appl Environ Microbiol 61 3092-3097 Hernandez G, Kucera V, Thierry D, Pedersen A, Hermansson M (1994) Corrosion inhibition of steel by bacteria. Corrosion 50 603-608 HespeU RB, O Bryan-Shah PJ (1988) Esterase activities in Butyrivihrio fibrisolvens strains. Appl Environ Microbiol 54 1917-1922 HiU EC (1987) Microbial problems in the off-shore oil industry. Institute of Petroleum, London, pp 25-28... 

Some industrial wastes, for example pickling liquor used to remove corrosion from steel, contain acidic metal ions and often some excess strong acid. For such wastes, the determination of acidity is important in calculating the amount of lime, or other chemicals, that must be added to neutralize the acid. 

A patent application on the use of a corrosion inhibitor in well stimulation application was not filed. Apparently, this was because corrosion inhibition was thought to be an old art adapted from the steel industry, dating as far back as 1845. In any case, the treatments were successful. However, acidizing declined in use in the early 1930s with a drop in oil prices. ... 

Ashassi-Sorkhabi, H. Es haghi, M. (2009). Corrosion inhibition of mild steel in acidic media by [BMIm]Br Ionic liquid. Mater. Chem. Phys., 114, 267-271, ISSN 0254-0584. Atkins, M. P. Bowlas, C. Ellis, B. Hubert, F. Rubatto, A. Wasserscheid, P. (2002). In Rogers, R. D. Seddon, K. R. Volkov, S. Editors, Green Industrial Applications of Ionic Liquids, Kluwer Academic Publishers, ISBN 1402011377, Dordrecht, 49-66. 

Chemical-Process Vessels. Explosion-bonded products are used in the manufacture of process equipment for the chemical, petrochemical, and petroleum industries where the corrosion resistance of an expensive metal is combined with the strength and economy of another metal. AppHcations include explosion cladding of titanium tubesheet to Monel, hot fabrication of an explosion clad to form an elbow for pipes in nuclear power plants, and explosion cladding titanium and steel for use in a vessel intended for terephthaHc acid manufacture. 

Acid Coolers. Cast Hon trombone coolers, once the industry standard (101), are considered obsolete. In 1970, anodically passivated stainless steel sheU and tube acid coolers became commercially available. Because these proved to have significant maintenance savings and other advantages, this type of cooler became widely used. Anodic passivation uses an impressed voltage from an external electrical power source to reduce metal corrosion. 

Arsonic and arsinic acids have found a number of industrial uses. They have been used as corrosion inhibitors for iron and steel, additives to motor fuel, agricultural bactericides, herbicides, and fungicides. 3-Nitro-4-hydroxyphenylarsonic acid (roxarsone) [121 -19-7] C H AsNOg, has found widespread use as an additive to poultry feed for the control of coccidiosis and other poultry diseases (122,123). Arsanilic acid [98-50-0] C HgAsNO, has also been used for this purpose (124) and for growth promotion in swine. It is manufactured and suppHed by Duphar Nutrition Co., Inc., Fleming Laboratories, Inc., Dr. Mayfield Laboratories, Inc., and Whitmoyer Laboratories, Inc. 4-Nitrophenylarsonic acid [98-72-6] C H AsNO and... 

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