Metals industry acid corrosion

Chlorosulfuric acid attacks brass, bronze, lead, and most other nonferrous metals. From a corrosion standpoint, carbon steel and cast Hon are acceptable below 35°C provided color and Hon content is not a concern. Stainless steels (300-series) and certain aluminum alloys are acceptable materials of constmction, as is HasteUoy. Glass, glass-lined steel, or Teflon-lined piping and equipment are the preferred materials at elevated temperatures and/or high velocities or where trace Hon contamination is a problem, such as in the synthetic detergent industry. 

In contrast to the situation of a decade ago [3.1). a substantial literature has now accumulated on copper removal by activated carbons. This is not only because of metal recovery from acid mine wastes [176] and acidic corrosion of pipes [33] but also because of increasing industrial contamination of water streams [177-182]. In particular.many wastewaters contain complexing ions such as ethylenedi-aminetetraacetate (EDTA) and the removal of EDTA-chelated copper (and other) ions has been a special focus of attention [45,173,183-186]. 

Most chromium is used in three basic industries chemical, metallurgical and refractory (heat-resistant) (Barceloux 1999), with the metal industry using the majority. Ferrochrome, an iron/chromium alloy, is used as an additive to produce chromium-steels which are stainless and hard. Chromic acid solutions are employed in electroplating of chromium on other metals to imPart corrosion resistance and for decorative purposes. The refractory industry has... 

Dequest . [Monsanto] Hiosphoiic acids and salts process aid for papa, textiles, metals, industrial cleaners scale and corrosion inhibitor. 

A. Kotone, T. Hori, M. Hoda, and Y. Nakane. Corrosion inhibition of metals in acidic solutions. IP Patent 48 089 141, assigned to Sakai Chemical Industry Co., Ltd., November 21, 1973. 

Synonyms Hexamethylenediaminetetra (methylene phosphonic acid) HMDTMP Empiricai C10H28N2O12P4 Properties Wh. powd. m.w. 492.23 Uses Scale/corrosion inhibitor for industrial water systems aq. process additive for paper, textiles, and metals industrial and commercial formulations for cleaning various substrates chelating agent... 

CAS 38820-59-6 EINECS/ELINCS 254-135-7 Synonyms Hexamethylene diamine tetramethylene phosphonic acid, potassium salt (1,6-Hexanediylbis (nitrilobis (methylene))) tetrakisphosphonic acid potassium salt Hexapotassium hexamethylene diamine tetra (methylene phosphonate) HMDTMP KgHDTMP Phosphonic acid, [1,6-hexanediylbis [nitrilobis (methylene)]] tetrakis potassium salt Classification Phosphonate Empirical C10H28N2O12P4 xK Properties M.w. 765.98 Toxicology LDLo (oral, rat) 10 g/kg LD50 (dermal, rabbit) > 7940 mg/kg TSCA listed Uses Process additive for paper, textiles, and metals industrial and commercial formulations for cleaning various substrates scale and corrosion inhibitor in aq. systems deflocculant, sequestrant, scale/corrosion inhibitor, metal ion control in water treatment, boiler treatments, reverse osmosis. 

A hydroxide or carbonate of an alkali metal (e.g., lithium, sodium, potassium, etc), the aqueous solution of which is characteristically basic in chemical reactions. The term may be extended to apply to hydroxides and carbonates of barium, calcium, magnesium, and the ammonium ion. The term alkali should be viewed in relation to the terms corrosive, bases and acids. 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 (i.e., alkali materials). 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 12N in HCl, while a solution of HCl used in a titration may be only 0.5N. The latter is a dilute acid solution. 

In practice, inhibitors are often defined according to their field of application. In aqueous environments, inhibitors for acid environments are typically used to minimize metal corrosion during pickling of steel, an operation that removes oxide scales by dissolution in an acid. In the petroleum industry, large quantities of inhibitors for acid environments are used to avoid corrosion of drilling equipment. Inhibitors for neutral environments are used above all for the protection of cooling-water circuits. Inhibitors not only reduce the rate of uniform corrosion, but they also serve to protect metals from localized corrosion and stress corrosion cracking [18]. 

Anodic protection s is a modern electrochemical technique for protecting metallic equipment used in the chemical-process industry against corrosion and handling highly corrosive chemicals (e.g., concentrated sulfuric and orthophosphoric acids). The technique consists in impressing a very low anodic current (i.e., usually 10 irA.m" ) on a piece of metallic equipment (e.g., tanks, thermowells, columns) to protect against corrosion. This anodic polarization puts the electrochemical potential of the metal in the passivity region of its Pourbaix... 

Uses Metalworking surfactant corrosion inhibitor for oil and gas industry, acid cleaners inhibitor against acid on zinc coated and ferrous metal surfs. protects against phosphoric, hydrochloric, and sulfuric acid attack Properties Brownish reddish vise, liq. sol. in water dens. 1.11 g/cc pH 3.5-5.5... 

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