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E: ssas@bssa.org.uk
Some chemical have both a ‘scientific’ and ‘common’ name, for example caustic soda is the common name for sodium hydroxide. Most corrosion table data uses the scientific names and so finding information can sometimes be difficult when only a common name is known. Reference is also made to alum, aqua fortis, aqua regia, bleach, caustic potash, chromic acid, ethanol and methanol (alcohol), glycol, gypsum, javelle (javel) water, Labarraque’s solution, marine acid, muriatic acid, oil of vitriol, oleum, rock salt, salt acid, spirit of salt, sulphurated hydrogen and wood acid.
The carbon ranges of ‘normal’ and ‘low’ carbon 304 (304L) and 316 (316L) types are compared. The effect of carbon on intercystalline corrosion resistance and welding is also covered and why steel is often offered as a dual certified product. European grades 1.4301 1.4306 1.4307 1.4401 and 1.4404 are included in the comparisons.
This article provides a link to the Outokumpu web-site.This provides a web based version of the tables published as the ‘Outokumpu Stainless Corrosion Handbook’. The chemical compatibility of a range of stainless steel types with a large range of acids, bases, compounds, some foodstuffs and liquid metals can be assessed using these tables. Tables include acetic acid, acetone, aluminium chloride and sulphate, ammonium bisulphite, bromide, carbonate, fluoride and chloride, benzene, beryllium chloride, boron trichloride, bromine, calcium chloride, carbon tetrachloride, chloric acid, chlorine, chlorine dioxide, chlorobenzene, chloroform, chromic acid (chromium trioxide), cobalt sulphate, copper acetate and cyanide, ether, ethyl alcohol, ethylene bromide, fluorine, formaldehyde, formic acid, glucose, glycerine, glycol, hydrobromic acid, hydrogen chloride gas, hydrogen iodide and peroxide, hydrogen peroxide, iodine, iron (ferrous and ferric) chloride, iron nitrate, lactic acid, lead nitrate, lithium chloride, magnesium sulphate, malic acid, mercury, methyl alcohol, methylene chloride, nickel chloride, nitrous acid, oxalic acid, perchloric acid, phenol, potassium bisulphate, chlorate and dichromate, silver bromide, sodium bicarbonate, chlorate, citrate, hydroxide, hypochlorite, perborate, perchlorate, phosphate, silicate, thiosulphate, stannic (tin) chloride, sulphamic acid, sulphur, sulphurous acid, sugar, tannic acid (tannin), tartaric acid, textile dyes, toluene, trichloroethylene, urea, urine, vinegar, xylene, zinc and zirconium oxychloride. This data was originally compiled jointly in Sweden by technical specialists at Avesta and Sandvik.
The main factor in the selection process for stainless steels is corrosion resistance. Careful consideration of the application should be done to enable a choice of grade with suitable corrosion resistance whilst keeping costs to an economic minimum. Other considerations such as mechanical properties (strength and toughness), physical properties (magnetic permeability) and forming, fabrication and joining methods available should be secondary. (91)
Appropriate grade selection is a balance between attaining adequate corrosion resistance, whilst minimising cost. Useful aids to material selection include the Outokumpu Stainless Corrosion Handbook and the Nickel Institute’s Crevice Corrosion Engineering Guide.