Corrosion Tests in the Processing Of Soap and Fatty Acids

A summary of the results of corrosion tests made in operating equipment in soap and fatty acid plants during the past 10 years, using mostly the spool-type testing device. Tests in the boiled soap process and glycerine recovery include those in soap kettles, caustic storage, brine tanks, acid and alkali treatment and filtering of soap lye, salt-glycerine slurry, salt-glycerine evaporators and glycerine stills, glycerine bleaching and storage. Tests in fatty acid processing include those in Twitchell and high temperature water splitting of fats, acid washing of fats and fatty acids, deodorization, heating and distillation of animal and vegetable fatty acids including tall oil, fatty acid storage. All tests did not include all of the same metals and alloys but the program included a wide variety of materials such as nickel, Monel, Inconel and other high nickel alloys, stainless steels, copper and copper alloys, aluminum, chemical lead, mild steel, alloy steels and plain and alloy cast irons. Test results are evaluated where possible.