| abstract |
Compositions for simultaeously removing iron and copper scales from ferrous metal surfaces comprise water, one or more organic chelating acids which dissolve iron, one or more reducing agents selected from erythorbic acid, alkali metal salts of erythorbic acid, and ammonium salts of erythorbic acid, and, as copper complexing compound, thiourea and/or hexahydropyrimidine-2-thione. The compositions are utilized by contacting scale-containing ferrous metal surfaces therewith at temperatures of from about 75°F (24°C) to about 150°F (66°C). |