Patent ID: 6348440
Filing Date: 2002-02-19
Classification: C11D,C23G

Abstract:
The method for cleaning iron oxide containing scale from a surface of at least one of high strength steels, steels used for pressure vessel plating, welded metals, steels galvanically coupled to stainless steels, and steels containing heat affected zones (HAZ) resulting from a welding process, comprising contacting the surface with a composition comprising 1-hydroxy-ethylidene-1,1-diphosphonic acid and at least one of ethoxylated mercaptan and oxidized ethoxylated mercaptan, and at least one of benzotriazole and benzimidazole compound having the following structure: wherein X is C or N, each of R1, R2, R3 and R4 is hydrogen, halogen, or a hydrocarbyl group.