METHOD OF CLEANING METAL SURFACES FROM DEPOSITS Russian patent published in 2002 - IPC

FIELD: cleaning metal surfaces of boilers, coolers, electric filters and other items of equipment from deposit containing carbonates, sulfates and silicates of alkali-earth metals, lead and iron, as well as silica and other admixtures; cleaning walls of heat exchangers, condensers, boilers and other items of equipment from deposit. SUBSTANCE: method includes two-stage treatment of surfaces: with aqueous alkali solution at first stage and with aqueous solution at second stage: used as aqueous alkali solution is solution containing the following components, mas.%: caustic soda, 35-43; sodium polyphosphate, 3-4; water, the balance. Aqueous solution used at second stage contains, mas. %: aminoester of orthophosphrotic acid, 0.08-0.15; polydimethyl diallyl ammonium fluoride, 0.3-0.7; water, the balance. EFFECT: enhanced efficiency. 1 tbl, 1 ex