METHOD FOR REMOVING SILICA-BASE SCALE

• Main Authors: ITO KENICHI, TOGO NAOKO
• Format: Patent
• Language: English
• Published: 13.02.2003
• Edition: 7
• Subjects: BLASTING; CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE ORHEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS; CLEANING OR DEGREASING OF METALLIC MATERIAL BY CHEMICALMETHODS OTHER THAN ELECTROLYSIS; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; HEAT EXCHANGE IN GENERAL; HEATING; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; LIGHTING; MECHANICAL ENGINEERING; METALLURGY; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; WEAPONS

PROBLEM TO BE SOLVED: To provide a chemical cleaning method for effectively removing silica- base scale including silica and/or silicate adhering to the metal surface, out of the removal method, without damaging a passivation coating, while inhibiting corrosion of the metal to the minimum. SOLUTION: The method for removing the silica-base scale adhering to the metal surface is characterized by (1) cleaning the silica-base scale including silica and/or silicate adhering to the metal surface with a cleaning liquid containing fluoride, and subsequently (2) passivating the metal surface with a passivation liquid containing fluoride and peroxide.