METHOD FOR CORROSION INHIBITION OF METAL IN OPEN TYPE CIRCULATING COOLING WATER SYSTEM

• Main Authors: ITO KENICHI, TOGO NAOKO
• Format: Patent
• Language: English
• Published: 30.07.2003
• Edition: 7
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; COMPOSITIONS BASED THEREON; DIFFUSION TREATMENT OF METALLIC MATERIAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLICMATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASSC23 AND AT LEAST ONEPROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25; NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

PROBLEM TO BE SOLVED: To provide an excellent method for corrosion inhibition of metal in an open type circulating cooling water system of a high silica concentration without containing environmental pollutants, such as heavy metals and phospho rus, and without forming scale in the water system by increasing the thickening degree of a cooling water column. SOLUTION: The method of suppressing the corrosion of the metal in the open type circulating cooling water system comprises increasing the thickening degree of the cooling water column and adding a water-soluble maleic acid copolymer composed as (A) 70 to 90 wt.% (in terms of maleic anhydride) ≥1 kind of maleic anhydride, maleic acid and their water-soluble salts and (B) 10 to 30 wt.% nonionic monoethylenically unsaturated monomer into circulating water prepared in such a manner that the silica concentration is 70 to 300 (mg/l) and that a correction Ryznar index; RI' including a correction term of a silica concentration expressed by formula: RI'=RI-0.004×[SiO2] (mg/l) (where RI is a Ryznar index at 40°C and [SiO2] (mg/l) is the silica concentration in the circulating water) attains 3.0 to 6.0. COPYRIGHT: (C)2003,JPO