ANTICORROSION TREATING METHOD OF OUTER SURFACE OF HEAT EXCHANGE PIPE MADE OF ALUMINUM EXTRUSION MATERIAL AND MANUFACTURING METHOD OF HEAT EXCHANGER

摘要

PROBLEM TO BE SOLVED: To provide an anticorrosion treating method of an outer surface of a heat exchange pipe made of aluminum extrusion material capable of improving pitting corrosion resistance.SOLUTION: An anticorrosion treating method is applied to an outer surface of a heat exchange pipe 4 made of aluminum extrusion material which is formed with an alloy containing 0.2 to 0.3 mass% of Mn, 0.05 mass% or less of Cu and 0.2 mass% or less of Fe and has a thickness of pipe wall of 200 μm or less. In the anticorrosion treating method, dispersion liquid prepared by dispersing and mixing flux powder and Zn powder having an average particle size 3 to 5 μm and a maximum particle size less than 10 μm into binder is applied, a liquid component in the dispersion liquid is vaporized, and Zn powder and flux powder are deposited to the outer surface of the heat exchange pipe 4 such that Zn powder deposition amount gets to 1 to 3 g/m, flux powder deposition amount gets to 15 g/mor less and the ratio of flux powder deposition amount to Zn powder deposition amount (flux powder deposition amount/Zn powder deposition amount) gets to 1 or more.