Abstract
Hot water supply aluminized steel pipe (125 A) corroded and leaked in about six years. The average corrosion rate is estimated to be 0.76 mm/year for the use period. It is very large as the corrosion rate of the carbon steel pipe. The corroded pipe was analyzed. The corrosion examination on the defective aluminized steel test piece with the hot water test tank at 60℃and the corrosion test on the defective aluminized steel test piece in hot water supply piping system were done. The base steel of aluminized steel test piece corroded in each aluminum plating defect part. Moreover, corrosion potentials of the aluminized steel (surface pure Al layer, Fe-Al alloy layer and base steel) were measured. The corrosion potentials of surface pure Al layer and Fe-Al alloy layer are more noble than base steel at 60℃ and room temperature. As a result, it is thought that this corrosion depends on the localized corrosion generated by the reverse electrical potential between Al (particularly Fe-Al alloy) and base steel.
