鋳鉄製ポンプ部品に生ずる黒鉛化腐食の超音波診断

概要

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Cast iron parts of water supply and drainage pumps are usually used under corrosive environments and graphitic corrosion develops in the areas near water-air interface. In this paper, a methodology for the quantitative evaluation of graphitic corrosion from the outer surface of pumps by ultrasonic pulse waves is described. As a result of experiment, pulse waves generated by an emitter/sensor on the outer surface are reflected from the corroded inner surface and the height of the echo, which is monitored by the emitter/sensor, is related to the corrosion condition. Based on the field data of 15 cases of pump parts, master curves are developed for the relation of graphitic corrosion condition and the pulse echo ratio. Corrosion condition of a pump parts was evaluated by the proposed method and also by observations of the inner surface after disassembly of 260 pumps. Comparison of these results showed a good agreement.
2010-01-10