| 摘要 |
PURPOSE:To prevent crevice corrosion of an underwater article, by adding a chlorine contg. chemical agent in water in the vicinity of the underwater article, all of the part thereof under the water being constituted of stainless steels. CONSTITUTION:For example, when a vertical type pump is used for pumping sea water, in order to hold the suction port 1 and the guide casing 2 thereof to a sufficiently deep site so as to be capable of coping with the change in a water level, the parts of suspension pipes 3, 4 are also arranged under the water surface 7. In this case, the whole of the pump is constituted of stainless steel or a higher anticorrosive material in order to avoid errosion and corrosion caused by a violent water stream generated at the time of the rotation of an impeller 10. In this state, crevices, for example, the mutual connecting parts of the suction port 1, the casing 2, the pipe 3, the pipe 4, a bearing support 6 and a suspension pipe 5 receive corrosion. For the sake of preventing corrosion, NaClO is added to sea water in the vicinity of the pump. By this method, the natural electrode potential of stainless steel in sea water is transferred to a negative side as the concn. of NaClO is increased and the corrosion of the crevice can be prevented. |
