Kurita Water Industries Ltd.

Hajime Iseri

Yutaka Yoneda

Kuniyuki Takahashi

Shintaro Mori

The present invention provides a corrosion inhibition method which minimizes environmental adverse effects by using phosphate base anticorrosives without using zinc salt base anticorrosives and by reducing the concentration of the phosphate base anticorrosives, enables stable formation of an effective initial protective film, and does not affect water treatment after the formation of the initial protective film. In an initial protective film formation process of forming an initial protective film on a surface of an iron-based metallic member of a water system by adding anticorrosives to the water system, at least one selected from a group consisting of pyrophosphoric acids and pyrophosphates is employed as the anticorrosives and the initial protective film formation process is conducted such that the initial pH at the start of the initial protective film formation process is adjusted to be 5 or more and less than 7 so that the pH at the end of the initial protective film formation process becomes 7 or more.

Corrosion inhibition method

According to the method of treating water in a cooling water system, adhesion of fouling is on-line monitored by a compact and inexpensive apparatus and a slime control treatment is intensified according to the result of on-line monitoring. The water treatment is intensified in response to the change of electric potential of a sensor monitoring microbial fouling made of sensitized metallic material. When the electric potential of the sensor exceeds a threshold value, an agent is added through both chemical feeding pumps and When the electric potential lowers to the normal value, the agent is added only through the pump

Method of treating water in a water system

Corrosion of a metal member under heat transfer condition is monitored by using a test coupon made of the same material as that of the metal member. The test coupon may have a welded portion and a crevice. One substantial surface of the test coupon is heated by a sheet shaped heating element, and at least one portion of the other surface of the test coupon is contacted with the corrosive fluid. After detecting a status of corrosion of the test coupon, the corrosion of the metal member is monitored based on the results of the detection. In case a counter electrode or reference electrode is used, the electrode is immersed in the corrosive fluid, and electrical signals between the test coupon and the electrode are measured. Then, the corrosion of the metal member is monitored.

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Tokyo, Japan

Hajime Iseri