Mechanism of corrosion

  • How is red-rust developed?

    ・Development of red-rust starts when iron of water pipe releases electrons and iron ion is dissolved into water.

    Fe Fe2+ + 2e-

    ・Red-rust “FeO(OH)” is developed when iron ion is reacted with Oxygen(O2) and water (H2O)

    4Fe + 3O2 + 2H2O 4FeO(OH)

    ・Red-rust dissolves into water and causes red-water, clogging, degrade the pipe and eventually causes water leak.

  • How to stop development of red-rust

    ・In reverse, red-rust development can be stopped if electrons are supplied to the iron that has just lost electron.

    4Fe + 3O2 + 2H2O 4FeO(OH)

    ・It is called “Electrolytic Protection”

    Electrolytic Protection is the only way to completely stop development of red-rust.

  • How to reduce red-rust to magnetite.

    ・Existing internal red-rust can be reduced to magnetite by continuous supply of electrons.

    6FeO(OH) + 2e- 2Fe3O4 + 3H2O + 1/2O2

    Magnetite is called “Passive State” material. It is very resistant to oxidation; it does not dissolve into water and is only 1/10th cubic size of red rust.

    Magnetite provides protective barriers to inner wall of water pipe work. And extends life time of water pipe work for more than 40 years.

    Red-rust Black-rust

    Electrolytic Proatection is the only way to convert red-rust to black-rust.

  • Problems of Conventional Cleaning Work

    ・Conventional cleaning work such as sand blasting or chemical cleaning remove existing red rust which flows out from the pipe work.

    ・It temporally solves the problem of internal blockages or red water discolouration within the pipe work.

    ・On the other hand , it is loosening the material inside the pipes and reduces the inner wall thickness of the pipe work.

    ・Also it increases inner surface area of the water pipe work and accelerates future development of red-rust, which shortens the life time of the water pipe work.

    Pipe Thickness Cleaning Thickness gets thinner