As the Higashi Shinagawa bridge section is located on the Keihin Canal, the piers that come in direct contact with the seawater are subject to severe chloride damage. As the structure to be built in this project is required to have a useful life of 100 years, it was necessary to protect the pier from corrosion.

Applying a stainless lining is a corrosion prevention method in which the material to be strengthened is covered with rust preventive stainless steel. In this project, the stainless lining was used to protect the base of the pier from splashing seawater or the part of the pier that remains immersed in seawater. Because the stainless lining prevents the steel piers from coming in contact with corrosive agents such as water and oxygen, it boosts their corrosion resistance and reduces the lifecycle cost. This is normally used to protect harbor structures of critical importance. The method was also adopted for steel jacketing the D-Runway of the Tokyo International Airport (Haneda Airport). This has been used for 26 piers and a series of bridges for the first time in this construction work under the Shutoko project, even though it has already been used twice in the past for the construction of Namamugi JCT and Komatsugawa JCT respectively.
The stainless lining has been used for structure elevations ranging between L.W.L (Low Water Level) -1 m to H.W.L (High Water Level) +1 m. The steel material used for lining is SUS312L, a type of Austenitic stainless steel that is 1.5 times stronger than ordinary stainless steel (SUS304), and the thickness of the steel plates is 1.2 mm, same as that of the plates used for the Tokyo International Airport (Haneda Airport).

< Stainless Steel Lining on the Bridge Pier Base >

As the part of the pier in contact with the atmosphere is constantly subjected to airborne chloride, it has been sprayed with Al- Mg alloy thermal spray (metal thermal spraying) in addition to the application of a thick anti-corrosive coat to protect the structure against corrosion for at least 100 years. Metal thermal spraying is the process of preventing corrosion of steel by coating it with a film of molten metal which rusts before the primary steel itself. By thermal spraying molten metal on the steel structures erected in sea, their corrosion resistance can be increased to 4 times that of the steel structures protected only by a thick anti-corrosion coat, which is thicker than the one normally used to protect the steel structures erected in sea.

<Al-Mg Metal Thermal Spraying in Process>