METHOD FOR PREVENTING CORROSION IN BOTTOM PLATE OF TANK

摘要

PURPOSE:To completaly prevent the corrosion in the bottom plate of a tank and to make the bottom plate maintenance-free by using base soil having a specified water content and chlorine ion concn. and a tank bottom plate having a zinc thermal spray film with the specified thickness on a back. CONSTITUTION:A base soil having <=15% water content and <=500ppm chlorine ion concn. is used as the vase soil for a tank. A steel sheet having a zinc thermal spray film with 100-500 mum thickness on one surface is used as the bottom plate with the film side as the back. The steel sheet with thermal spray Zn film has extremely good corrosion resistance when the soil has <=15% water content, but the corrosion resistance is deteriorated when the soil has >15% water content. This property is vigorously increased when the soil contains >500ppm chlorine ion concn. Thus, the soil is specified to have <=500ppm chlorine ion concn. Thickness of the zinc coating film of the steel sheet is necessary to be 100mum if considering a 10-year service life. When the thickness of the film exceeds 500mum, adhesion property with the steel sheet is decreased to cause peeling.