実石油タンク底板への亜鉛溶射鋼板の適用条件最適化--石油タンク底板の防食技術の開発 第五報

摘要

Large efficiency of Zn sprayed steel plate for enhancement corrosion lifetime has been investigated in previous paper. To apply Zn sprayed steel to bottom plate of industrial oil tanks, weld work being essential for building affects metallic condition and corrosion preventive property of Zn layer largely. To avoid detrimental effect of welding, numeric heat input analysis and corrosion test of heat affected zone on Zn sprayed layer was carried out to find optimum utilizing conditions in this study. As a result, it is found that the surface temperature goes above melting point of zinc easily resulting oxidization of outer surface and formation of Fe-Zn alloy layer that are detrimental corrosion. And it is also found that limiting heat input of welding to 0.6kJ/mm at filet welding with 9. 0 mm thickness enables to minimize the damage to the Zn sprayed surface. Based on this finding, corrosion test of Zn sprayed plate with weld, with which heat input control at welding was carried out. Weld sample with the heat input control has shown good corrosion resistance. Based on findings above, building of bottom plate for 30,000k l industrial oil storage tank utilizing Zn sprayed steel plate has been completed successfully.