ステンレス鋼配管のすき間腐食に及ぼす鋼種およびガスケット材質の影響

抄録

The Influence of steel composition and insulating gasket materials on the crevice corrosion of stainless steel piping has been investigated through the loop test and the polarization measurements in 5% NaCl (pH=3.0) at 50°C.
The result of the loop test showed that the crevice corrosion tendency was markedly varied with the composition of stainless steels and of gasket materials attaching to the steel. For the stainless steel composition, the tendency decreased in the order: SUS 24, SUS 28, SUS 33 and 18Cr-16Ni-5Mo. For the gasket material, it decreased in the order: chrysotile asbestos, blue asbestos, SBR and Teflon.
The polarization measurements were also made on the stainless steel specimen (crevice-free) and that coupled with gasket materials (crevice-containing). The current density ratio-potential curves showed the same tendency obtained from the loop test. The larger the ratio in the potential range from passivation to pitting potential, the larger the crevice corrosion tendency of the couple of a stainless steel and a gasket material.
The variation of the crevice corrosion tendency contributed by the gasket materials can be explained mainly on the swelling nature when immersed in the environmental solution, and on the adhesional wetting nature of the surface.