Author(s)

T. Kuraoka & Y. Sato

Abstract

Zinc-coated stranded steel wires are widely used for messenger wires of the overhead catenary system. Though these wires have been uniformly replaced mainly based on aging, the corrosion speed of the wire, which is the main factor of the degradation, is thoroughly different depending on the installed environment. The purpose of this study is to propose a replacement period of zinc-coated stranded steel wire according to the installed environment. In order to investigate the corrosive situation of the messenger wire under the current environmental conditions, we carried out the measurement of the residual amount of zinc and iron of the wire installed under various environments by using a deterioration detection device as developed by our laboratory, and examined the relation between corrosion and aging. Consequently, the estimated period for the zinc plating elimination was twenty years in seashore areas, thirty years in city areas, and fifty years in mountainous areas respectively as the lower estimate. On the other hand, there was almost no reduction in iron remains in every environment because of the anticorrosive effect of zinc on iron. Moreover, we carried out a tensile test and a vibration test in order to evaluate the relation between corrosion and the mechanical characteristics of zinc-coated stranded steel wires for which corrosion was accelerated by using the salt spray test system. As a result, the vibration fatigue characteristic of the wires greatly deteriorated when iron corroded. From these results, it was evident that the limit of service life of messenger wires should be set at the time point when the zinc plating disappeared. Furthermore, we confirmed that the ACM (Atmosphere Corrosion Monitoring) sensor was useful as a method to estimate the corrosion rate of zinc plating in each environment in a short period. Keywords: corrosion, zinc-coated stranded steel wire, messenger wire, salt spray test, atmosphere corrosion monitoring sensor.

Keywords

corrosion, zinc-coated stranded steel wire, messenger wire, salt spray test, atmosphere corrosion monitoring sensor.