Corrosion resistance of galvanised coatings in rural environments: retrospective evaluation

Abstract

The steel used in high tension electricity pylons is usually protected against corrosion by hot dip galvanising. Because the majority of the material is exposed to rural conditions, its life span is satisfactory and it requires no maintenance. The life of the zinc coatings may initially be regarded as proportional to their mass regardless of the coating procedure used. This simplification hides the reality of differences in behaviour related to the structures of the coatings, and may result in different values for varying corrosive sources which are not always simple to identify. The present paper analyses the state of zinc coatings on steels which have been exposed to the elements for periods of 18–19 years in rural environments in Spain. The coatings with a richer iron structure resisted corrosion more effectively.