Analysis of Corrosion Causes of Ring Connection Fittings of ±800 kV Transmission Line

Abstract

The ring-linked fitting used in an ultra-high voltage DC transmission line project has suffered serious local corrosion after only one year of operation. Based on the macroscopic inspection, chemical composition analysis, galvanized layer quality analysis, metallographic organization analysis, scanning electron microscopy analysis, and energy spectrum analysis, the physical and chemical examination of the ring coupling fixture was carried out to analyze its corrosion causes and explore the corrosion mechanism. The results show that the galvanized layer of the rusted area was damaged by wear and tear due to external factors in the process of transportation, lifting, and installation. And the electrochemical corrosion led to the serious local corrosion of the fixture within a short period of operation. It is recommended to send someone to visually check the shape of the galvanized layer of the metal before the ring-linked fixture is put on the tower and to review the thickness of the zinc layer at the end of the fixture with a handheld zinc layer thickness tester if necessary.