Effect of the Variation of Coating Thickness on the Performance of Steel Wires Used in OPGW Cables

摘要

The performance and lifetime of an OPGW cable depend on several factors and processes. The process starts with the steel wire surface preparation for galvanizing, that is, cleaning and pickling. During the galvanizing step, a great deal of attention must be paid to the preparation and maintenance of the zinc bath, mainly its temperature. A good surface and bath preparation will assure uniform and adherent coating. In the cable manufacturing and installation step, the wires are stressed which damage the coating layer. In the field, the OPGW cables are exposed to aggressive agents, including those from the environment and those related to installation, maintenance and operation. The defective spots become prone to corrosion and, depending on the extent of such defects; this may result in mechanical damage. Therefore, it is important to estimate the minimum thickness of the zinc layer necessary to maintain its mechanical strength and corrosion resistance, as well as to evaluate the micro structural characteristics of the galvanized wire. This paper describes the preparation of defects different size in the coating of wires from 2.67 to 3.09 mm diameter. Several mechanical, climatic, thickness measurements and thickness uniformity tests have been carried out on the wires, which were then assessed by scanning electronic microscopy, in order to evaluate the influence of defects on the mechanical performance and on the corrosion behavior.