Galvanized (zinc-coated) wire is used in rope/strand to combat the corrosive environments of salt water, atmospheric contaminants, and humid and moist conditions. The combination of strand and wire rope physical properties structures, in some instances giving service lives exceeding 75 years.
Three different zinc coating weights are available to meet a wide range of corrosion resistance requirements. As the life of a zinc coating is proportional to its weight, a heavier coating can be chosen for areas of high corrosion, and a lighter coating chosen for less corrosive atmospheres.
The standard galvanizing is by the hot-dip method, and provides Class A (“double-galvanized”) coating weight (thickness). Heavier coating weights (Class B and Class C) are available. These coatings are applied by electrolytic means only. Class B is twice the weight of Class A coating; Class C is three times the weight of Class A. All coatings conform to the appropriate ASTM Speciﬁcation. Refer to ASTM speciﬁcations A586 and A603 for minimum coating weights.
Zinc, by its nature, protects the base steel wire from corrosion by sacriﬁcial ion exchange. Even minor ﬂaws in the zinc coating will not result in corrosion to the steel base wire, as long as zinc is on nearby wire surfaces.