The temperature of the air can have a significant effect on the corrosion rate of some materials, but hot-dip galvanized steel does not show significant differences at very low temperatures, below -40 F, or at very high temperatures, above 150 F.
However, very high temperature environments can have an affect on galvanized steel. These effects depend on the time exposed and the severity of the environment. When considering long-term exposure, the recommended maximum service temperature is approximately 390 F (200 C). Problems that could occur from long-term exposure to temperatures above this level include peeling. Peeling is caused by closely spaced voids that expand and form a gap, it causes the outer free zinc layer to split-off from the underlying zinc-iron alloy layers. However, the remaining zinc-iron alloy layers will still provide a high level of corrosion protection for many years.
At temperatures ranging between 390 F (200 C) and 480 F (250 C), the zinc-iron alloy layers will continue to protect the steel from corrosion. High temperatures above 480 F (250 C) will accelerate peeling and continued exposure can result in the zinc-iron alloy layers cracking and separating from the steel. Temperature applications of hot-dip galvanized steel above 480 F (250 C) are not recommended.
When considering short-term usage, that is, periods of less than two hours at a time or onetime temperature excursions for less than twenty-four hours, the recommended maximum service temperature for galvanized steel is approximately 660 F (350 C).
Studies done on the effect of low temperature environments on HDG steel indicate minimal change in the behavior of the galvanized coating. Some polar installations have used HDG steel for corrosion protection and have been in service for many years. As with any steel at very low temperatures, the material becomes brittle with extended use. Low temperature climates are an appropriate use for hot-dip galvanized steel.
