How do steel Coils Get Wet?

Coils or bundled sheets get wet in two ways:

1.Water from rainfall gets between the sheets while the product is in transit or while it is sitting at a jobsite

2.Condensation.

Condensation occurs when the coil or stacked sheets are below the dew point of the local atmosphere. One way for this to occur is when coils are shipped in the wintertime, and then placed into a warehouse that is warmer than the galvanized steel and where the humidity is not at a controlled low level. Under these conditions, the moisture simply condenses onto the steel’s surface as the “cold coil” causes the local air temperature to drop. This is similar to the condensation of moisture onto a cold windowpane.

Condensation can occur in other ways that are not as obvious as that above. For example, even if the coil temperature and the temperature inside the local warehouse are about the same when the coil arrives at a customer’s plant, but the warehouse is not temperature controlled, cooling overnight might allow condensation to occur between the adjacent wraps. Once moisture condenses, it takes a long time for the moisture to dry because there is so little air movement between wraps in a coil or bundle.

Because there is no absolute way to totally prevent storage stain once the material gets wet, it is important for the best practices to be applied at all steps in the process.