Gear will sometimes hold together far longer than anyone could reasonably expect. In view of the possible consequences of gear failure, it seems foolhardy to go out with anything but the strongest, best-conditioned rig that is compatible with performance and your purse. Watch, understand, and respond as if it were an instinctive feeling of your inner self. Sometimes metal just plain rusts. Stainless steel rusts more slowly, but tropical climates will get to it in just a few years.
Galvanized steel left untended can dissolve in a matter of months.