What grade steel is it? Most low carbon steels (ASTM A36) are pretty durable even if placed in an environment where they will rust. What you will need to take care of are the welds - welding creates heat affected areas in metal which are very susceptible to repeate loadings and temperature extremes. This can be especially true if they are shop, non qualified welds.
There isn't much you can do for them, except hope the guy ran a correct depth bead and welded it with correct filler electrode material.