ACON Air trampoline packages are designed for year-round use. The frame poles of the trampoline and enclosure are galvanized both inside and outside to prevent rust.
When the safety pad is in place, water cannot get into the poles from the spring holes. If the padding is removed, for example during winter storage, the top rail poles are not connected to the leg poles, so water cannot spread to the lower parts of the trampoline. The spring holes of the trampoline are small, so in any case, only a very small amount of water is able to get into the poles. This small amount of water is able to drain out of the pole joints.
When the plastic caps of the enclosure poles are in place, water cannot enter the enclosure poles. If the plastic caps are removed for example during winter storage, the water drains through the bottom of the pole.
So, water is not able to remain in the poles of the trampoline or the enclosure at quantities large enough that it would be able to harm the poles. In the springtime, any small amount of water left in the poles evaporates. You can read more about winter storage here.