Corrosion staining from stainless steel swimming pool step poles was observed on the concrete decking supporting the stainless steel step poles. An overall view of the staining is shown in Photograph A
Photograph A Concrete pool ladder support.
The stainless steel swimming pool step poles were removable and were set into a cup receiver as shown in Photograph B.
Photograph B Corrosion on inside wall surface of receiving cup.
The stainless steel poles were chemically analyzed and were found to be type 304L stainless steel as prescribed in the construction specifications. The bottom of the pole receiving cups, shown in Photograph B, were solid without drainage capability. Chlorinated pool water, which washed into the receiver cups, remained and concentrated the chlorinated water. The bottom of the stainless steel ladder poles were subject to concentration cell corrosion and pitting attack of the stainless poles by chloride in the swimming pool water.
The rusty corrosion product and concentrated chloride pool water was forced up and around the receiver cup lip and stained the concrete decking. Stainless steel in a chlorinated environment will most likely always result in corrosion.