Stainless Steels in Indoor Swimming Pools

The paper discusses the risks of stress corrosion cracking (SCC) in suspended ceilings and other load bearing structures in indoor swimming pool environments (including hotel pools and health clubs). The standard austenitic stainless steel grades 1.4301 / 1.4307 (304 type) and 1.4401 / 1.4404 (316 type), which have a track record of excellent performance in areas permanently wet by the pool water, are, however, susceptibale to stress corrosion cracking under atmospherical conditions typical of indoor swimming pools. Repeated cycles of evaporation and condensation can lead to deposits with cloride concentrations several times those of the pool water itself - even in areas of the building remote from the pool. It occurs when such grades are exposed to the combined effects of tensile stress and chloride exposure. SCC is characterised by the fact that failure may occure without previous visible signs of corrosion, which makes it a point of concern. The paper recommends alternative grades, specifically with a high Nickel content as well as grades with an austenitic-ferritic (Duplex) structure. Their suitability for structural applications has been proved in exposure tests, which are also reflected in some national and European building codes.

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