Effects of chlorine dioxide on 316 stainless steel

A. 316 stainless steel will be slightly less prone to corrosion than 304, but chlorine dioxide is pretty nasty stuff. It is a very powerful oxidising agent and in an aqueous solution will still attack most metals. It will also break down to oxygen and chlorine, that will ultimately form hydrochloric acid. This will cause pitting corrosion of the stainless. You may want to consider using a plastic pipe (perhaps PTFE or Poly Phenylene Oxide) as an alternative; these should not be so susceptible.

A. Dear Ray, why do not use titanium. As for chlorine dioxide it is well known the metal is the best choice. See pulp and paper industry plants where titanium is greatly used for bleaching towers and various heat exchanger. Recently I myself delivered the item for Svetogorsk p&p plant, for example. Please decide.

Sincerely your,

A. Perhaps the enquirer has got his chemicals mixed up. First, there is reference to hot water, and then to chlorine dioxide at 1.1mg/l. There is no reason to have "chlorine dioxide" in hot water, and you certainly would not use Type 304 in a chlorine dioxide system. I suspect this is simply just hot chlorinated tap water with a "chlorine" content of 1.1mg/l. The answer is generally, yes, Type 316 will perform better in hot chlorinated tap water with a free chlorine content of 1.1mg/l(ppm).

A. Chlorine Dioxide is most commonly used for legionella control in domestic water systems. While the concentrations are significantly lower to maintain bacteria control vs. regular chlorine, it does attack 316 leading to heat exchanger failures. The engineer did not 'mix up' his chemicals.