We are looking at a clean-in-place (CIP) tank that will contain the following at ~1% by volume each: 50% Sodium Hydroxide Chlor-Mate Bleach cleaner (contains ~5% bleach by weight and 10 - 30% caustic by weight) Max temperature will be 200 degrees F, but intermittent at that temperature. Can you tell me or point me in the right direction to determine if 304SS or 316SS are adequate for this use or if we need to go to a different alloy?
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Brian Dalder Forum Moderator 175 Posts
Re: What's the best MOC for a clean-in-place tank?12 April 2012 at 1:29pmIn my experience, this is a more difficult question than it might seem. At these concentrations, if there are issues they will be caused by the bleach and not the sodium hydroxide. In general, metallic materials such as 304 and 316 stainless steel are not recommended for use with bleach. However, it is generally believed that there is a point where the sodium hypochlorite is dilute enough such that it is no longer corrosive to stainless steels. Having said this, there is anecdotal information "on the street" that residues left on stainless steels from dilute bleach cleaners may cause staining and corrosion. Assuming the manufacturer of Chlor-Mate is marketing this product as a stainless steel cleaner, I would ask them to provide compatibility data for MOCs, including 304 and 316 stainless steels, at the recommended use concentrations. To minimize risk, you could design your system so that only the amount of CIP solution needed is made up and once used is discarded. This would allow the CIP tank to be rinsed and flushed with water afterwards thereby minimizing the contact time of the tank with the bleach and also minimizing the possible formation of bleach residues.