I am installing a 1000litre jacketed (cooling) tank to mix a 40% caustic solution from caustic pellets. I have a hastelloy tank available. Do you think this is suitable or do I need Monel (Alloy 400) or Alloy 200. The caustic will then be stored in the tank for use.

Some very good information about pelletized and liquid storage of caustic solutions are contained in the OXYchem website.... they have developed a usefull handbook about transport and storage See www.oxychem.com/products/handbooks/caustic.pdf Stay away from bronze, brass, copper lead and aluminum materials in any tank of piping system component. Also see PPG website (another large supplier of caustic pellets) for more info. Hope that this helps MJC

Sir: Alloy C-22 should be very resistant with respect to caustic service. However, almost all corrosion resistant alloys (CRA's) will crack in high temperature caustic, including nickel 200, under severe conditions. Therefore, selecting a material for a pressure vessel for caustic service should include knowledge of specific service conditions as compared with verified laboratory and/or field compatibility corrosion and SCC data and considerations of the risk involved if the vessel were to fail from SCC. Alloys most resistant to aggressive caustic environments include Monel 400, alloy 600, alloy 200 and alloy 201. Nothing is ever black and white with respect to corrosion! Hope this helps! David Hendrix The Hendrix Group Inc.