If I have a 50:50 mixture of ethylene dichloride and water at temperatures from 30 to 250 °C, what's the suitable material of construction for a shell tube heat exchanger? Is stainless steel a good choice? Which is more corrosive to stainless steel, water or a mixture of ethylene dichloride with water? Can carbon steel be used for water and stainless steel for dichlorethane?
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Jim Grant Forum Moderator 120 Posts
Re: What's a suitable material of construction for a shell tube heat exchanger?17 November 2009 at 1:29pmWater is generally less corrosive than dichloroethane or a mixture of the two. However, the presence of low level impurities can significantly change the corrosivity of streams such as these. Low levels of chlorides can cause pitting and stress corrosion cracking of austenitic stainless steels. 316L stainless steel is only recommended for dichloroethane if it is dry. The temperature of 250 °C adds to the challenge as corrosion is usually worse at higher temperatures. In addition, a quick look at the references I have shows that many materials are not suitable for dichloroethane at these temperatures if data is available at all. Once the low level impurities in your streams have been identified, a more thorough review of the literature might reveal some possibilities for materials of construction. Or corrosion tests may need to be run at the temperatures and pressures of concern to adequately address the material of construction issues.