JAP It is difficult to give a straight answer. Question should be specific with details How and what is the design code, materials used, have to be known. Design parameters for cooling water flow - the inlet, the outlet, baffle locations i.e., What is the cooling water flow at the inlet, exit ends? What is the tube side design - process parameters, temperature, pressure. How many years the exchanger has been in this service and the failure analysis / diagnosis over a period of time ? How many passes are there in the exchanger, whether fixed or floating type, whether it is a "U" bundle or straight tube? What is the material used for tubes? What is the cooling water control done in the plant? How is the cooling water analysis done? Outside of tubes - where it is affected- has to be ascertaiend. Whether the failure is close to the bottom tube sheet or at the inlet end or at some mid point areas? Whether the tubes are affected over-all with general corrosion ? Based on the study and input only the cause can be identified to give any opinion. All parameters have to be studied, by you, or engage a consultant experienced in this, very carefully before giving any opinion. Trust this answers your query C.V.Srinivasan Nishi Engineers pvt Ltd Chennai India Nov 6 E-maiil: nishi@vsnl.com/nishi@hathway.com >Hello >Has anyone experienced corrosion on outside of tubes in a >shell and tube exchangers with cooling water on the shell >side. Our exchanger is vertical with horizontal baffles. Pl >advise remedies.