Hello, Rajendran-- The application you mention has received much attention in past 25 years . The key problems are that stainless steels are subject to pitting in chlorides , and that in flue gas the tendency exists for the gas to condense on the surface and Cl concentrations to increase . Two free online references will provide a good start , but you will need data on temperatures , and composition of exhaust before even a consultant can make a good selection : http://www.corrosionsource.com/technicallibrary/nidi/literature/pdf/10020.pdf http://www.alleghenytechnologies.com/ludlum/pages/products/xq/asp/P.14/qx/product.html [for this one , click on "Technical Data Blue Sheet"].