Abstract: A method for minimizing corrosion and the build-up of deposits on surfaces of a flue-gas system exposed to moist substances and elevated temperatures, and particularly those surfaces which are used to convey other additives to the system and the surfaces of gas/gas heaters which receive the output from scrubbers, which method involves adding to the system, particularly in those conduits and at the surfaces of the gas/gas heater, generally inert bulking agents such as perlite and vermiculite in expanded form, such agents, apparently by acting under the operating conditions to which they are subjected to retain substantial quantities of water without becoming dissolved, accomplishing the desired results.