Abstract: A method of protecting a metal pipe from corrosion, comprises depositing a layer of nickel composition over both inside and outside of the pipe, and depositing a layer of chrome over the nickel composition on the outside of the pipe. The nickel composition is preferably deposited using an electroless plating, and the chrome is preferably deposited using electroplating. Pipes coated using these methods are particularly useful for sections of exhaust system of a diesel engine having a particulate filter and a selective catalytic reduction system upstream of the coated pipes sections. Straight, bent, and “Y” pipe sections are all contemplated, including large pipes having inside diameters of 4?-8?.

Abstract: An exhaust pathway for an internal combustion engine passes from a larger pipe to a smaller pipe, and then back to a larger pipe. The smaller pipe has a bend of at least approximately 80°, and each of the smaller and downstream larger pipes is disposed within, and spaced apart from, portions of a shell, such that cooling air passes in an air gap between the pipes and the shell.