Abstract: An exhaust duct for use with a direct evacuation exhaust decontamination system of a blast furnace or steel converter. The exhaust duct includes a main support coolant inlet conduit and a plurality of coolant return conduits arranged in a generally circular pattern to define an exhaust duct having a circular cross section for the evacuation of exhaust gases from a furnace. The inlet conduit and the return cooling conduits are connected to a distribution manifold on one end so that all of the coolant enters the exhaust duct through the main coolant supply conduit and is returned and discharged through the smaller cooling conduits which thereby serve to maintain the exhaust duct at a relatively low temperature to prevent oxidation or destruction of the duct walls by the exhaust gases. The discharged coolant may be directed into the exhaust gases at the end of the exhaust duct for use in a "wet" exhaust cleansing system or collected in a trough or manifold when used with a "dry" exhaust cleansing system.