The invention relates to a machinery arrangement, which comprises a combus-tion unit (3) arranged in an engine room (11), and an exhaust gas duct assem-bly (4) connected to the combustion unit (3) for receiving an exhaust gas flow and for leading the exhaust gas flow to the atmosphere through an exhaust gas cleaning system (5) provided with an exhaust gas pipe (52). In order to condi-tion the exhaust plume, the exhaust gas pipe (52) is arranged in an enclosure (114), whereby the enclosure (114) is arranged in flow connection with the en-gine room (11) in order to provide heat for the exhaust gas pipe (52) by means of a heated air flow from the engine room.