A heat treating furnace has a reaction tube for accommodating an object to be treated, a heating device arranged to surround the reaction tube, a heat-insulating member arranged outside the heating device, a tubular member arranged outside the heat-insulating member, and a coolant circulating pipe arranged...http://www.google.fr/patents/US5171972?utm_source=gb-gplus-shareBrevet US5171972 - Heat treating furnace
