FINISHING METHOD AND APPARATUS FOR CONVENTIONAL HOT DIP COATING OF A FERROUS BASE METAL STRIP WITH A MOLTEN COATING METAL

FINISHING METHOD AND APPARATUS FOR CONVENTIONAL HOT DIP COATING OF A FERROUS BASE METAL STRIP WITH A MOLTEN COATING METAL A finishing method and apparatus for conventional continuous hot-dip coating of the type wherein a ferrous base metal strip (9, 54, 68, 81, 99) is caused to pass beneath the surface of a coating bath (7, 49, 65, 73, 86, 102) of molten coating metal and is thereafter subjected to jet finishing, the ferrous base metal strip having been appropriately pretreated so as to be at the proper coating temperature and so as to have its surfaces oxide-free when passing through the bath of molten coating metal. The method comprises the steps of providing an enclosure(27, 53, 60, 76, 87) for the two-side coated strip as it exits the coating bath, locating a finishing jet nozzle(28, 29, 55, 56, 61, 62, 79, 80, 91, 92) to either side of the coated strip within the enclosure, jet finishing the coated strip with a non-oxidizing or inert gas and maintaining the jet finishing gas and the atmosphere within the enclosure at an oxygen level of less than about 200 parts per million. The apparatus comprises the above mentioned enclosure with the jet finishing nozzles located therein and an appropriate system (34, 39-45, 64, 78, 90) to provide a non-oxidizing or inert atmosphere within the enclosure.