Continuous galvanizing line

A continuous galvanizing line having an annealing furnace of an all radiant tube heating type, the line comprising:

• a moisture removal device with which an atmospheric gas in the annealing furnace is collected and moisture is removed from the gas and then the gas is returned to the furnace,
• dew-point meters, with which the dew-point of the atmospheric gas is observed, and the outlets, through which the atmospheric gas in the furnace is collected, being placed at least at two points which respectively exist on a side wall in the vicinity of the entrance of the annealing furnace and on a side wall in the vicinity of the furnace top or the furnace bottom at the position where a steel sheet has a maximum end-point temperature, and
• inlets, through which the atmospheric gas from which moisture has been removed with the moisture removal device is fed into the furnace, being placed at two points which respectively exist on side walls opposite to said two points in the height direction of the furnace, and thereby
• making it possible to steadily control the dew-point of the atmospheric gas to be −45° C. or lower and −80° C. or higher throughout the whole area of the annealing furnace.