PURPOSE: To obtain the device for repair-plating the title cutting zone with the adhesion between the repair plating layer and the base material, weldability, etc., improved by increasing the supply of a nonoxidizing gas to a seal hood when continuously calculated values of the dew point and O2 concn. of the atmosphere in the hood exceed a specified value.
CONSTITUTION: The padding on the outer surface of the bead zone 3 of a plated resistance welded steel pipe P is cut by a cutting tool 4, and a nonoxidizing gas is supplied into a seal hood 6 provided on the downstream side of the tool 4 at all times. A molten repair metal having a composition identical or similar to that of the plating layer of a metal-plated band steel S is continuously discharged from a nozzle 5 to the vicinity of the bead cutting zone of the traveling pipe P when the cutting zone of bead 3 is still hot to repair-plate the bead cutting zone. In this case, the dew point and O2 concn. of the nonoxidizing gas extracted 9 to the tool 4 side from the nozzle 5 in the hood 6 are continuously measured 10 and 11' a large amt. of the nonoxidizing gas is supplied 12 into the hood 6 when the measured values exceed a specified value, and the set value in the hood 6 is kept below the specified value when the measured value reaches the set value.
SAITO MINORU
KIKKO TOSHIHARU
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