PURPOSE: To prevent a welding defect from the first layer and to improve welding efficiency with a joint which get wet in the rain in the stage of butt welding said joint using a backing strip by limiting the space between the base metal and the backing strip for welding the first layer and the bulk density of a flux.
CONSTITUTION: The space between a backing strip 4 and the rear surface of a base metal 1 is set at ≥1mm and ≤2mm and the first layer is subjected to submerged arc welding by using a flux having ≤1.2g/cm3 bulk specific gravity. The submerged arc welding is executed for the 2nd and succeeding layers in the same way as in the prior art. The backing strip 4 provided with a groove 8 having a depth G by machining is used or the backing strip 4 on which spacers 9 having a thickness G are placed at a specified interval is used in order to maintain the space between the metal 1 and the strip 4 within the above-described range.
IKEDA SHINICHI
KISHIDA HITOSHI
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