PURPOSE: To arc-weld tab plates with a good bead shape in the stage of welding the tab plates to four corners of a plate prior to pressing in production of a UO steel pipe by disposing solid materials having specific quality on both sides of the tab plates.

CONSTITUTION: A plate 1 for producing a UO steel pipe is formed by C, U, O forming to a tubular shape and after the joint is tack-welded, the joint is subjected to regular welding from the inside and outside. Tab plates 2 for regular welding are preliminarily arc-welded to four corners of the plate 1 in such a case. Solid materials 4 formed of materials, such as copper, graphite, etc. which do not weld with the steel plate 1 and the tab plates 2 are placed on both ends of the plates 2 in the stage of arc-welding the plates 2 to the plate 1 with the weld bead having high weld strength. The arc is started in the position 5 apart slightly from the material 4 and the arc welding is performed at prescribed welding current and speed. After the arc is stopped just before 5 the other material 4, both materials 4 are removed. The plates 2 are welded to the plate 1 with the good weld bead over the entire transverse length thereof.