Submerged-arc both-side butt welding method of a square groove

Claim 1

A submerged-arc both-side butt welding method of square grooves between steel plates by using tandem electrodes, comprising the steps of abutting the square edges of steel plates in alignment with each other; applying flux material to one-side surface of the groove thus abutted; moving an electrode assembly through the flux at a speed of 50 to 120 cm/min relative to the plates, said electrode assembly consisting of a leading electrode and a trailing electrode disposed behind the leading electrode, relative to moving direction of the electrode assembly; passing an electric current I1 through the leading electrode to the plates and another electric current I2 through the trailing electrode to the plates, while moving said electrode assembly at said speed, said I1 being 1,000 to 2,000 amperes with a leading electrode arc voltage of ((I1/40)+15) volts to ((I1/40)+35) volts, said I2 being one fourth to four fifths of I1; and repeating said flux application and said movement of the electrode assembly for the opposite side surface of the abutted square groove, in a similar fashion to said one-side.