METHOD FOR REPAIRING A DRILL PIPE

The invention relates to welding and overlaying and can be used for recovering worn-out parts of pieces like solids of revolution, in particular drill pipes. The inventive method for repairing a drill pipe (1) consists in forming a bead submerged under a flux (6) on the surface of the worn nipple (3) and coupling (4) parts of the pipe (1) by means of automatic electric arc welding during the tube (1) rotation and in displacing electrodes (5) back and forth along the generatrix of the tube, wherein, prior to overlaying, the electrodes (5) are offset-positioned in a horizontal plane oppositely to the pipe (1) rotation at a linear deviation of 20-30 mm from zenith and at an angular deviation of 18-26° therefrom, the overlaying is carried out with a straight polarity when a minus is connected to the electrodes (5) and a plus is connected to the pipe (1), the group of electrodes (5) used for overlaying the nipple part (3) of the tube (1) is fed from one power supply, the group of electrodes (5) used for overlaying the coupling part (4) of the pipe (1) are fed from another power supply, the space between electrodes (5) of each group is selected according to a condition consisting in forming a common bath of melt metal along the total width of the overlayed bead, the electrodes (5) are displaced simultaneously with the supply of the flux (6), the pipe (1) is cooled from inside and from the end faces thereof during the overlaying and the overlayed areas are thermostatically controlled. The overlayed surfaces are exposed to ultrasound treatment. L'invention concerne le soudage ou le rechargement par soudage et peut s'utiliser dans la remise en état des parties usées de pièces de type de corps de rotation, notamment de tiges de forage. Le procédé de remise en état d'une tige de forage (1) consiste à former un boudin sur les surfaces usées des parties de raccord (3) et de manchon (4) de la tige (1), par procédé de rechargement à arc électrique automatique sous flux (6) en assurant la rotation de la tige (1) et le déplacement des électrodes (5) dans le sens aller et retour par rapport à sa génératrice. Avant d'effectuer le rechargement, on monte les électrodes (5) avec un décalage sur le plan horizontal contre le sens de rotation de la tige (1), avec un décalage linéaire par rapport au "zénith" de 20-30 mm et un décalage angulaire par rapport au "zénith" de 18-26°. Le rechargement s'effectue sur la polarité directe, par le branchement du "moins" sur les électrodes (5)