METHOD FOR CONTACT-BONDING UNBONDED PART OF COVERING COATING LAYER SKIN IN COVERINGLY COATED STEEL PIPE

PURPOSE:To automatically and firmly contact-bond the unbonded part of a cover coating layer skin developed near a bead part to a pipe body at the cover coating of the outer peripheral surface of a steel pipe by a method wherein the contact-bonding position of a roll is controlled by continuously detecting the passing speed of a steel pipe, the position of a pipe end, the position of the bead part from the pipe end and the position of the bead part in the peripheral direction of the pipe. CONSTITUTION:The lifting timing of a pressure roll 16 is controlled by signals, which are detected with a steel pipe line speed detector 13 and a pipe end detector 14. The positioning of the pressure roll 16 and the following-up of the pressure roll 16 to the unbonded part is done on the basis of the signal, which indicate the position of a bead part from the pipe end, and the signal, which indicates the position of the bead part in the peripheral direction of the pipe, both of which are detected with a bead part detector 15, so as to contact-bond the unbonded part of the covering coating layer skin of a coveringly coated steel pipe. When the end of the coveringly coated steel pipe reaches the pressure roll 16, the pressure roll 16 is pre-set at the first position of the unbonded part of the covering coating layer skin. Just after the arrival of the bead part to the pressure roll 16, the pressure roll 16 is lowered so as to contact-bond the unbonded part of the covering coating layer skin of the steel pipe to a pipe body.