procedure and device for controlling cooling of a svetsfog

摘要

The present invention concerns a method to monitor the cooling process in a welded joint during the welding of pipes (1) of a weldable polymer material, where the welding process comprises that a muff (7) of a weldable polymer material is placed with overlap over the end of the pipe, and that an electrically conducting tape (9) is placed between the pipe and the muff, that the muff is held in place by welding equipment (19) that makes contact with the muff, and that the muff is welded to the pipe through an electrical current being supplied in order to heat the tape and the surrounding polymer material in order to form a welded joint, where a measurement process is carried out after the welding process has ended comprising that a current pulse Ip is supplied to the tape from an indicator unit (40), a resulting temperature-dependent parameter Sp in the tape is determined by the indicator unit, the value of Sp is stored in the indicator unit, that a further current pulse Ip is supplied to the tape from the indicator unit after a predetermined time interval, and that the parameter Sp in the tape is determined and the value of Sp is stored in the indicator unit, the indicator unit monitors and evaluates the value of the parameter Sp or the relative change in the value of the parameter Sp, the measurement process is repeated until Sp reaches a plateau value or the relative change in Sp reaches a predetermined level, a signal arrangement signals that the welding equipment can be removed from the area of the weld when the indicator unit (40) indicates that the cooling process has ended. The invention concerns also an arrangement for monitoring the cooling process during the welding of pipes of a weldable polymer material.