Method for determining the linear AC electrical resistance of a steel pipe and device for implementing such a method

A method for determining a linear electrical resistance in AC mode of a steel pipeline, comprising the steps of:

• a) generating in a portion of the steel pipeline an induced current resulting from production of a magnetic field at a predefined frequency by means of an induction coil centered on a longitudinal axis of the steel pipeline and traversed by an AC current, the induction coil being housed in a yoke made of ferromagnetic material in order to confine the magnetic field to a predefined surface of the steel pipeline portion;
• b) measuring an active power dissipated by the steel pipeline portion subjected to the magnetic field;
• c) determining an amplitude of the produced magnetic field;
• d) determining the linear electrical resistance in AC mode of the steel pipeline portion from the measurements of the dissipated active power and the amplitude of the produced magnetic field, the linear electrical resistance in AC mode of the steel pipeline portion being determined in step d) by the following equation:
• RAC_DEH=(2×Πheat_JIMP)/(π×OD×HJIMP)2;
• where RAC_DEH is the linear electrical resistance in AC mode, Πheat_JIMP is the active power dissipated by the steel pipeline per unit length, OD is the diameter of the steel pipeline, and HJIMP is the amplitude of the produced magnetic field;
• and
• e) commissioning the steel pipeline portion when the determined linear electrical resistance in AC mode of the steel pipeline portion is within a tolerance to provide homogeneous heating power throughout the steel pipeline.