This report describes a deperming technique for reducing of the are blow ef
fect in DC welding of ferromagnetic pipelines. The technique is based on co
mpensation of the axial field in the welding gap by a re-magnetization of t
he pipe near the joint. The re-magnetization is produced with a coil set dr
iven with a bipolar impulse, We examined an axisymmetrical model of the pip
es with commercial finite element software (ANSYS). The model has plane sym
metry in the middle of the welding gap, Initial magnetization levels in the
model were determined from a preliminary experimental investigation of an
oil pipeline in Ukraine, A prototype of the deperming device was fabricated
, including a coil set, an impulse power supply and a magnetometer, A magne
tic measuring procedure was also developed to optimize the transient curren
t in the coils, Our experimental results have confirmed the efficacy of thi
s deperming technique, which provides an acceptable level of the magnetic F
ield in the welding gap.