Method provides welders new technique for avoiding arc blow

A new method has been formulated that allows welders with little background in magnetism to reduce arc blow during DC welding of pipelines. Technicians took several measurements of the residual magnetic field of pipelines in southern Mexico. A Magnet-Physik FH-51 Gaussmeter took magnetic flux density measurements of 8, 10, and 30-in. OD pipelines. FEMM helped develop an axisymmetric model of the pipeline with a coil of n-turns. FEMM is a freeware program for electrostatic and magnetic finite-element simulations in two dimensions. The simulation process used 16-m pipe sections with a groove consistent with dimensions dictated by API-1104. The first step of the welding process is to adjust the current through the electrode to obtain the optimum arc length. The operator will always know in advance the range of current to be used for a specific welding task according to the electrode selection.