To establish all-position electron beam welding conditions for 19 mm thick API 5L-X65 pipe, in the previous report, appropriate welding parameters to obtain acceptable weld bead quality were clarified in eight representative welding positions.
Based on that result, all-position continuous welding trials were carried out by turning an electron gun inside the test pipe to be welded. Welding parameters such as the welding speed and the beam focusing condition were continuously changed, by tracing proper conditions at eight positions located by 45 degrees' interval. By using that method, all position welding has been completed successfully, and acceptable weld bead quality was obtained throughout the circumference.
Dimensional tolerances of the pipe setting for the acceptable weld bead formation was investigated by welding test pipes with various gap and mismatch values. Subsidence of weld metal, called under-fill, was observed, when the gap exceeded 0.2 mm. On the other hand, the mismatch up to 2.5 mm did not cause a surface defect of the weld bead.
