The invention discloses a pipeline multipoint synchronous automatic
welding process used for root
welding conducted through an inner
welding machine. The process is designed for increasing the welding speed. According to the
welding process, the eight-welding-
torch pipeline synchronous automatic welding inner welding
machine is adopted, a first welding gun, a second welding gun, a third welding gun and a fourth welding gun are used for segmented independent welding on the side
ranging from 0 degree to 80 degrees of a pipeline, the fifth welding gun, the sixth welding gun, the seventh welding gun and the eighth welding gun are used for segmented independent welding on the side
ranging from 180 degrees to 0 degree of the pipeline, and the welding directions, on the two sides of the pipeline, of the welding
machine are opposite. The process includes the steps that a specially-designed U-shaped groove is formed in the end of the large-
caliber oil and
gas pipeline; the inner welding machine is aligned with the pipeline; welding parameters of the inner welding machine are adjusted; root welding of the groove is conducted through the inner welding machine; thermal welding, filling welding and cosmetic welding of a weld joint are conducted; after the whole annular joint is welded completely, an arc is quenched. In the
welding process, the U-shaped groove of the weld joint is small, the volume needing to be filled is small, the welding speed can be increased three to four times, and construction efficiency is improved to a great extent.
Welding stress can be evenly distributed through segmented multipoint synchronous welding, potential safety hazards caused by
stress concentration are eliminated, and the welding pass percent is kept over 97%.