Internal welding machine rendering + laser-arc hybrid root welding technology for oil/gas pipelines

In order to improve the construction quality and efficiency of long-distance oil and gas pipelines and reduce the construction cost, an efficient welding method using internal welding machine rendering + laser-arc hybrid welding technology was developed. The internal welding machine has the characteristics of high quality and high speed of root welding, and laser-arc hybrid welding has the advantages of high penetration ratio, small deformation and high speed. Welding experiment was conducted based on the advantages of two equipments. It is indicated that by means of internal welding machine + laser-arc hybrid welding technology, the defects formed on the back of the weld can be controlled effectively, and especially the internal concave on the back of the weld in the direction of 5:00-6:00 is solved effectively. Radiographic testing and mechanical property test were conducted on the welds after welding, and it is shown that they meet the requirements of existing standards. It is revealed from the metallographic image that there are no welding defects in the weld zones, except for some incomplete penetration at the root of the weld blunt edge in the top position. The research results provide the technical foundation for the field application of laser-arc hybrid welding in pipeline construction.