On August 14, the fully automatic argon arc external root welding technology initiated and researched by Jianghan Petroleum Construction Company was successfully applied to the Section VI Project of the East Trunk Line of Shandong Pipeline Network undertaken by the company, with a one-time welding qualification rate of 98% for the trial welding of one hundred pipe joints.
At present, combined automatic welding technology is generally adopted for large-diameter, high-grade steel pipelines during mountain construction and tie-in operations in China. Specifically, manual argon tungsten arc welding is used for root pass welding of pipe orifices, while flux-cored wire full-automatic welding is applied for filling and capping passes. Nevertheless, this technology is plagued by drawbacks including long welding cycles and inconsistent welding quality.
Take a pipeline with an outer diameter of 1219 mm and a wall thickness of 18.4 mm as an example. It usually takes 4 hours to weld one joint, among which the manual root welding alone takes more than one hour. The welder's skill, physical stamina and working environment all exert impacts on welding quality.
In 2021, Jianghan Petroleum Construction Company put forward a scientific research project titled "Replacing manual argon arc welding for root pass welding with fully automatic argon arc welding technology" and set up a research group. A research team consisting of the company's welding technical experts and chief welding technicians was formed to conduct feasibility studies.
After half a year of technical research and hundreds of tests, the company has finally mastered the process parameters for welding X70 grade steel pipelines. It has completed mechanical and physical property tests in qualified domestic laboratories and successfully passed the review by an expert panel organized by China PipeNetwork. This technology is named "Fully Automatic External Root Argon Arc Welding Technology".
In October 2021, this technology was successfully applied for the first time in the Guangxi Branch Trunk Line Project of Xinjiang Coal-to-Gas Transmission Pipeline with a pipe diameter of 813 millimeters and X70 steel grade. It completed the welding work of a 4-kilometer pipeline, achieving a one-time welding qualification rate of 96%. The welding efficiency was three times that of combined automatic welding, earning high recognition from the project owner.
The company's new technology has attracted widespread attention across the industry. In July this year, the company was invited to participate in the 3rd Oil & Gas Storage and Transportation Pipeline Engineering Welding Technology Forum held alongside the China (Nanjing) International Pipeline Exhibition. Its report entitled Research on Automatic TIG Welding Technology for X70 Steel Long-Distance Transmission Pipelines generated a huge response among domestic pipeline construction and design institutions.
Since then, the company has further applied this technology to large-diameter, X80 high-grade steel pipelines. Relying on multiple ongoing national key projects including the East Trunk Line of Shandong Pipeline Network and Section 4 of the Middle Route (Zaoyang-Xiantao) of the Third West-to-East Gas Transmission Pipeline Project, it has carried out experimental research in complex terrains such as water networks, hilly areas and mountainous regions. Eventually, the company has fully mastered the relevant technologies and passed the expert review organized by the project owner.
During the construction of the East Trunk Line of Shandong Pipeline Network, the company overcame the impacts of extreme weather such as heavy rains and high temperatures. It took 20 days to pass the 100-weld joint running-in assessment using this technology, with a one-time welding qualification rate as high as 98%. This marks the increasingly mature fully automatic external root argon arc welding technology of the company and fills the domestic gap in this welding process.
The breakthrough of this technology is of great significance to the construction of large-diameter and high-grade steel pipelines in China. It indicates that the fully automatic external root argon welding technology can be fully applied to the construction of long-distance transmission pipelines of X70 and X80 steel grades, and it plays a positive role in improving the domestic level of fully automatic welding and constructing national energy pipelines with high quality.
