Method for manufacturing X80-stage phi1422 mm longitudinal submerged arc welding pipe

Abstract

The invention discloses a method for manufacturing an X80-stage pipeline steel longitudinal submerged arc welding pipe. The method is used for manufacturing submerged arc welding pipes special for oil and gas conveying. The method comprises the steps that a hot-rolled steel plate with the microscopic structure being a proeutectoid ferrite+MA+granular bainite polyphase structure is utilized, and after processes of edge milling, pre-bending, JCO molding, pre-welding, finish welding and the like, the large-caliber, thick-wall and large-strain submerged arc welding pipe capable of being used for seismic zones, permafrost regions, landslide zones and other areas with deformation prone to happening is manufactured. The longitudinal submerged arc welding pipe manufactured through the method has the beneficial effects that the good mechanical property is achieved, the overall property of the welding pipe is uniform and stable, the geometric dimension is good, and the use requirements of steel pipes for seismic fracture zones, the permafrost regions and the landslide zones can be met.

Description

technical field [0001] The invention relates to a method for manufacturing a straight seam welded pipe, and is characterized in that it relates to a method for manufacturing an X80 grade Φ1422mm ultra-large diameter, thick wall, and large strain special-purpose straight seam submerged arc welded pipe. Background technique [0002] The new round of trunk natural gas pipeline construction requires the characteristics of long transmission distance, higher pressure and large diameter transmission. There is a trend of large-scale long-distance natural gas pipelines, and high-strength and large-wall-thickness transmission pipes are required. As a mature high-strength pipeline steel, X80 grade pipeline steel can effectively reduce the cost of pipeline construction and have greater economic benefits as a high-pressure, large-input natural gas transmission pipeline. [0003] After long-term and large-scale exploitation, areas that are easy to exploit oil and gas resources have been d...

AI Technical Summary

Problems solved by technology

For large-diameter, thick-wall submerged arc welded pipes with large strain capacity, it is not only necessary to solve the problem that with the continuous increase of pipeline steel wall thickness, the key indicators such as pipe body DWTT performance, low temperature impact toughness, yield ratio and uniform elongation are getting worse. At the same time, it is necessary to make the welded pipe have good longitudinal deformation ability, and ensure that the plasticity and toughness of the welded pipe will not be greatly reduced during the anti-corrosion coating process. Fabrication of seam submerged arc welded pipe poses higher challenges

[0004] At present, domestic research on X80 large-diameter, thick-walled, and large-strain submerged arc welded pipes is mainly focused on the manufacturing method of Ф1422mm pipe diameter conventional longitudinal seam welded pipes or Ф1219mm pipe diameter large strain longitudinal seam welded pipes, but for Ф1422mm pipe diameters , The manufacturing method of large strain longitudinal welded pipe is not involved

For example, the patent application No. 201310147327.7 "Manufacturing Method of Super Large Diameter and Large Wall Thickness Longitudinal Welded Pipe" only involves the manufacturing method of Ф1422mm pipe diameter and large wall thickness longitudinal welded pipe, and does not involve large strain welded pipe; the patent application number is 201010251848.3 "A Manufacturing Method for High-Grade Large-Strain Pipeline Steel and Steel Pipe" only involves the manufacturing method of Ф1219mm pipe diameter and 26.2mm wall thickness large-strain straight seam welded pipe. For Ф1422mm pipe diameter and 30mm wall thickness Seam welded pipe is not involved

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