Method for manufacturing high-strength X90 steel grade spiral submerged arc welded pipe

Abstract

The invention discloses a method for manufacturing a high-strength X90 steel grade spiral submerged arc welded pipe. The method comprises the following steps of: uncoiling; leveling; edge milling; pre-springing; forming; inside welding; outside welding; pipe end diameter expansion; layering and ultrasonic examination of a base material; X-ray examination of a welding seam; hydrostatic test; ultrasonic examination of the welding seam; and pipe end chamfering. By increasing the processes of double edge milling, edge pre-springing and pipe end diameter expansion in the processing steps, the manufacturing method successfully solves the technical problems of poor forming stability, the difficulty for the performance of the welded joint to meet the technical requirement and the like during the manufacturing of the high-strength X90 steel grade spiral submerged arc welded pipe.

Description

technical field [0001] The invention relates to a manufacturing technology of a spiral seam submerged arc welded pipe, in particular to a manufacturing method of a high-strength X90 steel grade spiral seam submerged arc welded pipe. Background technique [0002] The spiral seam submerged arc welded pipe is made by spirally bending steel coils according to a certain radius of curvature and then welding them together along the gap between the butt joints of the steel plates. Because spiral seam submerged arc welded pipe has the advantages of low investment and various production varieties, it has become the most widely used steel pipe manufacturing method in China. However, due to the limitations of its forming method and the relatively low strength of steel pipes for a long time, there are few productions of high-strength steel pipes. At present, the steel used in the steel pipe produced by the spiral seam submerged arc welded pipe does not exceed the X80 steel grade. [00...

AI Technical Summary

Problems solved by technology

The current production method still has many problems in the production of high-strength spiral submerged arc welded pipes. The main manifestations are: as the strength of the steel increases, the deformation of the steel strip in the former, especially the edge of the strip on the delivery side, is insufficient. At the same time, the edge trimming process commonly used at present will also cause the under-flange phenomenon of the plate edge. If it is not corrected in the subsequent process, pouting, tightness inside the forming seam and looseness outside the forming seam, wrong edge, etc. will easily occur during the production process. Defects can even cause fatal defects such as weld micro-cracks; problems such as crescent bends in the coil itself significantly affect the forming stability of the steel pipe, making the circumference and ellipticity of the steel pipe change greatly, and the shape of the steel pipe cannot be effectively guaranteed. Dimensional stability has a certain impact on the on-site butt joint construction of steel pipes; in addition, as the strength of steel increases, the welding process becomes more difficult. How to control the structure and performance of welded joints is also a key problem that needs to be solved

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