Reducing production method of deepwater submerged arc welding large-caliber steel pipes

Abstract

The invention discloses a reducing production method of deepwater submerged arc welding large-caliber steel pipes. In order to overcome the defects of reduction of the compression strength and incapability of satisfying the bruising pressure performance requirements of deepwater pipelines in a traditional JCOE process for producing thick-wall steel pipes, the method comprises such process steps as edge milling, edge pre-bending, JCO molding, joint closing and prewelding, inner welding, outer welding, mechanical reducing, quality checking, water pressure test, quality checking and chamfering, wherein the mechanical reducing is to perform the annular compression for the whole lengths of the steel pipes by a steel pipe sizing press. The method has the following beneficial effects: the steel pipe sizing press is used for annularly compressing the full lengths of the steel pipes, so that the steel pipes are locally deformed, the diameters of the pipes are decreased, and the size tolerances of the steel pipes are improved; because of the mechanical reducing, the residual stress is reduced, the straightness of the steel pipes is improved, the cold molding process of the steel pipes is optimized, and the compression yield strength and the bruising pressure of the steel pipes are improved; and all technical parameters of the steel pipes accord with the deepwater pipeline requirements through strict technical control.

Description

technical field [0001] The invention relates to a method for manufacturing large-diameter steel pipes by submerged arc welding, in particular to a method for manufacturing large-diameter steel pipes by submerged arc welding for deep water. Background technique [0002] The deep-sea oil and gas fields currently developed are generally in waters with a water depth of 2000-3000m, and the deepest drilling waters and oil production wells have reached a water depth of more than 6000m. It will continue to increase, and will eventually reach about 50% of global natural gas production, which will increase the investment in natural gas infrastructure, and the number of subsea pipelines required in the construction of natural gas infrastructure will increase significantly. [0003] In the past 20 years, JCOE (Large Diameter Longitudinal Double-sided Submerged Arc Welding Steel Pipe Forming Process) has been gradually used in the production of large-wall thick submarine line pipes in ad...

AI Technical Summary

Problems solved by technology

[0006] In order to overcome the shortcomings of the reduction of compressive strength existing in the production of thick-walled steel pipes by the JCOE process and the inability to meet the pressure performance requirements of deep-water pipelines, the invention provides a method for manufacturing large-diameter steel pipes for deep-water submerged arc welding.

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