Bimetal Composite Welded Pipe Manufacturing Process

Abstract

The invention discloses a bi-metal composite welding pipe manufacturing technology. The bi-metal composite welding pipe manufacturing technology comprises the following steps of (1) discharging, (2) bending molding, (3) welding, (4) heat treating and (5) reducing and circle rectifying. According to the bi-metal composite welding pipe manufacturing technology, through precise discharging and the equidistant and small-step multiple molding mode, the geometrical shape of the radial cross section of a finally-molded pipe blank is a circle with the consistent curvature; and after an upper mold anda lower mold which are matched with the pipe diameter are closed to conduct reducing and circle rectifying on the oval pipe blank, the mold is simple, the equipment cost is low, operation is convenient, and the circular degree, the strength and the corrosion resistance of a steel pipe can be guaranteed.

Description

technical field [0001] The invention relates to a bimetal composite welded pipe manufacturing process, in particular to a bimetal composite welded pipe manufacturing process for oil pipelines. Background technique [0002] Pipelines used in petroleum, chemical and other fields have both anti-corrosion and strength requirements. Now bimetallic composite pipes are usually used. The inner layer is mostly austenitic stainless steel or nickel-based alloy, and the outer layer is often made of carbon steel; Composite pipes usually use mechanical expansion to expand the diameter of the entire length in sections to achieve the correction of the ellipticity of the welded pipe. It needs to heat the outer pipe to 500-900°C, and then place the expanded mandrel in the inner pipe along the axial direction. Move, expand the diameter of the inner pipe, and then cool it to make the inner and outer pipes fit together. Due to the change of the axial size of the pipe fittings, the end structure ...

AI Technical Summary

Problems solved by technology

[0002] Pipelines used in petroleum, chemical and other fields have both anti-corrosion and strength requirements. Now bimetallic composite pipes are usually used. The inner layer is mostly austenitic stainless steel or nickel-based alloy, and the outer layer is often made of carbon steel; Composite pipes usually use mechanical expansion to expand the diameter of the entire length in sections to achieve the correction of the ellipticity of the welded pipe. It needs to heat the outer pipe to 500-900°C, and then place the expanded mandrel in the inner pipe along the axial direction. Move, expand the diameter of the inner pipe, and then cool it to make the inner and outer pipes fit together. Due to the change of the axial size of the pipe fittings, the end structure is irregular, and follow-up processing such as head cutting is required; the main disadvantages of this process are: : The mechanical damage to the inner surface of the inner pipe during diameter expansion is relatively large, and its tensile deformation may enlarge the defects of this type of raw material, affecting its strength and corrosion resistance, and the large diameter expansion machine has a complex structure and high equipment cost; Heating the outer tube, high energy consumption and high manufacturing cost

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