High-strength drag reduction type spiral steel pipe for long-distance oil and gas transportation and machining process thereof

Abstract

The invention discloses a high-strength drag reduction type spiral steel pipe for long-distance oil and gas transportation. The base metal steel plate comprises, by weight, 0.12%-0.2% of C, 0.25%-0.31% of Si, 1.09%-1.14% of Mn, 0.15%-0.2% of P, 0.09%-0.12% of S, 0.015%-0.024% of V, 0.04%-0.06% of Cr, 0.005%-0.013% of Ni, 0.015%-0.022% of Cu and the balance Fe, and the thickness of the steel plateranges from 8.5 mm to 9.5 mm; the welding seam comprises, by weight, 0.05%-0.08% of C, 0.12%-0.16% of Si, 5.3%-5.8% of Mn, smaller than or equal to 0.15% of P, smaller than or equal to 0.06% of S, 0.044%-0.052% of V, 0.02%-0.06% of Cr, 0.22%-0.28% of Ni, 0.09%-0.015% of Cu, 0.02%-0.027% of Ti, 0.02%-0.08% of B and the balance Fe; the process comprises the steps of uncoiling, flattening, edge milling, pre-bending, rolling sleeve forming, rust removing, oil removing, inner welding, outer welding and pipe end diameter expanding; double-wire serial submerged arc automatic welding is adopted for inner welding, the first wire is subjected to direct current, the current is 985-1035A, the voltage is 31-33V, the second wire is subjected to alternating current, the current I is equal to 445-525 A, the voltage is 34-36 V, the distance between welding wires is 10-14 mm, and the speed is 1.6-1.7 m / min; and double-wire serial submerged arc automatic welding is adopted for outer welding, the first wire is subjected to direct current, the current is 895-940 A, the voltage is 31-33 V, the second wire is subjected to alternating current, the current is 445-480 A, the voltage is 34-36 V, the distancebetween welding wires is 12-16 mm, and the speed is 1.6-1.7 m / min. The spiral steel pipe is few in weld pores, good in mechanical property and suitable for long-distance oil and gas transmission.

Description

technical field [0001] The invention relates to the technical field of spiral steel pipes, in particular to a high-strength drag-reducing spiral steel pipe for long-distance oil and gas transportation and its processing technology. Background technique [0002] Oil and gas pipeline transportation is the most suitable transportation method for long-distance transportation of oil and gas. The pipelines used usually include straight seam steel pipes and spiral steel pipes. Compared with straight seam steel pipes, spiral steel pipes have more prominent advantages in pipeline crack arrest and are more widely used in oil and gas pipeline transportation. [0003] The existing Chinese patent whose authorized announcement number is CN102284550B can be referred to, which discloses a manufacturing process of spiral seam submerged arc welded pipe, including: 1) raw material inspection, 2) material preparation, 3) uncoiling, 4) leveling, 5) Steel strip butt-to-end, 6) Disc cutting, 7) E...

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Problems solved by technology

[0005] The weld performance of the spiral steel pipe has an important influence on the mechanical properties such as the overall strength of the spiral steel pipe. However, during the welding process of the spiral steel pipe, pores are prone to appear in the weld, which will directly affect the mechanical properties of the weld, and then lead to spiral The overall service performance of steel pipes has declined severely, affecting the safety and stability of oil and gas transportation

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