X80 large-diameter thick-wall longitudinal submerged arc welding pipe applicable to low temperature and manufacturing method thereof

Abstract

The invention discloses an X80 large-diameter thick-wall longitudinal submerged arc welding pipe applicable to the low temperature and a manufacturing method thereof. A parent material of the weldingpipe comprises, by mass percentage, 0.04-0.08% of C, 0.15-0.30% of Si, 1.60-1.85% of Mn, less than or equal to 0.004% of S, less than or equal to 0.010% of P, 0.15-0.30% of Ni, 0-0.30% of Cr, 0.1-0.3%of Cu, 0.05-0.10% of Nb, 0.005-0.04% of V, 0.015-0.03% of Ti, 0.10-0.35% of Mo, 0.02-0.05% of Al, less than or equal to 0.008% of N and 0.0003-0.0005% of B. The manufacturing method comprises the steps of preparing a hot rolled steel plate according to the mass percentages of the chemical compositions; and conducting ultrasonic inspection, edge milling, pre-flanging, JCO formation, prewelding, inner welding, outer welding, welding seam X-ray inspection, steel pipe expanding, hydrostatic testing, welding seam ultrasonic testing, pipe end X-ray inspection, chamfering, pipe end magnetic particletesting and appearance quality inspection on the steel plate. A welding joint of the welding pipe is good in low-temperature toughness; and on the premise that heat treatment is not conducted on thewelding pipe after pipe manufacturing, the welding pipe can be directly used at the temperature of minus 45 DEG C or even lower.

Description

Technical field: [0001] The invention relates to a straight seam submerged arc welded pipe and a manufacturing method thereof, in particular to an X80 large-diameter thick-walled straight seam submerged arc welded pipe suitable for low temperature and a manufacturing method thereof. Background technique: [0002] With the continuous development of oil and natural gas exploration to the alpine and permafrost regions and the continuous pursuit of pipeline transportation efficiency and economy, the demand for large-diameter, low-temperature submerged arc welded pipes is increasing. my country is a country with a complex natural environment. When the oil and gas pipeline passes through some alpine regions in the northeast and northwest of my country, the temperature in winter is relatively low. The minimum metal design temperature is -45°C. Under the premise of not adopting heat preservation and heat tracing measures, the current submerged arc welded pipes cannot meet the needs o...

AI Technical Summary

Problems solved by technology

In addition, there is no reference at home and abroad to the X80 steel grade, which is suitable for low-temperature environments and has excellent low-temperature toughness, with a pipe diameter of 1422 mm and a wall thickness > 30 mm.

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