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.