Abstract: A clad steel pipe excellent in corrosion resistance and low-temperature toughness, which comprises a cladding sheet of high corrosion resistant steel and a substrate sheet of low-alloy high-strength steel, the substrate sheet consisting, as the fundamental constituents, essentially of:carbon: from 0.002 to 0.050 wt. %,silicon: from 0.05 to 0.80 wt. %,manganese: from 0.80 to 2.20 wt. %,niobium: from 0.01 to 0.10 wt. %,aluminum: from 0.01 to 0.08 wt. %,nitrogen: from 0.002 to 0.008 wt. %, and,the balance being iron and incidental impurities;or, the substrate sheet further additionally containing, as the strength-improving constituents, at least one element selected from the group consisting of:copper: from 0.05 to 1.00 wt. %,nickel: from 0.05 to 3.00 wt. %,chromium: from 0.05 to 1.00 wt. %,molybdenum: from 0.03 to 0.80 wt. %,vanadium: from 0.01 to 0.10 wt. %, and,boron: from 0.0003 to 0.0030 wt.

Abstract: For producing steel pipe from thick steel plate, an up-set shrinker is employed for reducing and processing an O-shaped pipe-blank in a facility for producing thick wall steel pipe. The up-set shrinker is provided with a plurality of reducing shrinker dies located around the pipe-blank in correspondence to parts other than abutting parts of the edges of the pipe-blank, and with at least one edge processing shrinker die located in correspondence to the butting parts of the edges of the pipe-blank. The edge processing shrinker die is formed at its die surface with a projecting portion over the length of the die. The edge processing shrinker die is actuated independently of the reducing shrinker dies.