A long steel pipe for reel-lay installation formed of electric resistance welded (ERW) steel pipes and having high buckling resistance and a method for producing the long steel pipe for reel-lay installation are provided. The long steel pipe is formed by successively butt-joining longitudinal ends of the ERW steel pipes by girth welding so that girth welds are formed. The ERW steel pipes are successively butt-joined in the pipe longitudinal direction such that the 0 o'clock cross-sectional position or the 6 o'clock cross-sectional position of one of adjacent ERW steel pipes faces an area from the 2 o'clock cross-sectional position to the 4 o'clock cross-sectional position or an area from the 8 o'clock cross-sectional position to the 10 o'clock cross-sectional position of the other of the adjacent ERW steel pipes. Accordingly, even when the long steel pipe is spooled onto a reel for reel-lay installation such that the 0 o'clock cross-sectional position (seam) or the 6 o'clock cross-sectional position thereof, at which the long steel pipe has high-yield-ratio low-uniform-elongation tensile characteristics, is at the reel inner side (intrados) or the reel outer side (extrados), large axial strains that cause local buckling or fracture are not generated. Thus, a long steel pipe for reel-lay installation with high buckling resistance and a low risk of buckling or fracture and a method for producing the long steel pipe for reel-lay installation are provided.
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