Abstract: A steel pipe collapse strength prediction model generation method, a steel pipe collapse strength prediction method, a steel pipe manufacturing characteristics determination method, and a steel pipe manufacturing method capable of highly accurately predicting the collapse strength under external pressure bending of a coated steel pipe coated after steel pipe forming in consideration of the pipe-making strain during steel pipe forming and coating conditions as well as the bending strain during construction.

Abstract: 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.

Abstract: A steel pipe collapse strength prediction model generation method, a steel pipe collapse strength prediction method, a steel pipe manufacturing characteristics determination method, and a steel pipe manufacturing method capable of highly accurately predicting the collapse strength of a steel pipe after forming or a coated steel pipe in consideration of the pipe-making strain during forming. Into a steel pipe collapse strength prediction model generated by the prediction model generation method, steel pipe manufacturing characteristics including the shape of a steel pipe to be predicted after forming, strength characteristics, and the pipe-making strain are input to predict the collapse strength after forming.

Abstract: Provided is a method for evaluating brittle crack arrestability of a steel plate by using a large test piece, in which a notch is disposed on one edge in a central portion, in which an embrittled region having a predetermined length L is formed at a tip of the notch or formed so as to include the tip, and in which a fusion zone spaced from the embrittled region is disposed. The fusion zone is formed on one side or both sides of the embrittled region at a distance d from the embrittled region, where d is determined in relation to a thickness t of the steel plate, and a length of the fusion zone is determined by adding ?L1 (0.3L to ?0.3L) to a length L of the embrittled region and by subtracting ?L2 (0 to 0.4L) from the length L.

Abstract: 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.

Abstract: Provided is a method for evaluating brittle crack arrestability of a steel plate by using a large test piece, in which a notch is disposed on one edge in a central portion, in which an embrittled region having a predetermined length L is formed at a tip of the notch or formed so as to include the tip, and in which a fusion zone spaced from the embrittled region is disposed. The fusion zone is formed on one side or both sides of the embrittled region at a distance d from the embrittled region, where d is determined in relation to a thickness t of the steel plate, and a length of the fusion zone is determined by adding ?L1 (0.3L to ?0.3L) to a length L of the embrittled region and by subtracting ?L2 (0 to 0.4L) from the length L.