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: A method of evaluating deformability of steel pipe with which deformability can be evaluated regardless of whether the pitch of pipe expansion is coarse or fine, and a method of manufacturing steel pipe using the method of evaluating deformability, are disclosed. A method of evaluating deformability of steel pipe according to the present invention is a method for evaluating deformability of a steel pipe manufactured through a pipe expanding step performed using a die. The method of evaluating deformability of steel pipe includes an outer shape acquiring step of measuring a shape of the steel pipe to acquire an outer shape, a power spectrum acquiring step of acquiring a power spectrum from a wavy shape of the acquired outer shape, and a determining step of integrating the acquired power spectrum for a predetermined wavelength range and determining deformability on the basis of the resulting integral.

Abstract: In a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process, a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively. A method of manufacturing a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process includes a step of forming the waveform shape such that a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively.

Abstract: In a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process, a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively. A method of manufacturing a steel pipe having a waveform shape formed on an outer diameter thereof by a pipe expansion process includes a step of forming the waveform shape such that a value a/w is 0.038% or less, where a and w denote an amplitude and a wavelength of the waveform shape, respectively.

Abstract: A UOE steel pipe used to form a structure by performing butt circumferential welding and having an outside diameter shape in a waveform in a longitudinal direction is shaped to have no local minimum of the outside diameter shape in the waveform within a predetermined length from both longitudinal end portions.

Abstract: A UOE steel pipe used to form a structure by performing butt circumferential welding and having an outside diameter shape in a waveform in a longitudinal direction is shaped to have no local minimum of the outside diameter shape in the waveform within a predetermined length from both longitudinal end portions.