To provide a method for manufacturing a steel pipe superior in hydrogen-induced cracking resistance, which is usable for a line pipe having high reliability even when transporting crude oil and a natural gas in cold districts and under a damp environment containing hydrogen sulfide and carbon dioxide.
The method for manufacturing the steel pipe superior in hydrogen-induced cracking resistance satisfies expression (1): x/a+y/b+z/c≤1, wherein x is the maximum Vickers hardness of a base metal used for manufacturing the steel pipe, including a central segregated portion; z (mm) is the maximum particle size of non-metallic inclusions contained in the base metal; y (%) is bending strain when the base metal for manufacturing the steel pipe is bent; and a, b and c are constants according to a standard of the steel pipe, and a=400, b=20 and c=0.4 according to API5LX65.
Yoshiaki Naito
Cui Shu Tetsu
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