Patent ID: 8147623

Claim:
A seamless steel pipe as a fuel injection pipe, consisting essentially of: by mass, C: 0.12 to 0.27%, Si: 0.05 to 0.40%, and Mn: 0.8 to 2.0%, and the balance being Fe and impurities, the contents of Ca, P, and S in the impurities being Ca: 0.001% or less, P: 0.02% or less, and S: 0.01% or less, respectively, wherein the steel pipe has a tensile strength of 500 N/mm 2 or higher and the microstructure of the steel pipe comprises bainite and ferrite; and wherein the maximum diameter of nonmetallic inclusions present in at least in a region extending from the inner surface of the steel pipe to a depth of 20 μm is 20 μm or less.