Patent ID: 8328957

Claim:
An electric resistance welded steel pipe with excellent weld toughness for a line pipe, wherein said steel pipe comprises on a percent by mass basis, 0.01% to 0.15% C, 0.005% to 0.9% Si, 0.2% to 2.0% Mn, 0.01% or less P, 0.01% or less S, 0.1% or less Al, and the balance being substantially Fe and wherein the area fraction of minute defects each having a maximum length of less than 50 μm in a projection plane of an electric resistance welded seam is in the range of 0.000006 to 0.026, a V notch is formed on the electric resistance welded seam of a specimen for an impact test for metallic materials (V-notch Charpy test specimen) according to ISO/DIS 148-1 (JIS Z 2202), and the absorbed energy at −40° C. of the specimen measured by a method for impact test for metallic materials according to ISO 148 (JIS Z 2242) is 315 J or more.