In modern society, line pipe is belong to low or ultra low carbon steel pipe with micro-alloyed. Line pipe is a type of high tech and high value added products which is all applied in the areas of metallurgy technology nearly 20 years of new achievements. The development trend of pipeline project is applying large diameter, high pressure, high cold and corrosive, thick wall line pipe. Therefore, in modern society, line pipe should have a high strength, low bauschinger effect, high toughness and resistance, brittle fracture, low carbon volume and good weldability properties. Meanwhile, line pipe has high resistance to HIC and anti-H2S corrosion features is necessary. The optimized production strategies is to improve the steel cleanliness and organizations uniformity, C≤0.09%, S≤0.005%, P≤0.01%, O≤0.002%, and to take micro-alloying, vacuum degassing + CaSi, the continuous casting process under light pressure, multi-stage thermomechanical rolling and accelerated cooling versatile batch process. Domestic and international pipeline specification does pipelines toughness index of steel, pipe only to specific requirements:

(1) Minimum temperature (-5 ℃) DWTT≥85% SA;
(2) the lowest temperature (-5 ℃) Charpy impact energy ≥145J.

Pipeline Technical conditions commonly used by the American Petroleum Institute standards APISpec5L, but the domestic user's specific projects or specific orders and technical conditions are often much more stringent than the API standard.

Smelting technology with more stringent requirements, technical difficulties focused on:

1) content of impurity elements control;
2) inclusion control;
3) a narrow composition control.