From the comprehensive evaluation of the development trend of oil and gas pipelines, pipeline laying conditions, main failure modes and failure causes, pipeline steel should have good mechanical properties (thick wall, high strength, high toughness, wear resistance), and should also have large diameter, weldability, resistance to severe cold and low temperature, corrosion resistance, resistance to sea water, etc..
1. High strength: pipeline steel not only requires high tensile strength and yield strength values, but also requires a yield ratio in the range of 0.85 to 0.93.
2. High impact toughness: high impact toughness can meet the requirements of preventing cracking.
3. Low ductile-brittle transition temperature: severe geographic and climatic conditions require pipeline steel to have a sufficiently low ductile-brittle transition temperature. The shear area of DWTT (drop weight tear test) has become the main control index to prevent brittle failure of pipelines. The general specification requires that the shear area of the sample fracture is more than 85% at the lowest operating temperature.
4. Pipeline steel should have excellent resistance to hydrogen induced cracking (HIC) and resistance to sulfide stress corrosion cracking (SSCC).
5. Good welding performance: good weldability of pipeline steel is essential to ensure the integrity and welding quality of the pipeline.
