Abstract: Along with the quick development of the domestic petroleum industry,the annual demand for oil casings is getting bigger and bigger,while requirements for performance of such pipes have been more stringent.Elaborated here in the assay are the main aspects of the HFW casing in the N80 non-quenched and tempered steel as developed by CNOOC Kingland Pipeline Co.,Ltd.,covering design of the chemical composition,the metallo-graphic structure,the manufacturing flow,the key techniques and critical control points,and the product performance,etc.Relevant inspection and test results show that the said HFW casing is up to the requirements as specified in API Spec.5CT,and in possession of rather high impact toughness as well as weld seam non-sensitivity to groove corrosion.