N80 steel pipe is usually casing. N80 casing is an important equipment for oil drilling. Its main equipment includes drill pipe, core pipe and casing, drill collar and small diameter drilling pipe.


Hot-rolled or cold-drawn geological drilling steel sheets are used for domestic casing. The steel strip "Geology" (DZ) is called DZ40, DZ55 and DZ753 commonly used casing steel.
(1) Main importing countries of casing: Germany, Japan, Romania, Czech Republic, Italy, Britain, Austria, Switzerland, the United States, Argentina and Singapore also have imports. Import API 5A, 5AX, 5AC standard reference. Steel grades are H-40, J-55, N-80, P-110, C-75, C-95, etc. Main specifications 139.77.72R2, 177.89.19R-2, 244.58.94R-2, 244.510.03R-2, 244.511.05R-2.


(2) The length of API is 3:R-1 is 4.88-7.62 m, R-2 is 7.62-10.36 m and R-3 is more than 10.36 M.


(3) Some imported goods are marked LTC, i.e. long threaded fastened casing.


(4) For example, Nippon Railway, Sumitomo, Kawasaki, etc., steel number NC-55E, NC-80E, NC-L80, NC-80E, NC-80HE, etc.


(5) In the case of claim, appearance defects such as black buckle, thread damage, pipeline folding, broken buckle and tight tolerance of thread, coupling J value defect, brittle fracture of casing and quality problems of low yield strength appeared.