N80 oil casing pipe is an important equipment for oil drilling. Its main equipment also includes drill pipe, core pipe and casing, drill collar and steel pipe for small diameter drilling. The domestic casing is made of geological drilling steel by hot rolling or cold drawing. The steel number is represented by "geology" (DZ). The commonly used casing steel grades are DZ40, DZ55 and DZ753.

(1) The main importing countries of oil casings are: Germany, Japan, Romania, Czech Republic, Italy, Britain, Austria, Switzerland, the United States, and Argentina and Singapore.
(2) The API has three lengths: R-1 is 4.88~7.62m, R-2 is 7.62~10.36m, and R-3 is 10.36m to longer.
(3) Some imported goods are marked with the word LTC, that is, the filament buckle casing.
(4) In addition to adopting API standards, there are a small number of Japanese factory standards imported from Japan.
(5) In the case of claim, there have been black buckles, thread damage, tube folding, broken buckles and thread tight distance tolerance, coupling J value is poor and other appearance defects and casing cracking, low yield strength, etc. quality problem.

Uses: It is mainly used for oil well drilling mainly for supporting the well wall during and after drilling to ensure the drilling process and the normal operation of the entire well after completion.

Type: Oil casing pipe type and packaging According to SY/T6194-96 "oil casing" short threaded casing and its coupling and long threaded casing and its coupling. According to SY/T6194-96, domestic casings should be bundled with steel wire or steel belt. The exposed portion of each bushing and coupling thread should be screwed with a guard ring to protect the threads.

Specifications: Domestic casing according to SY/T6194-96 regulations, the length of the casing is not fixed, its range is 8-13m. But not less than 6m of casing can be provided, the number must not exceed over 20%.

Appearance: The inner and outer surfaces of the casing shall be free from folding, hairline, separation, cracks, rolling and crusting. These defects should be completely removed and the depth of removal should not exceed 12.5% ​​of the nominal wall thickness.

Quality requirements: The surface of the casing and coupling threads should be smooth and free of burrs, tears, and other defects sufficient to cause thread breakage to affect strength and tight joints.

Packing:
According to SY/T6194-96, domestic casings should be bundled with steel wire or steel belt. The exposed portion of each bushing and coupling thread should be screwed onto the guard ring to protect the threads.

Chemical composition test:
(1) According to SY/T6194-96. The casing and its couplings are of the same steel grade. The sulfur content is <0.045%, and the phosphorus content is <0.045%.
(2) Take chemical analysis samples according to the provisions of GB222-84. Chemical analysis was carried out in accordance with the relevant provisions of GB223.
(3) The first edition of the American Petroleum Institute ARISPEC5CT1988. Chemical analysis according to the latest version of ASTM E59, chemical analysis according to the latest version of ASTM E350 Analysis.

Oil casing calculation formula:
(outer diameter - wall thickness) * wall thickness * 0.02466 = kg / m (weight per meter)

Other:
According to the American Petroleum Institute standard APISPEC5CT 1988 first edition, casing steel grades H-40, J-55, K-55, N-80, C-75, L-80, C-90, C-95, P- 110, Q-125 a total of 10 kinds.

The bushings shall be supplied with threads and couplings or in the form of any of the following pipe ends:
Flat end, round thread without coupling or with coupling, partial trapezoidal thread with or without coupling, straight-through thread, special end machining, sealing ring structure.