N80 oil casing pipe

What is N80?

N80 is a medium carbon alloy steel in the API 5CT standard, which is widely used in the oil and gas industry, especially in key parts such as oil well casing and tubing. N80 oil casing pipe and N80 seamless steel pipe are important equipment for oil drilling. Its main equipment also includes drill pipe, core pipe and casing, drill pipe and small diameter drilling steel pipe, etc. N80 oil steel pipe is a brand of important equipment for oil drilling, and its main equipment also includes drill pipe, core pipe and casing, drill collar and small diameter drilling steel pipe, etc. The meaning of N80 is the steel pipe grade divided according to the strength of the steel itself. Other steel grades include J55, K55, N80, L80, C90, T95, P110, Q125, V150, etc. N80 oil casing pipe and N80 seamless steel pipe are mainly used for oil well drilling, used to support the well wall during drilling and after completion, to ensure the normal operation of the entire well during drilling and after completion. This article will elaborate on the chemical composition, mechanical properties, corrosion resistance and heat treatment process of N80 casing, and explore its important role in oil drilling.

According to the SY/T6194-96 "Petroleum Casing" standard, the types and packaging of N80 petroleum casing  pipe and N80 seamless steel pipe can be divided into two types: short threaded casing and its coupling and long threaded casing and its coupling. According to SY/T6194-96, domestic casing should be tied with steel wire or steel belt. The exposed part of each casing and coupling thread should be tightened with a protective ring to protect the thread. N80 oil casing pipe and N80 seamless steel pipe are specified in sy/t6194-96, and the casing and its backing are the same type of steel. The sulfur content is <0.045%, and the phosphorus content is <0.045%. The API standard specifies three lengths of N80 oil casing pipe and N80 seamless steel pipe: R1 is 4.88~7.62m, R2 is 7.62~10.36m, and R3 is 10.36m and above.

What are the chemical components of N80 casing?

The chemical composition of N80 casing pipe includes elements such as carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr) and nickel (Ni). Among them, the carbon content ranges from 0.34-0.38%, the silicon content ranges from 0.20-0.35%, and the manganese content ranges from 1.45-1.70%. The precise ratio of these elements gives N80 casing pipe good strength and corrosion resistance.

Carbon (C): 0.34-0.38%

Silicon (Si): 0.20-0.35%

Manganese (Mn): 1.45-1.70%

Phosphorus (P): ≤0.045%

Sulfur (S): ≤0.045%

Chromium (Cr): 0.15-0.25%

Nickel (Ni): 0.25-0.50%

Through strict control of these chemical compositions, N80 casing pipe can not only meet the strength requirements, but also has excellent corrosion resistance, enabling it to adapt to the harsh working conditions in the oil and gas environment.

Mechanical properties of N80 casing pipe

N80 casing pipe has excellent mechanical properties, which are manifested in high yield strength and tensile strength. Its yield strength is not less than 552MPa (80ksi), and its tensile strength is not less than 758MPa (110ksi). In addition, N80 casing pipe also has good toughness and fatigue resistance, suitable for long-term use in harsh environments.

Yield strength: ≥552MPa (80ksi)

Tensile strength: ≥758MPa (110ksi)

Elongation: ≥12%

Hardness: ≤241HB

These performance parameters enable N80 casing pipe to maintain stable performance in high pressure and high stress environments, and it is not easy to suffer fatigue damage during long-term use.

Corrosion resistance of N80 casing pipe

N80 casing pipe has good corrosion resistance and can resist a certain degree of corrosion from acidic and alkaline media. This allows N80 casing pipe to operate stably for a long time in environments such as oil well casing and tubing. The corrosion resistance of N80 casing pipe is mainly due to the chromium and nickel elements in the chemical composition, which can form a dense oxide protective film on the surface of the steel pipe to prevent the invasion of corrosive media.

In practical applications, N80 casing pipe is usually used in corrosive environments containing hydrogen sulfide (H2S) and carbon dioxide (CO2). Its resistance to hydrogen sulfide stress corrosion cracking (SCC) and carbon dioxide corrosion (CO2) are excellent, which can effectively extend the service life of the steel pipe.

Application of N80 casing pipe in oil drilling

N80 casing pipe is widely used in the oil and gas industry, especially in key parts such as oil well casing and tubing. Its main function in oil drilling is to support the well wall, stabilize the well wall during the drilling process and after completion, prevent the well wall from collapsing, and prevent drilling fluid leakage.

N80 casing pipe of different lengths

According to API5CT standard, N80 casing pipe has three lengths to choose from:

R1: 4.88~7.62 meters

R2: 7.62~10.36 meters

R3: 10.36 meters and above

N80 casing pipe of different lengths can be selected according to the drilling depth and specific needs, so that it can be effectively used in different well conditions.

In conclusion

As a medium carbon alloy steel pipe, N80 steel pipe has high strength, excellent corrosion resistance and good heat treatment characteristics. In the oil and gas industry, N80 steel pipe is widely used in key parts such as oil well casing and oil pipe, providing reliable support for oil and gas extraction and transportation. Understanding the chemical composition, mechanical properties and heat treatment characteristics of N80 casing pipe will help to better select and use the steel pipe.