API 5CT Grade N80 Type Q Casing Steel Pipes

API 5CT N80-Q casing pipe is a widely applied medium-grade steel casing in oil and gas well construction. Falling between lower-grade products such as J55/K55 and higher-performance grades like L80 or P110, N80 offers a balance of mechanical strength, toughness, and economic efficiency. Within the N80 specification, there are two distinct levels: N80 Type 1 and N80 Type Q, with the latter recognized for its improved quenching and tempering process that enhances collapse resistance and downhole performance.

In addition to standard N80 grades, materials such as 9Cr-80 and 13Cr-80 are available for wells where corrosive environments (e.g., CO₂, H₂S, or high chloride brines) demand extra resistance. With yield strengths typically around 552–689 MPa and tensile strengths exceeding 689 MPa, API 5CT N80-Q casing is trusted for medium-depth oil and gas wells, providing structural integrity and zonal isolation under demanding geological conditions.

API 5CT N80 casing manufacturing processes

Like other grades of API 5CT, manufacturing processes includes hot rolled in seamless and ERW welded. In most of the cases the casing pipe adopts the seamless type.

Connection type, ends and Couplings

N80 casing pipe connection type usually refer to BTC, which is buttress thread marked with BC symbol; Other than this type there are short round and long round thread types, corresponding marked as SC or LC symbol. Octal also specialized in supplying premium connections in different types, air proof casing connections. And in case client required, we could customize connection threads and couplings.

N80-1 and N80 Q casing pipe sizes

Casing pipe sizes of N80-1 and N80-Q refer to the pipe diameters equal to or more than 5 1/2” inch. Blow to this size is the tubing.

Chemicals and mechanical strength

For grade N80 type Q the chemicals composition details as: Unit in %, C content 0.28-0.32 (OD above 9 5/8” 244.48 mm, C content is 0.22-0.29), Si content 0.17-0.37, Mn content 1.30-1.45 (OD above 9 5/8” 244.48 mm, Mn content is 1.3-1.60, maximum Cr 0.25, maximum Ni 0.20, maximum Cu 0.20, V 0.07-0.12, maximum P 0.025, maximum S 0.020.
For N80 type 1 is the same chemicals with type Q.
Yield strength for N80 type Q and type 1, is 552 Mpa to 758 Mpa. Tensile strength minimum shall be 689 Mpa.

API 5CT N80 Casing pipe manufacturer and supply range

Standards: API SPEC 5CT casing steel pipe
Grades: N80 type 1, N80 type Q, L80, 9Cr-80, 13Cr-80
Stock Available: Yes
Manufacturing process: Seamless, ERW
Outer Diameter: 5 1/2”, 6 5/8”, 7”, 7 5/8”, 7 3/4”, 8 5/8”, 9 5/8”, 10 3/4”, 11 3/4”, 13 3/8”, 16”, 18 5/8”, 20”
Thickness: 14 LB/FT to 106.59 LB/FT, 0.244” to 0.875”
Coupling thread: BTC, LTC, Buttress (Regular, Special bevel or special clearance), premium connections threads.
Length: R2, R3, customized

conclusion

In modern well drilling projects, selecting the right casing grade is essential to maintaining wellbore integrity and production reliability. API 5CT N80-Q casing pipe provides a proven solution for medium-depth wells, balancing mechanical strength, collapse resistance, and cost-effectiveness. With options such as N80 Type 1, N80-Q, 9Cr-80, and 13Cr-80, operators can match the casing grade precisely to the reservoir environment and drilling program.

As a global supplier, Octal Steel delivers fully certified API 5CT N80-Q casing pipes, complete with mill test certificates (MTC), traceability, and strict compliance with API 5CT standards. Through rigorous quality control and extensive industry expertise, Octal Steel ensures that every casing string contributes to safe drilling operations and long-term well performance. For oil and gas companies seeking reliable tubular solutions, Octal Steel provides both technical precision and trusted supply capability.