API 5CT N80 Casing Pipe
API 5CT N80 Casing is a medium-high strength Oil Country Tubular Good (OCTG) belonging to Group 2 of the API standards. Designed for deep wells and complex geological formations, it features a minimum yield strength of 80,000 psi (552 MPa), reaching up to 110,000 psi, and a minimum tensile strength of 100,000 psi (689 MPa).
The N80 grade is divided into two types: N80-1 and N80-Q. While their mechanical properties regarding tensile and yield strength are identical, the core difference lies in the heat treatment process: N80-1 is typically Normalized, whereas N80-Q must undergo Quenching and Tempering (Q&T). This specialized treatment provides N80-Q with superior low-temperature impact toughness and higher reliability in demanding environments.
In practical applications, N80 is commonly used in wells exceeding 3,000 meters, offering significantly higher resistance to collapse pressure and internal yield (burst) pressure than J55 or K55. Visually, N80-1 is identified by one red band, while N80-Q is marked with one red and one green band.
Need precise collapse and burst ratings for N80? Download the Full Technical Datasheet for your engineering files.
API 5CT N80 Casing Pipe Overview
API 5CT N80 casing pipe is a Group 1 OCTG grade for medium depth wells, supplied in two variants: N80-1 (as-rolled or normalized) and N80Q (quenched and tempered). Both deliver identical strength, and both are available from GNEE with API 5CT monogrammed mill certification.
Standard: API Spec 5CT / ISO 11960, Group 1, PSL1 and PSL2
Strength: yield 80,000-110,000 psi (552-758 MPa), min tensile 100,000 psi (689 MPa)
Sizes: OD 4-1/2" to 20", weights 9.5-133 lb/ft, R1/R2/R3 lengths
Connections: STC, LTC, BTC and premium connections on request
Color code: N80-1 one red band; N80Q one red + one bright green band
Service: sweet wells deeper than 3,000 m; NOT for sour service (use L80-1, C90 or T95)
Editor's note: API 5CT does not set mandatory C or Mn ranges for Group 1 grades like N80 - chemistry is at the manufacturer's option, with only P and S capped by PSL level (PSL1: P 0.030% / S 0.030% max; PSL2: P 0.020% / S 0.010% max). The narrow C 0.34-0.38% and Mn 1.45-1.70% figures in the table below are typical mill control ranges. The Heat Treatment row of the mechanical properties table also reads across two columns: "Normalized" applies to N80-1 and "Quenched & Tempered" applies to N80Q.
API 5CT N80 OCTG Pipe Color Band Identification
Used at the rig site for quick identification of the steel grade.
| Grade | Color Band Identification |
| N80-1 | One Red Band |
| N80-Q | One Red Band + One Green Band |
API 5CT N80 Casing Pipe Chemical Composition
|
Grade |
C |
Si |
Mn |
P |
S |
Cr |
Ni |
Cu |
Mo |
|
N80 type 1 / Q |
0.34-0.38 |
0.20-0.35 |
1.45-1.70 |
0.020 |
0.015 |
0.15 |
/ |
/ |
/ |
API 5CT N80 Casing Pipe Mechanical Properties
N80 is a medium-to-high strength steel grade. The "80" indicates a minimum yield strength of 80,000 psi.
| Property | Imperial Unit (psi) | Metric Unit (MPa) |
| Yield Strength | 80,000 - 110,000 | 552 - 758 |
| Min. Tensile Strength | ≥ 100,000 | ≥ 689 |
| Min. Elongation | Calculated per API formula | Calculated per API formula |
| Hardness | Not specified by API | Not specified by API |
| Heat Treatment | Usually Normalized | Quenched & Tempered (Q&T) |
API 5CT N80 oil well Casing Sizes
Due to its higher strength, N80 is commonly used in deeper wellbore sections.
| Outside Diameter (OD) | Nominal Weight | Wall Thickness | Inside Diameter (ID) | Drift Diameter |
| inch (mm) | lb/ft ( kg/m ) | inch (mm) | inch (mm) | inch (mm) |
| 5-1/2" (139.7) | 17.00 (25.30) | 0.304 (7.72) | 4.892 (124.26) | 4.767 (121.08) |
| 20.00 (29.76) | 0.361 (9.17) | 4.778 (121.36) | 4.653 (118.19) | |
| 7" (177.8) | 26.00 (38.69) | 0.362 (9.19) | 6.276 (159.41) | 6.151 (156.24) |
| 29.00 (43.16) | 0.408 (10.36) | 6.184 (157.07) | 6.059 (153.90) | |
| 9-5/8" (244.5) | 40.00 (59.53) | 0.395 (10.03) | 8.835 (224.41) | 8.679 (220.45) |
| 47.00 (69.94) | 0.472 (11.99) | 8.681 (220.50) | 8.525 (216.54) |
API 5CT N80 oilfield Casing Pipe Dimensional Tolerances
Standard tolerances for API 5CT N80 casing are as follows:
| Item | Tolerance Requirement |
| Outside Diameter (D) | For D≥4−1/2": +1.00% / -0.50% |
| Wall Thickness (t) | -12.5% |
| Weight of Single Length | +6.5% / -3.5% |
| Straightness | Full length ≤ 0.2%; Pipe ends (1.5m) ≤ 3.2mm |
| Length Range | R1: 4.88-7.62m; R2: 7.62-10.36m; R3: 10.36-14.63m |
N80-1 vs N80Q: How to Choose
| Item | N80-1 | N80Q |
|---|---|---|
| Heat treatment | As-rolled or normalized | Quenched and tempered (full body) |
| Yield strength | 80,000 - 110,000 psi (552 - 758 MPa) | 80,000 - 110,000 psi (552 - 758 MPa) |
| Min tensile | 100,000 psi (689 MPa) | 100,000 psi (689 MPa) |
| CVN impact test | Not mandatory (PSL2 adds it) | Mandatory per SR16 |
| Color band | One red band | One red + one bright green band |
| Relative cost | Lower | Higher |
| Best for | Standard wells, cost-driven projects | Deep wells, complex geology, low temperature or impact critical strings |
N80 vs K55 vs L80-1 vs P110 Selection Guide
| Item | K55 | N80 (1/Q) | L80-1 | P110 |
|---|---|---|---|---|
| API group | Group 1 | Group 1 | Group 2 | Group 3 |
| Yield, psi | 55,000 - 80,000 | 80,000 - 110,000 | 80,000 - 95,000 | 110,000 - 140,000 |
| Min tensile, psi | 95,000 | 100,000 | 95,000 | 125,000 |
| Max hardness | Not specified | Not specified | 23 HRC | Not specified |
| Sour service (H2S) | No | No | Yes (NACE MR0175) | No |
| Typical well depth | Shallow, < 2,000 m | 3,000 - 4,500 m | Sour or CO2 wells | Deep, high pressure |
| Relative cost | Lowest | Medium | Higher | Highest |
For full comparisons see our API 5CT K55 BTC casing pipe and API 5CT L80 casing pipe pages.
Connections, PSL Level and Order Options
| Option | Available | Notes |
|---|---|---|
| STC (short round thread) | Yes | Lowest cost, low sealing duty |
| LTC (long round thread) | Yes | Standard for 7" and larger casing strings |
| BTC (buttress thread) | Yes | Highest API thread strength and sealing |
| Premium connection | Machined on request | VAM / TenarisHydril type equivalents for HPHT wells |
| PSL1 / PSL2 | Both | PSL2 tightens P and S, adds CVN impact and NDT |
| Coupling type | Loose or made-up | STC/LTC/BTC couplings per API 5B |
API 5CT N80 Casing Pipe Price
Indicative FOB China prices, November 2026. Firm quotation depends on size, wall, connection, PSL level and quantity.
| Item | Indicative FOB price, USD/ton |
|---|---|
| Plain end N80 casing, common sizes | 950 - 1,150 |
| Threaded and coupled (STC / LTC / BTC) | 1,050 - 1,300 |
| N80Q (Q&T, PSL2) | + USD 50 - 120 per ton over N80-1 |
| Premium connection machining | By connection type and size |
MOQ: 5 tons for stock sizes; 20 tons for production orders.
Delivery Time
| Order type | Lead time |
|---|---|
| Stock 5-1/2" and 7" sizes | 7 - 15 days |
| Production order (20 - 200 tons) | 20 - 35 days |
| R3 lengths / premium connections | 30 - 45 days |
API 5CT N80 oil well drilling pipe in stock
Inspection & Testing
To ensure the high-strength performance of N80, the following tests are required:
Hydrostatic Test: Mandatory for every length to verify integrity under high pressure.
Drift Test: Ensures no internal obstructions, following API standard dimensions.
Non-Destructive Testing (NDT): Typically Ultrasonic Testing (UT) or Electromagnetic Induction (EMI).
Charpy V-Notch Impact Test: Mandatory for N80-Q only.
Flattening Test: Conducted to verify the ductility and toughness of the material.
Packaging and shipping
N80 casing ships with thread protectors on both ends, bundled with steel strapping or crated for small OD. Every bundle carries export marks matching the heat numbers on the MTR for full traceability. Couplings are supplied loose or made-up per order, and accessories such as casing shoes, float equipment and pup joints can be loaded in the same container. Shipping is arranged by road, rail or sea (FCL or break-bulk for 20" sizes).
How to Order API 5CT N80 Casing Pipe
Send your enquiry with size (OD x weight per foot), grade (N80-1 or N80Q), connection, PSL level, length range (R1/R2/R3) and destination port - our OCTG sales engineers reply with a firm quotation within 24 hours.
GNEE API 5CT N80 OCTG Casing Pipe process line
GNEE API 5CT N80 Casing Pipe test equipments
GNEE API 5CT N80 Oil well casing pipe certificate
FAQ
Q1: What is the actual difference between N80-1 and N80-Q? Which one should I choose?
A: Their strength ratings are identical. The difference is the heat treatment: N80-1 is Normalized (lower cost, suitable for standard wells), while N80-Q is Quenched & Tempered (better toughness). If your project requires impact toughness or involves complex geology, N80-Q is the recommended choice.
Q2: Can N80 be used in sour environments containing Hydrogen Sulfide (H2S)?
A: No. N80 is a standard steel grade and does not have anti-sour properties. It is susceptible to Sulfide Stress Cracking (SSC) in sour environments. For such conditions, please choose L80-1, C90, or T95.
Q3: Which thread connections do you provide?
A: We provide all API-standard threads, including Short Round Thread (STC), Long Round Thread (LTC), and Buttress Thread (BTC). Additionally, we offer processing for Premium Connections for high-sealing requirements.
Q4: How is N80 casing identified by color bands?
A: According to API 5CT, N80-1 is marked with one red band on the pipe body and coupling. N80-Q is identified by one red band and one green band. This prevents mixing different grades at the rig site.
Q5: What are your inspection standards?
A: We perform 100% of the inspections required by API 5CT, including Hydrostatic Testing, Drift Testing, Ultrasonic Testing (UT), or Magnetic Particle Inspection (MPI). All products are delivered with original Mill Test Reports (MTR).
Q6: What is the difference between API 5CT N80 casing and K55 casing?
Both are Group 1 grades, but K55 has a minimum yield of only 55,000 psi (379 MPa) with no upper limit, while N80 ranges 80,000-110,000 psi (552-758 MPa) with a 100,000 psi minimum tensile. N80-1 additionally requires a normalized heat treatment, and its higher collapse and burst resistance suits wells deeper than about 3,000 m. K55 remains the economical choice for shallow, low-pressure wells.
Q7: What sizes, weights and connections are available for N80 casing?
Outside diameters from 4-1/2 inch to 20 inch with nominal weights from 9.5 to 133 lb/ft, in R1 (4.88-7.62 m), R2 (7.62-10.36 m) and R3 (10.36-14.63 m) lengths. Popular strings are 5-1/2 inch, 7 inch and 9-5/8 inch. Threads include STC, LTC and BTC, and premium connections can be machined on request.
Q8: What is the difference between PSL1 and PSL2 for N80 casing?
PSL2 tightens the chemical limits (P max 0.020%, S max 0.010%), adds mandatory Charpy V-notch impact testing, and requires NDT of the pipe body. N80Q is by definition supplied to PSL2-level impact requirements (SR16). Specify PSL whenever the well design or H2S contingency requires verified toughness.
Q9: How much does API 5CT N80 casing pipe cost and what is the delivery time?
Indicative FOB China price is about USD 950-1,300 per ton depending on size, wall thickness, connection type (plain-end vs threaded and coupled) and PSL level, November 2026 market. Stock 5-1/2 and 7 inch sizes ship in 7-15 days; production orders take 20-35 days, and R3 or premium-connection orders 30-45 days. Email pipes@gneetube.com for a firm quotation.
Q10: How is API 5CT N80 casing packed for export?
Each joint gets thread protectors (plastic or steel) on both ends, pipes are bundled with steel strapping or packed in wooden boxes for small OD, and every bundle carries export marks matching the heat numbers on the MTR. Couplings can be loose or made-up, and accessories such as casing shoes and pup joints ship in the same container.
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