Under the API 5CT specification, N80 casing is available in a wide range of standard industry sizes, typically ranging from 4-1/2" to 20" in outer diameter (OD).
The actual size you choose depends on the well design (Surface, Intermediate, or Production casing).
Download the Full N80 Casing Size and Weight Chart (PDF) – Your Free Technical Resource.
N80 Casing Size Chart: Production Casing/Liners (4-1/2" - 7")
These sizes are commonly used as Production Casing or Liners for the reservoir section.
| Outer Diameter (OD) | Nominal Weight | Wall Thickness | Inner Diameter (ID) | Drift Diameter |
| inch (mm) | lb/ft ( kg/m ) | inch (mm) | inch (mm) | inch (mm) |
| 4-1/2" (114.30) | 9.50 (14.14) | 0.205 (5.21) | 4.090 (103.89) | 3.965 (100.71) |
| 11.60 (17.26) | 0.250 (6.35) | 4.000 (101.60) | 3.875 (98.43) | |
| 13.50 (20.09) | 0.290 (7.37) | 3.920 (99.57) | 3.795 (96.39) | |
| 5-1/2" (139.70) | 15.50 (23.07) | 0.275 (6.98) | 4.950 (125.73) | 4.825 (122.56) |
| 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" (177.80) | 23.00 (34.23) | 0.317 (8.05) | 6.366 (161.70) | 6.241 (158.52) |
| 26.00 (38.69) | 0.362 (9.19) | 6.276 (159.41) | 6.151 (156.23) | |
| 29.00 (43.16) | 0.408 (10.36) | 6.184 (157.07) | 6.059 (153.90) | |
| 32.00 (47.62) | 0.453 (11.51) | 6.094 (154.79) | 5.969 (151.61) |
N80 Casing Size Chart: Intermediate/Surface Casing (9-5/8" - 13-3/8")
These sizes are typically used for Intermediate Casing or Surface Casing.
| Outer Diameter (OD) | Nominal Weight | Wall Thickness | Inner Diameter (ID) | Drift Diameter |
| inch (mm) | lb/ft ( kg/m ) | inch (mm) | inch (mm) | inch (mm) |
| 9-5/8" (244.48) | 36.00 (53.57) | 0.352 (8.94) | 8.921 (226.59) | 8.765 (222.63) |
| 40.00 (59.53) | 0.395 (10.03) | 8.835 (224.41) | 8.679 (220.45) | |
| 43.50 (64.73) | 0.435 (11.05) | 8.755 (222.38) | 8.599 (218.41) | |
| 47.00 (69.94) | 0.472 (11.99) | 8.681 (220.50) | 8.525 (216.53) | |
| 13-3/8" (339.72) | 48.00 (71.43) | 0.330 (8.38) | 12.715 (322.96) | 12.559 (319.00) |
| 54.50 (81.10) | 0.380 (9.65) | 12.615 (320.42) | 12.459 (316.46) | |
| 61.00 (90.78) | 0.430 (10.92) | 12.515 (317.88) | 12.359 (313.92) | |
| 68.00 (101.19) | 0.480 (12.19) | 12.415 (315.34) | 12.259 (311.38) |
N80 Casing Size Chart: Large Diameter/Conductor (16" - 20")
| Outer Diameter (OD) | Nominal Weight | Wall Thickness | Inner Diameter (ID) | Drift Diameter |
| inch (mm) | lb/ft ( kg/m ) | inch (mm) | inch (mm) | inch (mm) |
| 16" (406.40) | 65.00 (96.73) | 0.375 (9.53) | 15.250 (387.35) | 15.062 (382.57) |
| 75.00 (111.61) | 0.438 (11.13) | 15.124 (384.15) | 14.936 (379.37) | |
| 20" (508.00) | 94.00 (139.89) | 0.438 (11.13) | 19.124 (485.75) | 18.936 (480.97) |
| 106.50 (158.49) | 0.500 (12.70) | 19.000 (482.60) | 18.812 (477.82) | |
| 133.00 (197.93) | 0.635 (16.13) | 18.730 (475.74) | 18.542 (470.97) |
Length Ranges
API classifies casing lengths into three ranges. Range 3 is the most common for N80 casing.
Range 1 (R1): 16.0 – 25.0 ft (4.88 – 7.62 m)
Range 2 (R2): 25.0 – 34.0 ft (7.62 – 10.36 m)
Range 3 (R3): 34.0 – 48.0 ft (10.36 – 14.63 m) - Most widely used industry standard.
Common Connection (Thread) Types
LTC (Long Thread Coupled): Long round thread. This is the most common standard for N80 casing.
BTC (Buttress Thread Coupled): Used for large diameter wells or sections with high tensile loads.
STC (Short Thread Coupled): Short round thread. Typically used for shallow wells with lower loads.
Premium Connections: Gas-tight connections used for high-pressure, deviated, or critical wells.
API 5CT Casing factory
API 5CT N80 Casing Test equpments
FAQ
What is an N80 pipe?
An N80 pipe is a specific grade of steel casing or tubing used in oil and gas drilling, governed by the API 5CT standard.
Strength: It has a yield strength ranging from 80,000 to 110,000 psi (the "80" refers to the minimum yield strength of 80 ksi).
Two Types:
N80-1: Normalized steel (cheaper, standard processing).
N80-Q: Quenched and tempered steel (higher toughness and strength).
Application: It is typically used in medium-depth oil and gas wells where higher pressure resistance is needed compared to lower grades like J55 or K55.
Usage: It serves as a structural retainer for the walls of oil and gas wells (casing) or as the conduit through which oil/gas is brought to the surface (tubing).
What is the yield strength of N80 casing?
The yield strength of N80 casing is:
Minimum: 80,000 psi (552 MPa)
Maximum: 110,000 psi (758 MPa)
