API 5CT casing typically ranges in outer diameter from 114.3 mm to 508 mm (4.5 inches to 20 inches) and wall thickness from 3.18 mm to 22.2 mm, depending on steel grade, application, and well condition design.
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API 5CT Common Casing Size Specification Table
| Nominal OD (inch) | OD (mm) | Nominal Weight (lb/ft) | Wall Thickness (mm) | ID (mm) | Drift Diameter (mm) | Primary Application |
| 4-1/2" | 114.30 | 9.50 | 5.21 | 103.88 | 100.71 | Slim hole production casing / Liner |
| 11.60 | 6.35 | 101.60 | 98.42 | |||
| 13.50 | 7.37 | 99.56 | 96.39 | |||
| 5" | 127.00 | 11.50 | 5.59 | 115.82 | 112.65 | Production casing / Liner |
| 15.00 | 7.52 | 111.96 | 108.79 | |||
| 5-1/2" | 139.70 | 14.00 | 6.22 | 127.26 | 124.08 | Most common production casing |
| 15.50 | 6.98 | 125.74 | 122.56 | |||
| 17.00 | 7.72 | 124.26 | 121.08 | |||
| 20.00 | 9.17 | 121.36 | 118.19 | |||
| 7" | 177.80 | 20.00 | 6.91 | 163.98 | 160.81 | Common intermediate/production |
| 23.00 | 8.05 | 161.70 | 158.52 | |||
| 26.00 | 9.19 | 159.42 | 156.24 | |||
| 29.00 | 10.36 | 157.08 | 153.90 | |||
| 9-5/8" | 244.48 | 36.00 | 8.94 | 226.58 | 222.61 | Most common intermediate casing |
| 40.00 | 10.03 | 224.42 | 220.45 | |||
| 47.00 | 11.99 | 220.50 | 216.54 | |||
| 53.50 | 13.84 | 216.80 | 212.83 | |||
| 10-3/4" | 273.05 | 40.50 | 8.89 | 255.27 | 251.31 | Surface or intermediate casing |
| 45.50 | 10.16 | 252.73 | 248.77 | |||
| 13-3/8" | 339.72 | 48.00 | 8.38 | 322.96 | 319.00 | Standard surface casing |
| 54.50 | 9.65 | 320.42 | 316.46 | |||
| 61.00 | 10.92 | 317.88 | 313.92 | |||
| 68.00 | 12.19 | 315.34 | 311.38 | |||
| 20" | 508.00 | 94.00 | 11.13 | 485.74 | 481.79 | Conductor or surface casing |
| 133.00 | 16.13 | 475.74 | 471.78 |
Steel Grades & Mechanical Properties Table
| Steel Grade | Min. Yield Strength (psi / MPa) | Max. Yield Strength (psi / MPa) | Min. Tensile Strength (psi / MPa) | Common Service Environment |
| H40 | 40,000 / 276 | 80,000 / 552 | 60,000 / 414 | Shallow wells, low pressure |
| J55 | 55,000 / 379 | 80,000 / 552 | 75,000 / 517 | Standard oil and gas wells |
| K55 | 55,000 / 379 | 80,000 / 552 | 95,000 / 655 | Similar to J55, higher tensile |
| N80-1/Q | 80,000 / 552 | 110,000 / 758 | 100,000 / 689 | Medium depth, complex formations |
| L80-1 | 80,000 / 552 | 95,000 / 655 | 95,000 / 655 | Sour Service (
H2SH2S Resistance) |
| C90 | 90,000 / 621 | 105,000 / 724 | 100,000 / 689 | High-pressure sour wells |
| P110 | 110,000 / 758 | 140,000 / 965 | 125,000 / 862 | Deep wells, high-pressure (HPHT) |
| Q125 | 125,000 / 862 | 150,000 / 1034 | 135,000 / 931 | Ultra-deep/Extreme pressure wells |
Steel Grade (Strength & Environment)
J55/K55: General purpose for shallow, low-pressure wells. Cost-effective.
N80/L80: Medium strength. L80 is specifically designed for
H2SH2S
(sour gas) resistance.
P110: High strength for deep, high-pressure wells.
Q125: Ultra-high strength for extreme HPHT (High Pressure High Temperature) environments.
Connection Types
STC (Short Threaded and Coupled): Used for shallow wells with low tension loads.
LTC (Long Threaded and Coupled): Provides better tensile strength than STC.
BTC (Buttress Threaded and Coupled): High tensile and compression strength. It is the most widely used connection for standard casing.
Premium Connections: Proprietary threads (e.g., VAM, TenarisHydril) that provide gas-tight metal-to-metal seals for high-pressure gas wells.
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FAQ
What are the common casing sizes?
Casing Pipe Size range: 5 1/2 "to 20" Length usually in R3. Tubing Pipe dimensions range: 1.0 ", 1.315", 1.66 ", 1.9", 2.063 ", 2 3/8", 3 1/2 "and 4 1 /2", Length in R2.
What is the wall thickness tolerance for API 5ct?
-12.5%
Tolerance for casing and tubing wall thickness is -12.5%.
What is the difference between API 5B and 5CT?
The specification for the threads themselves-their shape, dimensions, and tolerances-is API 5B. However, the specification for the actual pipe body, which covers the steel's chemical composition, its mechanical properties like yield strength, and the heat treatment it undergoes, is covered by API 5CT.
