API 5CT P110 is a high-strength grade of casing and tubing pipe widely used in the oil and gas industry, defined by the API Specification 5CT (American Petroleum Institute). It is a quenched and tempered steel, offering a minimum yield strength of 110,000 psi (758 MPa), making it suitable for deep, high-pressure wells.
Key Characteristics & Applications
High Strength: Its primary advantage is its high yield strength, which allows it to withstand the high mechanical loads and internal pressures encountered in deep wells.
Non-Sour Service: P110 is generally not recommended for sour service (environments containing hydrogen sulfide, H₂S) unless specifically agreed upon by the purchaser and manufacturer with additional testing. It is susceptible to Sulfide Stress Cracking (SSC).
Common Applications:
Production casing in deep vertical wells.
Intermediate/technical casing in demanding formations.
Surface casing in high-pressure regions.
It is often used in deep, high-pressure, but non-corrosive (sweet) environments.
Product Parameters & Tables
Table 1: Mechanical Properties of API 5CT P110
| Property | Value | Unit | Notes |
|---|---|---|---|
| Grade | P110 | - | - |
| Minimum Yield Strength | 110,000 | psi | 758 MPa |
| Maximum Yield Strength | 140,000 | psi | 965 MPa |
| Minimum Tensile Strength | 125,000 | psi | 862 MPa |
| Hardness (Maximum) | |||
| - Body | 35.5 | HRC | Rockwell C Scale |
| - Weld Seam | 37.0 | HRC | For EW pipes |
| Elongation (Minimum) | See Formula | % | e=625,000A0.2U0.9e=625,000U0.9A0.2 Where: e = elongation in 2-in., % A = cross-sectional area, in² U = tensile strength, psi |
Table 2: Dimensional and Mass Data (Common Sizes - Casing)
This table shows examples. The full range of sizes is specified in API 5CT.
| Outside Diameter (OD) | Weight (Nominal) | Wall Thickness | Inside Diameter (ID) | Plain-End Mass (Approx.) | |||||
|---|---|---|---|---|---|---|---|---|---|
| in | mm | lb/ft | kg/m | in | mm | in | mm | lb/ft | kg/m |
| 5.5 | 139.7 | 17 | 25.3 | 0.304 | 7.72 | 4.892 | 124.3 | 17.0 | 25.3 |
| 5.5 | 139.7 | 20 | 29.8 | 0.361 | 9.17 | 4.778 | 121.4 | 20.0 | 29.8 |
| 7 | 177.8 | 23 | 34.2 | 0.317 | 8.05 | 6.366 | 161.7 | 23.0 | 34.2 |
| 7 | 177.8 | 26 | 38.7 | 0.362 | 9.19 | 6.276 | 159.4 | 26.0 | 38.7 |
| 9 5/8 | 244.5 | 40 | 59.5 | 0.395 | 10.03 | 8.835 | 224.4 | 40.0 | 59.5 |
| 9 5/8 | 244.5 | 47 | 69.9 | 0.472 | 11.99 | 8.681 | 220.5 | 47.0 | 69.9 |
| 13 3/8 | 339.7 | 61 | 90.8 | 0.430 | 10.92 | 12.515 | 317.9 | 61.0 | 90.8 |
| 13 3/8 | 339.7 | 68 | 101.2 | 0.480 | 12.19 | 12.415 | 315.3 | 68.0 | 101.2 |
Note: The mass provided is for plain-end pipe. Threaded and coupled (T&C) pipes will have a different mass.
Table 3: Performance Data - Collapse & Internal Yield Pressure (Example for 7", 26 lb/ft)
| Performance Rating | Pressure (psi) | Pressure (MPa) | Notes |
|---|---|---|---|
| Collapse Resistance | ~9,040 | ~62.3 | This is the theoretical minimum collapse pressure under axial tension-free conditions. Actual performance depends on manufacturing tolerances. |
| Internal Yield Pressure | ~9,760 | ~67.3 | This is the theoretical minimum internal pressure at which yielding occurs, calculated using Barlow's formula. |
Important: The actual collapse and burst pressures are affected by the thread type (e.g., BTC, LTC, STC, or premium connections). The values above are for the pipe body only.
Key Technical Notes
Delivery Condition: P110 is always delivered in the quenched and tempered (Q&T) condition to achieve its high strength and toughness.
Sour Service (H₂S) Warning: Standard P110 is not suitable for sour service. For environments containing H₂S, grades with hardness control like L80 or C110 (Type 2) should be used.
Thread Types: P110 casing can be furnished with various API threads:
STC (Short Thread Coupled)
LTC (Long Thread Coupled)
BTC (Buttress Thread Coupled)
Premium Connections: For critical applications, non-API premium threads (e.g., from Vallourec, Tenaris) offer superior gas-tight sealing and structural performance.
Manufacturing Process: It can be produced as either Seamless (S) or Electric Resistance Welded (EW). Seamless is more common for high-pressure applications.
This information is based on the latest API 5CT specification but is for reference purposes only. For critical engineering and procurement, always consult the full and official API Spec 5CT document.
