API 5CT is the international standard for casing and tubing used in oil and gas wells. It specifies the chemical composition and mechanical properties of various steel grades to ensure safe operation under high pressure, high temperature, and corrosive environments. The most common grades include J55, K55, N80, L80, and P110. Each grade is designed for specific well conditions, such as shallow wells, deep wells, or sour service (H2S environments).
Chemical Composition (Max %)
Typical maximum chemical composition (% by mass) per API 5CT.
| Grade | Type | C (%) | Mn (%) | P (%) | S (%) |
|---|---|---|---|---|---|
| J55 | Carbon Steel | — | — | ≤0.030 | ≤0.030 |
| K55 | Carbon Steel | — | — | ≤0.030 | ≤0.030 |
| N80 | Carbon Steel | — | — | ≤0.030 | ≤0.030 |
| L80 | Alloy Steel | ≤0.43 | ≤1.90 | ≤0.030 | ≤0.030 |
| P110 | Alloy Steel | — | — | ≤0.030 | ≤0.030 |
Note: J55, K55, and N80 are carbon steels. L80 and P110 are alloy steels. L80 is specifically designed for sour service (H2S environments) and is available in L80-1, L80-9Cr, and L80-13Cr variants.
Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Hardness (HRC) |
|---|---|---|---|---|
| J55 | 379–552 | ≥517 | ≥15 | — |
| K55 | 379–552 | ≥655 | ≥15 | — |
| N80 | 552–758 | ≥689 | ≥11 | — |
| L80 | 552–655 | ≥655 | ≥14 | ≤23 |
| P110 | 758–965 | ≥862 | ≥12 | — |
Available Sizes & Delivery
| Outer Diameter (OD) | 114.3–508 mm (4-1/2″ to 20″) |
| Wall Thickness (WT) | 5.21–16.13 mm |
| Length | R1 (4.88–7.62m), R2 (7.62–10.36m), R3 (10.36–14.63m) |
| Connection Types | STC (Short Thread), LTC (Long Thread), BTC (Buttress Thread) |
| Standard | API 5CT / ISO 11960 |
| Mill Test Certificate | EN 10204 3.1 with every shipment |
| MOQ | 10 Tons |
| Delivery Time | Within 20-30 days (≤1000 tons) |
Why Order from Zhongtang Steel?
- Full API 5CT Range — J55, K55, N80, L80, and P110 available
- Sour Service Options — L80-1 and L80-13Cr for H2S environments
- Premium Connections — STC, LTC, and BTC threading available
- EN 10204 3.1 MTC supplied with every shipment
- ISO 9001 certified manufacturer since 1998
Applications
- Oil and gas well casing and tubing
- Water injection wells and disposal wells
- Geothermal wells and underground storage
- Sour gas wells (L80 grades)
- Deep and ultra-deep wells (P110)
- Offshore and onshore drilling operations
Values are typical reference ranges per API 5CT. Actual properties may vary by pipe type and production route. Mill test certificates (EN 10204 3.1) are supplied with every shipment — contact us for exact data sheets.
