Premium API 5CT Casing Pipe
Our API Casing pipes are engineered to serve as the structural retainer for oil and gas wells, offering superior hole integrity and preventing borehole collapse. Manufactured from high-quality strong steel, these pipes withstand immense axial tension and aggressive subsurface environments.
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Standard: API SPEC 5CT / ISO 11960
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Size Range: OD: 4.5″ – 36″ (114.3mm – 508mm standard) | WT: 5.21mm – 16.13mm
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Process Type: Seamless (SMLS) and Electric Resistance Welded (ERW)
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Grades Available: H40, J55, K55, M65, N80 (Type 1 & Q), L80 (Type 1, 9Cr, 13Cr), C90, T95, C110, P110, Q125
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Thread Types: Plain End (P), Short Round Thread (S), Long Round Thread (L), Buttress Thread (B), Extreme Line (E)
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Applications: Conductor Casing, Surface Casing, Intermediate Casing, Production Casing, and Production Liners.
Description
1. Product Overview & Application
Casing is used for lining the complete borehole which has been dug into the ground to procure oil. Similar to drill pipe, the oil well casing pipe is subjected to axial tension, requiring it to be manufactured from high-quality, high-strength steel. OCTG casing comprises large-diameter pipes held in place in the borehole using cement.
The diameters of our OCTG casing pipes range from 4.5″ to 36″. The well-cemented pipe acts as the structural component of the well, offering hole integrity and preventing the well from collapsing during the drilling process. Good quality, well-cemented casing can stay in place for the entire lifespan of the well.
Types of Oil Well Casing:
- Conductor Casing: The first boundary between the surface and subsurface. It prevents well collapse, keeps away groundwater, and provides structural support. Installed by drilling or hammering. Sizes range from 18″ to 36″.
- Surface Casing: Primarily for environmental protection and safety. Separates freshwater zones, offers blowout protection, and supports the wellhead and Blow Out Preventer (BOP). Maintains very high safety standards. The most common size is 13-3/8″.
- Intermediate Casing: Placed between the surface and production casing when necessary. Sizes generally range from 13-3/8″ to 16″.
- Production Casing: Provides structural integrity and pressure control of the hydrocarbon-bearing sections primarily during oil production.
- Production Liner: Suspended from the production casing or a previous casing. Reduces costs significantly as it doesn’t run the full depth of the well. Can be pre-perforated to save time and costs.
2. Dimensions, Lengths & Tolerances
API 5CT Well Casing Length Ranges
| Range 1 | Range 2 | Range 3 |
|---|---|---|
| 4.88 ~ 7.62 meters | 7.62 ~ 10.36 meters | 10.36 ~ 14.63 meters |
Dimension Tolerances
| Parameter | Tolerance | |
|---|---|---|
| Outside Diameter (D) | Pipe Body | D ≤ 101.60mm: ±0.79mm D ≥ 114.30mm: +1.0%, -0.5%D |
| Coupling | ±1%D | |
| Wall Thickness (t) | 0, -12.5%t | |
| Weight | Single Lengths | +6.5%, -3.5% |
| Carload Lots / Order Qty | ≥ 18144 kg: 0, -1.75% < 18144 kg: 0, -3.5% |
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3. Chemical Composition & Mechanical Properties (API Spec 5CT / ISO 11960)
Chemical Composition, Mass Fraction (%)
| Steel Grade | C | Mn | Mo | Cr | Ni | Cu | P | S | Si | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | Max | Min | Max | Min | Max | Max | Max | Max | Max | Max | Max | |
| H40 / J55 / K55 | – | – | – | – | – | – | – | – | – | 0.030 | 0.030 | – |
| N80 (1 & Q) | – | – | – | – | – | – | – | – | – | 0.030 | 0.030 | – |
| L80 (Type 1) | – | 0.43 | – | 1.90 | – | – | – | 0.25 | 0.35 | 0.030 | 0.030 | 0.45 |
| L80 9Cr | – | 0.15 | 0.30 | 0.60 | 0.90 | 1.10 | 8.00~10.0 | 0.50 | 0.25 | 0.020 | 0.010 | 1.00 |
| L80 13Cr | 0.15 | 0.22 | 0.25 | 1.00 | – | – | 12.0~14.0 | 0.50 | 0.25 | 0.020 | 0.010 | 1.00 |
| P110 | – | – | – | – | – | – | – | – | – | 0.030 | 0.030 | – |
| Q125 | – | 0.35 | – | 1.35 | – | 0.85 | 1.50 | 0.99 | – | 0.020 | 0.010 | – |
Mechanical Properties
| Grade | Total Elongation Under Load (%) | Yield Strength Min (MPa) | Yield Strength Max (MPa) | Tensile Strength Min (MPa) | Hardness Max (HRC / HBW) |
|---|---|---|---|---|---|
| J55 / K55 | 0.5 | 379 | 552 | 517 (J55) / 655 (K55) | – |
| N80 (1 & Q) | 0.5 | 552 | 758 | 689 | – |
| L80 (1, 9Cr, 13Cr) | 0.5 | 552 | 655 | 655 | 23 HRC / 241 HBW |
| C90 | 0.5 | 621 | 724 | 689 | 25.4 HRC / 255 HBW |
| P110 | 0.6 | 758 | 965 | 862 | – |
| Q125 | 0.65 | 862 | 1034 | 931 | – |
4. Available Thread Connections
We supply API casing with a variety of threading options tailored to your specific application requirements. Standard thread symbols include:
- P: Plain end
- S / STC: Short round thread
- L / LTC: Long round thread
- B / BTC: Buttress thread
- E: Extreme line
5. Manufacturing Process of API Casing
Our API OCTG casing goes through a rigorous, high-standard manufacturing process to ensure reliability in extreme downhole conditions:
- Ingot Heating: An annular heating furnace is used for initial steel ingot heating.
- Hydraulic Punching & Reheating: Conducted using a heavy-duty hydraulic press.
- Extension: The oil casing plant uses a two-roller guide plate extension machine.
- Periodic Rolling & Finishing: A disc heating furnace is utilized for periodic rolling. Following this, a non-entry furnace manages reheating, cooling, sizing, straightening, pipe cutting, and final non-destructive inspection.
Complete API Casing Manufacturing and Inspection Flow