API 5CT H40 Casing And Tubing
What is API 5CT H40 OCTG?
Grade Level: Entry-level (Lowest strength).
Yield Strength: Minimum of 40,000 psi.
Application: Used for surface casing or tubing in shallow, low-pressure wells. It is highly economical compared to J55 or N80.
Manufacturing: Can be Seamless (S) or Electric Welded (EW).
Chemical Composition & Mechanical Analysis (H40)
API 5CT focuses on limiting harmful impurities (Phosphorus and Sulfur) for this grade, as the strength requirement is relatively easy to achieve with standard carbon steel.
Chemical Composition (Mass Fraction %)
| Grade | Phosphorus (P) | Sulfur (S) |
| H40 | ≤ 0.030% | ≤ 0.030% |
Mechanical Property Table
| Property | Imperial Units | Metric Units |
| Yield Strength (Min - Max) | 40,000 – 80,000 psi | 276 – 552 MPa |
| Tensile Strength (Min) | 60,000 psi | 414 MPa |
| Hardness | Not Specified | Not Specified |
| Elongation | Calculated based on specimen area | Calculated based on specimen area |
Specification & Size Chart: H40 Tubing
H40 tubing is used for production in very low-pressure shallow wells.
| Outer Diameter (inch) | OD (mm) | Weight (lb/ft) | Wall Thickness (mm) | End Connection |
| 2-3/8" | 60.3 | 4.00 - 4.60 | 4.24 - 4.83 | NU / EUE |
| 2-7/8" | 73.0 | 6.40 | 5.51 | NU / EUE |
| 3-1/2" | 88.9 | 7.70 - 9.20 | 5.49 - 6.45 | NU / EUE |
| 4-1/2" | 114.3 | 12.60 | 6.88 | NU / EUE |
Specification & Size Chart: H40 Casing
H40 casing is most commonly used as surface casing to protect groundwater from contamination in shallow drilling.
| Outer Diameter (inch) | OD (mm) | Weight (lb/ft) | Wall Thickness (mm) | Connection Type |
| 4-1/2" | 114.3 | 9.50 | 5.21 | STC / LTC |
| 5-1/2" | 139.7 | 14.00 | 6.22 | STC / LTC |
| 7" | 177.8 | 17.00 - 20.00 | 5.87 - 6.91 | STC / LTC |
| 8-5/8" | 219.1 | 24.00 | 6.71 | STC |
| 9-5/8" | 244.5 | 32.30 | 7.92 | STC |
| 13-3/8" | 339.7 | 48.00 | 8.38 | STC |
| 20" | 508.0 | 94.00 | 11.13 | BTC |
Identification of Color Bands for H40
To prevent confusion at the well site, API uses specific color codes.
| Item | Color Identification |
| Pipe Body | No Color Band (Standard) |
| Coupling Body | No Color Band (Often just black/clear varnish) |
| Alternative Marking | Sometimes marked with a clear varnish or simply stamped "H40" |
Inspection of API 5CT H40
Since H40 is a low-strength grade, the inspection requirements are the basic API mandatory tests (PSL-1).
Visual Inspection: Checking the internal and external surfaces for defects like pits, gouges, or scale.
Hydrostatic Test: Every length of pipe is tested with water at high pressure (typically 3,000 psi or less for H40) to ensure no leaks.
Dimensional Inspection: Measuring Outside Diameter (OD), Wall Thickness, and Length (R1, R2, or R3).
Drift Test: A cylindrical mandrel is passed through the entire length of the pipe to ensure tools can pass through later.
Thread Inspection: Checking thread lead, height, and taper using API gauges.
NDT (Optional for H40): While higher grades require 100% NDT, H40 usually only requires it if specified by the purchase order or if it is Electric Welded (EW) to check the weld seam.
API 5CT H40 OCTG Factory
FAQ
What is the wall thickness tolerance for API 5CT?
In the API 5CT standard, the wall thickness tolerance for casing and tubing is typically 0 to -12.5%; that is, a negative deviation in wall thickness is permitted, but a positive deviation is not. The specific values are determined based on the product specifications and PSL level.
What is the difference between API 5CT and API 5L?
API 5CT and API 5L are two distinct standards for petroleum tubular goods, serving different applications: API 5CT applies to casing and tubing used within oil wells, emphasizing collapse resistance, corrosion resistance, and thread seal integrity; API 5L applies to surface pipelines for transportation, prioritizing weld quality, toughness, and strength consistency over long distances.
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