API 5CT L80-9Cr Casing Pipe is a corrosion-resistant alloy (CRA) steel pipe specifically designed for oil and gas wells with moderate CO2(carbon dioxide) concentrations. It serves as a middle-ground solution between the standard carbon steel (L80-1) and the high-chromium stainless steel (L80-13Cr).
L80-9Cr belongs to Group 2 of the API 5CT specification. It is a martensitic alloy steel that must undergo Quenching and Tempering (Q&T).
Corrosion Resistance: The "9Cr" indicates a 9% Chromium content, which provides better resistance to weight-loss corrosion caused by
CO2 than standard carbon steel.
Restricted Yield/Hardness: Like all L80 grades, it has a strictly controlled yield strength range and a maximum hardness of 23 HRC to prevent Sulfide Stress Cracking (SSC).
Application: It is typically used in "Sweet Service" wells where CO2 levels are present but not severe enough to justify the much higher cost of 13Cr.
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Identification of Color Band for L80-9Cr
| Grade | Body Color Bands | Coupling Color |
| L80 9Cr | One Red + One Brown + Two Yellow | Brown |
API 5CT L80-9Cr Casing Specification Table
| Item | Details |
| Standard | API Spec 5CT |
| Steel Grade | L80 Type 9Cr |
| Group | Group 2 (Restricted yield and hardness) |
| Manufacturing | Seamless (SML) is standard |
| Heat Treatment | Quenched and Tempered (Q&T) |
| Service Environment | Moderate CO2 (Sweet Service) |
API 5CT L80 9Cr Chemical Composition Table
The core strength of L80 9Cr lies in its 9.0% Chromium and 1.0% Molybdenum content. This combination makes it significantly superior to standard L80 Type 1 carbon steel in resisting uniform weight-loss corrosion.
| Element | Content Range / Maximum (Weight %) |
| Carbon (C) | ≤ 0.15 |
| Manganese (Mn) | 0.30 - 0.60 |
| Phosphorus (P) | ≤ 0.020 |
| Sulfur (S) | ≤ 0.010 |
| Silicon (Si) | 0.90 - 1.10 |
| Chromium (Cr) | 8.00 - 10.00 |
| Molybdenum (Mo) | 0.90 - 1.10 |
| Nickel (Ni) | ≤ 0.50 |
| Copper (Cu) | ≤ 0.25 |
API 5CT L80 9Cr Mechanical Properties Table
L80 9Cr requires a strict yield strength range and precise hardness control to ensure structural reliability in corrosive environments.
| Mechanical Property | US Customary (psi) | Metric / SI (MPa) |
| Yield Strength (Minimum) | 80,000 psi | 552 MPa |
| Yield Strength (Maximum) | 95,000 psi | 655 MPa |
| Tensile Strength (Minimum) | 95,000 psi | 655 MPa |
| Maximum Hardness | 23 HRC | 241 HBW |
| Elongation | Based on API Formula* | Based on API Formula* |
*Note: Minimum elongation is calculated based on the cross-sectional area of the tensile specimen, typically requiring 15% or higher.
API 5CT L80-9Cr Casing Size Table (Common Sizes)
| Nominal Size (in) | OD (mm) | Wall Thickness (mm) | Nominal Weight (lb/ft) | Drift Diameter (mm) |
| 4-1/2 | 114.30 | 6.35 | 11.60 | 99.21 |
| 5-1/2 | 139.70 | 7.72 | 17.00 | 121.87 |
| 7 | 177.80 | 9.19 | 26.00 | 156.24 |
| 9-5/8 | 244.48 | 11.99 | 47.00 | 216.53 |
API 5CT L80-9Cr Casing Dimension Tolerance Table
| Parameter | API 5CT Tolerance |
| Outside Diameter (OD) | < 4-1/2": ±0.031" / ≥ 4-1/2": -0.5% to +1.0% |
| Wall Thickness | -12.5% |
| Weight | -3.5% to +6.5% (Single Length) |
| Inside Diameter (ID) | Controlled by the Drift Mandrel size |
| Straightness | Max 0.2% of total length |
API 5CT L80-9Cr Casing Test Table
| Test Type | Frequency/Requirement | Purpose |
| Hardness Test | Per joint or per heat | Ensures < 23 HRC to resist
H2SH2S cracking. |
| Tensile Test | One per heat/lot | Verifies Yield and Tensile strength. |
| Hydrostatic Test | 100% of joints | Verifies leak-proof performance under pressure. |
| NDT (Non-Destructive) | 100% of joints | Ultrasonic or Eddy Current to find internal flaws. |
| Drift Test | 100% of joints | Ensures downhole tools can pass through. |
| Visual Inspection | 100% of joints | Checks for surface pits, cracks, or thread damage. |
| Impact Test | Required for PSL2/3 | Verifies low-temperature toughness (Charpy V-Notch). |
API 5CT L80-9Cr oil well casing factory
API 5CT L80-9Cr Casing certificate
FAQ
Are L80 9Cr available as welded pipe?
No, API 5CT L80 9Cr is only available as Seamless (SML) pipe.
Here are the 2 main reasons why:
API 5CT Requirement: The API 5CT specification mandates that high-alloy martensitic grades, specifically 9Cr and 13Cr, must be manufactured using the seamless process. Unlike L80 Type 1, welded versions (ERW) are not permitted for these alloys.
Welding Difficulty: Steel with 9% chromium is technically difficult to weld longitudinally. The heat from welding can create brittle zones and destroy the material's corrosion resistance at the seam, making it unsafe for high-pressure oil and gas environments.
When is L80-9Cr commonly specified for casing and tubing programs?
Specify L80-9Cr when you need better CO2 protection than carbon steel but want to save money compared to 13Cr stainless steel.
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