L80 is a casing steel grade defined within the API 5CT standard; it specifies a minimum yield strength of 552 MPa (approximately 80 ksi) and falls into the medium-strength category, making it suitable for medium-to-deep wells. L80-1 is a specific variant within the L80 grade-also referred to as "Standard L80" or "Carbon-Manganese L80"-which does not incorporate high concentrations of corrosion-resistant alloying elements such as chromium (Cr) or molybdenum (Mo).
Chemical Composition
| Steel Grade | Carbon (C) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) | Silicon (Si) | Chromium (Cr) | Nickel (Ni) |
| L80-1 | ≤ 0.43% | ≤ 1.90% | ≤ 0.030% | ≤ 0.010% | ≤ 0.45% | - | ≤ 0.25% |
| L80-9Cr | ≤ 0.15% | 0.30-0.60% | ≤ 0.020% | ≤ 0.010% | 0.90-1.10% | 8.0-10.0% | - |
| L80-13Cr | 0.15-0.22% | 0.25-1.00% | ≤ 0.020% | ≤ 0.010% | ≤ 1.00% | 12.0-14.0% | - |
Mechanical Properties
| Property | Unit (Metric) | Value | Unit (Imperial) | Value |
| Yield Strength | MPa | 552 ~ 655 | psi | 80,000 ~ 95,000 |
| Tensile Strength | MPa | ≥ 655 | psi | ≥ 95,000 |
| Max Hardness | HRC | ≤ 23 | HBW | ≤ 241 |
| Elongation | % | Calculated by formula | % | Calculated by formula |
Heat Treatment & Impact Testing
| Item | Requirement |
| Heat Treatment Method | Quenched & Tempered (Q&T) |
| Impact Test (CVN) | Mandatory (Must meet minimum energy requirements per API 5CT) |
| Hardness Test | Mandatory (Every joint must be checked to ensure hardness
≤23≤23 HRC to prevent Sulfide Stress Cracking - SSC) |
Color Identification
| Steel Grade | Color Bands |
| L80-1 | One Red + One Brown |
| L80-9Cr | One Red + One Brown + Two Black |
| L80-13Cr | One Red + One Brown + One Black |
Common Dimensions & Load Capacities
L80 Tubing (Examples)
| Outer Diameter (inch) | Wall Thickness (mm) | Internal Yield (psi) | Collapse Resistance (psi) |
| 2-7/8" (73.02mm) | 5.51 | 10,570 | 11,160 |
| 3-1/2" (88.90mm) | 6.45 | 10,160 | 9,550 |
L80 Casing (Examples)
| Outer Diameter (inch) | Wall Thickness (mm) | Internal Yield (psi) | Collapse Resistance (psi) |
| 5-1/2" | 9.17 | 9,190 | 8,830 |
| 7" | 10.36 | 8,160 | 6,700 |
| 9-5/8" | 11.99 | 6,870 | 3,970 |
API 5CT N80 vs. L80 Core Comparison Table
| Property / Feature | N80 (N80-1 / N80-Q) | L80 (L80-1 / 9Cr / 13Cr) |
| API Group | Group 1 (General Service) | Group 2 (Restricted Yield Service) |
| Min. Yield Strength | 80,000 psi (552 MPa) | 80,000 psi (552 MPa) |
| Max. Yield Strength | 110,000 psi (758 MPa) | 95,000 psi (655 MPa) |
| Min. Tensile Strength | 100,000 psi (689 MPa) | 95,000 psi (655 MPa) |
| Hardness Limit | No strict requirement | Strictly Mandated ≤ 23 HRC (241 HBW) |
| Heat Treatment | N80-1: Normalized; N80-Q: Q&T | Mandatory Quenched & Tempered (Q&T) |
| Sour Service (
H2SH2S ) |
Non-sour service | Sour service (SSC Resistance) |
|
CO2CO2 Resistance |
None | L80-13Cr provides high
CO2CO2 resistance |
| Impact Test (CVN) | Mandatory for N80-Q only | Mandatory for all L80 grades |
| Color Identification | Red | Red + Brown |
| Production Cost | Lower | Higher (due to strict testing/processing) |
Selection Guide: Which one should you buy?
| Your Project Needs | Recommended Grade | Reason |
| Shallow/Medium wells, no acidic gas | N80 (N80-1) | Best cost-to-performance ratio for general physical loads. |
| Wells containing
H2SH2S (Sour Wells) |
L80-1 | Must meet sour service requirements to prevent sudden string failure. |
| Wells with high
CO2CO2 concentration |
L80-13Cr | Protects the string from acidic liquid corrosion and perforation. |
| Deep wells, high load, dry environment | N80-Q | Sufficient strength, cheaper than L80, and better physical properties than N80-1. |
GNEE API 5CT casing and tubing in stock
GNEE Pipe process line
GNEE pipe test and inspection equipment
FAQ
What is the tensile strength of L80?
The L80 Tubing is designed with a minimum tensile strength of 655mpa and has a yield strength between 552 to 655mpa. The API 5CT Tubing is generally found in segments of 30 ft with a threaded connection on both ends.
What is L80 grade?
L80 Steel is a high-strength, low-alloy steel primarily used in the oil and gas industry, particularly for tubular applications such as casing and tubing in drilling operations.
What is the chemical composition of API 5CT L80 Type 1?
The API 5CT L80 Pipe is designed with a chemical composition consisting of carbon, silicon, manganese, phosphorous, sulfur, copper, chromium, nickel, and aluminum.
