API 5CT L80 9Cr Casing And Tubing Pipe
L80-9Cr is a steel grade under API 5CT, the international standard for casing and tubing in the oil and gas industry. It belongs to the L80 series and is specially engineered for resistance to CO₂ corrosion.
API 5CT: The primary specification governing the manufacture and testing of oilfield tubulars.
L80: Indicates a minimum yield strength of 80 ksi (~552 MPa).
9Cr: Denotes approximately 9% chromium content, which significantly enhances resistance to carbon dioxide (CO₂) corrosion.
This material is primarily used in high-CO₂ partial pressure or CO₂ + chloride co-existing acidic environments, effectively extending well life and reducing maintenance costs.
Strong resistance to CO ₂ corrosion! API 5CT L80 9CR oil casing, the "protective armor" for acidic oil and gas wells, click to get exclusive quotation!
L80-9Cr Color Band Identification Table
| Grade | Color Bands (Two Parallel Stripes) | Location |
|---|---|---|
| L80-9Cr | White + Green | On coupling or both ends of pipe body |
| L80-1 | White + Red | Same as above |
| L80-13Cr | White + Brown | Same as above |
Chemical Composition for L80-9Cr Pipes
| Element | Requirement (wt%) | Function |
|---|---|---|
| C (Carbon) | ≤0.15% | Controls hardness and weldability, prevents embrittlement |
| Cr (Chromium) | 8–10% | Key corrosion-resistant element, forms passive film |
| Mo (Molybdenum) | 0.90–1.10% | Enhances high-temperature strength and pitting resistance |
| Mn (Manganese) | 0.3–0.6% | Strengthens matrix, improves hardenability |
| Si (Silicon) | ≤1.0% | Deoxidizer, increases strength |
| P (Phosphorus) | ≤0.020% | Harmful element, strictly controlled |
| S (Sulfur) | ≤0.010% | Causes hot cracking, low sulfur required |
| Ni (Nickel) | ≤0.50% | Improves toughness and corrosion resistance |
Mechanical Properties for L80-9Cr Pipes
| Property | Requirement | Test Condition |
|---|---|---|
| Yield Strength (YS) | 552–665 MPa | Per API 5CT range |
| Tensile Strength (TS) | ≥655 MPa | Minimum value |
| Elongation (A) | ≥17.5% | Gauge length 50 mm |
| Impact Energy (0°C) | Transverse ≥31J, Longitudinal ≥68J | Charpy V-notch |
| Hardness | ≤23 HRC or ≤241 HB | Prevents hydrogen-induced cracking |
Heat Treatment Methods for L80-9Cr Pipes
Heat treatment is critical to achieving desired mechanical and corrosion-resistant properties. The standard process is quenching and tempering (Q&T):
- Normalizing
Temperature: 750–850°C
Purpose: Refine grain structure and homogenize microstructure
- Quenching
Heat to 650–750°C, then rapidly cool (oil or liquid nitrogen)
Forms martensite, increasing strength and hardness
- Tempering
Reheat to 650–750°C, hold for 1.5–2 hours, then cool
Relieves internal stress, improves toughness, stabilizes tempered martensite
Inspection for L80-9Cr Casing and Tubing
| Test Type | Inspection Items | Reference Standard |
|---|---|---|
| Chemical Analysis | Verify content of C, Cr, Mo, Mn, etc. | GB/T 19830, API 5CT |
| Tensile Test | Yield strength, tensile strength, elongation | API 5CT |
| Impact Test | Transverse ≥31J, longitudinal ≥68J at 0°C | API 5CT |
| Hardness Test | ≤23 HRC or ≤241 HB | API 5CT |
| Non-Destructive Testing (NDT) | Ultrasonic (UT), eddy current (ET) for internal flaws | API 5CT |
| Hydrostatic Test | Pressurized and held without leakage | API 5CT |
| Metallographic Analysis | Confirm tempered martensite structure, acceptable grain size | Internal standards |
Connection Types, Ends, and Couplings for L80-9Cr Pipes
| Item | Description |
|---|---|
| Connection Types | - Short Round Thread (STC): For shallow wells - Long Round Thread (LTC): Commonly used, good sealing - Premium Thread (e.g., VAM, Hydril): Metal-to-metal seal, high-pressure resistance, excellent bending resistance |
| End Finishing | Threaded ends cold-rolled to enhance fatigue strength |
| Couplings | Made from L80-grade steel; phosphated or copper-plated for lubrication and corrosion protection |
| Sealing Structure | Premium connections often feature metal-to-metal seals or elastomer seals for leak-proof performance under high pressure |
API 5CT L80 9Cr OCTG test and inspection
API 5CT L80 9CR Oil Casing Factory
FAQ
What is the difference between L80-1, L80 9Cr, and L80 13Cr in API 5CT
L80-1: Made of ordinary carbon steel with low alloy element content and no special corrosion resistance, suitable for conventional oil and gas wells with low corrosiveness and simple geological conditions.
L80-9Cr: containing about 9% chromium (Cr), significantly improving the resistance to carbon dioxide (CO ₂) corrosion, suitable for moderate corrosive environments, such as oil and gas wells containing CO ₂ or CO ₂ coexisting with chloride ions.
L80-13Cr: containing 12-13.5% chromium and adding elements such as molybdenum and nickel, it has excellent resistance to CO ₂, H ₂ S, and chloride ion corrosion, suitable for extreme corrosive environments such as high sulfur, high CO ₂, and deep sea
Are L80 9Cr available as welded pipe
According to the API 5CT standard, L80-9Cr is usually not available in welded pipe form and is only supplied in seamless pipe form.
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