L80 (L80-1) Oil Country Tubular Goods Steel Grade
L80 (L80-1) Oil Country Tubular Goods Steel Grade - API 5CT Casing & Tubing
Comprehensive material data for L80 (L80-1) steel grade per API 5CT, including chemical composition, mechanical and physical properties, international equivalents, and similar grades like M65.
Hot rolling, heat treatment (quench & temper), threading, cold drawing (for couplings)
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L80 Oil Country Tubular Goods Steel Grade Introduction
L80 (L80-1) is an API 5CT steel grade widely used for oil country tubular goods (OCTG) in casing and tubing applications. It is a quenched-and-tempered, medium-carbon manganese steel designed for sour service (H₂S resistance) when tested in accordance with NACE MR0175. Key characteristics include controlled yield strength range (552–655 MPa), good toughness, and restricted hardness (max 23 HRC for L80-1). The M65 grade, also per API 5CT, is a lower-strength alternative (yield 448–586 MPa) often used in less demanding environments. This datasheet focuses on L80-1; details on M65 are provided in similar materials section.
L80 Oil Country Tubular Goods Steel Grade Chemical Composition
Composition limits for L80-1 per API 5CT, 11th Ed., Tables C.3 & C.4. Elements not listed have no specified maximum unless required by deoxidation practice. Carbon equivalent (CE) is typically controlled to ensure adequate weldability (CEₑ ≤ 0.43 where applicable).
| Element | Specified Value (max, %) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.43 | Product analysis can be slightly higher |
| Manganese (Mn) | ≤ 1.90 | Typical range 1.30–1.70 for L80-1 |
| Phosphorus (P) | ≤ 0.020 | For product analysis: ≤ 0.025 |
| Sulfur (S) | ≤ 0.010 | For product analysis: ≤ 0.015 |
| Silicon (Si) | ≤ 0.45 | Required for deoxidation |
| Chromium (Cr) | ≤ 0.40 | Residual or intentional addition |
| Molybdenum (Mo) | ≤ 0.21 | May be added for hardenability |
| Nickel (Ni) | ≤ 0.25 | Residual element |
| Copper (Cu) | ≤ 0.35 | Residual; can be controlled for certain orders |
| Vanadium (V) | ≤ 0.15* | *Sum of V+Nb+Ti ≤ 0.15% |
| Niobium (Nb) | ≤ 0.15* | *Sum of V+Nb+Ti ≤ 0.15% |
| Titanium (Ti) | ≤ 0.15* | *Sum of V+Nb+Ti ≤ 0.15% |
| Boron (B) | ≤ 0.001 | If intentionally added, specified by purchaser |
| Aluminum (Al) | Report only | Used for grain refinement (typically 0.01–0.04%) |
L80 Oil Country Tubular Goods Steel Grade Thermal and Electrical Physical Properties
Physical properties are typical for medium‑carbon, low‑alloy quenched‑and‑tempered steel, not specifically mandated by API 5CT. Data provided for design purposes at room temperature unless noted.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Ambient temperature |
| Modulus of Elasticity (E) | 205 | GPa | Tension, ambient temperature |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν |
| Poisson´s Ratio (ν) | 0.29 | – | Ambient temperature |
| Thermal Expansion Coefficient (α) | 11.7 (20–100 °C), 12.3 (20–200 °C), 13.0 (20–300 °C) | 10⁻⁶ /K | Linear expansion; typical range |
| Thermal Conductivity (λ) | 42 | W/(m·K) | At 20 °C; decreases with temperature |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρe) | 0.25 | µΩ·m | At 20 °C |
L80 Oil Country Tubular Goods Steel Grade Mechanical Properties
Mechanical properties required by API 5CT for L80-1 pipe body (tested at ambient temperature). Hardness limits are critical for sour service compliance. Values apply to wall thickness ≤ 1.000 inch (25.4 mm) unless otherwise noted. For thicker walls, properties are subject to agreement.
| Property | Specified Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Yield Strength (ReH) | 552 – 655 | MPa | 0.2% offset, longitudinal or transverse specimen |
| Tensile Strength (Rm) | ≥ 655 | MPa | Minimum ultimate tensile |
| Elongation (A) | See formula | % | A = 625000 * (Ax / U)⁰·², min 13%. Ax = cross-sectional area, U = tensile strength (psi) |
| Hardness (Base Metal) | ≤ 23 HRC or ≤ 255 HBW | — | Maximum to resist sulfide stress cracking |
| Hardness (Weld Zone) | ≤ 23 HRC or ≤ 255 HBW | — | If welded, also apply to HAZ |
| Impact Toughness (KV) | Optional, as agreed | J | Typical Charpy V-notch @ 0°C requires ≥ 20 J average |
| Bend Test | No cracking | — | Full-section or strip specimens, 180° bend, diameter ≤ 3t (t = thickness) |
L80 Oil Country Tubular Goods Steel Grade Completely Equivalent Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Global | ISO 11960 | L80-1 | Identical chemical & mechanical requirements |
| China | GB/T 19830 | L80-1 | Equivalent to API 5CT L80-1 |
| Ukraine | DSTU 7374 | L80-1 | Harmonized with API 5CT |
| Russia | GOST R 53366 | L-80 (type 1) | Interchangeable; may require supplementary testing |
| Europe | EN ISO 11960 | L80-1 | Adopted as European standard |
L80 Oil Country Tubular Goods Steel Grade Application Introduction
L80-1 is the workhorse grade for sour (H₂S) well casing and tubing. It complies with NACE MR0175 / ISO 15156 for region 1, 2, and 3 environments. M65 may be selected for non‑sour or mildly corrosive wells where lower strength suffices.
Key applications include:
Product Applications: Seamless casing pipes for wellbore structural support, Tubing strings for hydrocarbon production, Liner hanger bodies and accessories, Drill pipe (in non‑critical applications), Pup joints and cross‑overs
Processed into products: Pipe body (casing and tubing), Integral and threaded & coupled connections (e.g., API BTC, LTC, premium connections), Couplings (manufactured from same grade or higher strength steel), Blast joints and flow couplings (severely cold‑worked, requiring careful hardness control), Perforating gun carriers (some designs utilize L80 tubulars), Gas lift mandrels and side pocket mandrels (material selection based on well conditions)
Application industries: Onshore & offshore oil & gas exploration and production, Geothermal well construction, CO₂ sequestration wells (with appropriate corrosion assessment), Workover and completion operations
L80 Oil Country Tubular Goods Steel Grade Recommendations for Near-Similar / Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Global | API 5CT | M65 | Lower strength (yield 448–586 MPa), used in less demanding service; not always certified for sour service |
| Global | API 5CT | N80-1/N80-Q | N80-1 similar chemistry but higher strength (552–758 MPa); N80-Q also Q&T; check H2S resistance |
| Global | API 5CT | C90 | Higher strength (621–724 MPa) with controlled hardness for sour service; more expensive |
| China | GB/T 19830 | L80-9Cr / L80-13Cr | Similar strength but with 9% or 13% Cr for CO₂ corrosion resistance |
| Global | ISO 11960 | L80-9Cr / L80-13Cr | As above; not directly interchangeable with L80-1 due to alloy content |
Notes:
L80 M65 oil special pipe may refer to a dual‑certified product or a contractual requirement that combines both grades – consult the specific material certificate. M65 is an API 5CT grade with min. yield 448 MPa and max. 586 MPa; it is not inherently sour‑service rated unless tested per NACE MR0175. Always verify with the manufacturer if the pipe has been ordered as L80 with M65 supplementary specifications (e.g., restricted yield range). Additionally, for welding of L80, preheat and PWHT may be required to maintain hardness below 250 HV10 in the HAZ.
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