API 5CT L80 Oil Special Pipe
API 5CT L80 Oil Special Pipe - Comprehensive Material Properties & Global Equivalents
Complete technical data for API 5CT L80 oil special pipe, including chemical composition, mechanical and thermal properties, international equivalents, and application guide.
Hot rolling, quench and temper, cold drawing, welding (with caution), threading, heat treatment
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API 5CT L80 Oil Special Pipe Introduction
API 5CT L80 is a widely used steel grade for oil country tubular goods (OCTG), specifically designed for casing and tubing in sour service and moderate to high-pressure oil & gas wells. It belongs to the group of quenched and tempered carbon-manganese or low-alloy steels. L80 exhibits a controlled yield strength range of 80 ksi to 95 ksi (552–655 MPa), ensuring reliable collapse resistance and sulfide stress cracking (SSC) resistance in H₂S environments when properly processed. The grade is available in several types, with Type 1 being the standard carbon steel version. Its excellent combination of strength, toughness, and corrosion resistance makes it a preferred choice for well completion and production operations.
API 5CT L80 Oil Special Pipe Chemical Composition
The chemical limits for API 5CT L80 Type 1 are broad to allow different manufacturing routes while ensuring mechanical properties and sour service compliance. The typical ladle analysis values listed below reflect common practice for Cr-Mo low-alloy steel that meets the strength and NACE MR0175 hardness criteria. Sulfur and phosphorus are strictly controlled for resistance to sulfide stress cracking.
| Element | Standard Value (max, wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.43 | Typical range 0.15–0.22 in fine practice |
| Manganese (Mn) | ≤1.90 | Adjust for strength; typical 0.80–1.20 |
| Silicon (Si) | ≤0.45 | Deoxidizer |
| Phosphorus (P) | ≤0.030 | Low P for toughness and SSC resistance |
| Sulfur (S) | ≤0.030 | Low S; often ≤0.005 for sour service |
| Chromium (Cr) | ≤1.50 | Typical 0.40–0.80 |
| Nickel (Ni) | ≤0.99 | Residual; no intentional addition |
| Molybdenum (Mo) | ≤0.75 | Typical 0.15–0.25 |
| Copper (Cu) | ≤0.35 | Residual; may be lower |
| Iron (Fe) | Balance | Remaining element |
API 5CT L80 Oil Special Pipe Thermal and Electrical Physical Properties
These values are representative for a quenched and tempered low-alloy steel similar to AISI 4130/4140 type, which covers most L80 Type 1 chemistries. Actual properties may vary slightly with specific heat treatment. Data derived from standard references for Cr-Mo steels at room temperature unless noted.
| Property | Typical Value | Unit | Test Condition / Notes |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Elastic Modulus (E) | 205 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Calculated |
| Poisson's Ratio (ν) | 0.29 | - | Room temperature |
| Thermal Expansion Coefficient (α) | 11.5 × 10⁻⁶ | 1/K | 20–100°C; increases at higher temperature |
| Thermal Conductivity (λ) | 42.6 | W/(m·K) | At 100°C |
| Specific Heat Capacity | 460 | J/(kg·K) | Room temperature |
| Electrical Resistivity (ρ_e) | 0.22 × 10⁻⁶ | Ω·m | Room temperature |
API 5CT L80 Oil Special Pipe Mechanical Properties
Minimum tensile requirements are specified by API 5CT. Values are obtained from quenched and tempered longitudinal specimens from the pipe body. For sour service, hardness control is essential; maximum hardness 23 HRC (or 241 HBW) is generally required per NACE MR0175. Charpy impact energy is often mandated by end users for low-temperature toughness.
| Property | Standard Requirement | Unit | Test Condition / Notes |
|---|---|---|---|
| Yield Strength (ReH) | 552 – 655 | MPa | 0.5% total extension under load; 80–95 ksi |
| Tensile Strength (Rm) | ≥655 | MPa | 95 ksi minimum |
| Elongation (A) | ≥e = 625000 A^0.2 / U^0.9 (min. strain) | % | Per API 5CT formula; e.g., typical 20–25% in 2-inch gauge |
| Hardness (HRC / HBW) | ≤23 HRC / ≤241 HBW | - | Required for sour service (NACE MR0175) |
| Charpy Impact (KV) | ≥27 (often specified) | J | At 0°C or lower; depends on supplementary spec |
API 5CT L80 Oil Special Pipe Fully Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | ISO 11960:2020 | L80 Type 1 | Identical to API 5CT |
| Russia / CIS | GOST 632-80 | 32G2 (32Г2) | Sour service casing with similar strength; requires verification |
| China | GB/T 19830-2017 (eqv. API 5CT) | L80 | Chinese adoption of API 5CT L80 |
| Europe | EN ISO 11960 | L80 Type 1 | European normative version; full compatibility |
API 5CT L80 Oil Special Pipe Application Introduction
API 5CT L80 casings and tubings are integral components in well construction, especially in sour service environments (H₂S-containing) and moderate-depth wells. They are suitable for both onshore and offshore oil and gas production and can be used in injection wells. The material's quenched and tempered microstructure ensures high dimensional stability during threading and make-up of premium connections.
Product Applications: Casing strings (surface, intermediate, production), Tubing strings (production tubing), Liner hangers and accessories, Pup joints and crossovers
Processed into products: Threaded pipe body (API round, buttress, premium connections), Couplings and integral joint connections, Seamless heavy-wall tubes for perforated liners, Upset tubing (external upset end)
Application industries: Upstream oil & gas exploration and production, Geothermal energy development, Gas storage and injection wells, Mining and water wells (when corrosion resistance is needed)
API 5CT L80 Oil Special Pipe Similar / Alternative Materials for Comparison
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | API 5CT | P110 | Higher strength (110 ksi min yield); not directly interchangeable; use for non-sour deeper wells where collapse resistance is primary |
| USA | API 5CT | C95 | Yield 95–110 ksi; alternative in some intermediate casings |
| USA | API 5CT | L80 9Cr / 13Cr | Higher corrosion resistance for CO₂; different chemistry but same strength group |
| International | ISO 11960 | L80 9Cr / 13Cr | See above |
| China | GB/T 19830 | BG80S | Similar sour service casing steel |
Notes:
Sour service compliance: L80 Type 1 is generally accepted under NACE MR0175/ISO 15156 for region 3 (high H₂S) when hardness ≤23 HRC and with controlled residual stresses. Supplementary testing such as Charpy impact at low temperatures (e.g., -46°C) and sulfide stress cracking (SSC) tests may be required by project specifications. Always refer to the specific API 5CT edition and customer requirements for supplementary requirements (e.g., PSL-2, PSL-3). The data provided are for general reference and typical production; actual certified mill test values should prevail.
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