API 5L PSL2 X56N (L390N) Pipeline Steel Coil
API 5L PSL2 X56N (L390N) Pipeline Steel Coil - Properties, Equivalents & Applications
Technical data sheet for API 5L PSL2 X56N (L390N) pipeline steel coil: chemical composition, mechanical and physical properties, international equivalent grades, and application guidance.
Hot rolling, normalizing, welding (for pipe production), cold forming
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API 5L PSL2 X56N Pipeline Steel Coil Introduction
API 5L PSL2 X56N (L390N) is a normalized, high-strength low-alloy (HSLA) pipeline steel supplied in coil form. It meets the requirements of PSL2 under API Specification 5L, offering enhanced toughness, improved weldability, and stringent controls on sulfur and phosphorus. The grade is also designated as L390N according to ISO 3183. Typical characteristics include:
- Minimum yield strength of 390 MPa (56 ksi) and excellent impact toughness at low temperatures.
- Fine-grained microstructure achieved through normalizing, ensuring consistent mechanical properties.
- Good resistance to hydrogen-induced cracking (HIC) when supplementary testing is specified.
- Widely used for manufacturing longitudinally welded or spiral welded pipe for oil and gas transmission.
Delivery condition is normalized (N) with full traceability and strict carbon equivalent limits for field welding.
API 5L PSL2 X56N Pipeline Steel Coil Chemical Composition
Composition limits for API 5L PSL2 X56N (L390N) as specified in the standard. Values are maximum unless a range is shown. Carbon equivalent CEIIW ≤ 0.43 (when C > 0.12%) or ≤ 0.45 (when C ≤ 0.12%) applies for normalized material.
| Chemical Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | 0.22 max | – |
| Manganese (Mn) | 1.40 max | – |
| Silicon (Si) | 0.45 max | – |
| Phosphorus (P) | 0.025 max | PSL2 requirement |
| Sulfur (S) | 0.015 max | PSL2 requirement |
| Vanadium (V) | 0.05 max | – |
| Niobium (Nb) | 0.05 max | – |
| Titanium (Ti) | 0.04 max | – |
| V+Nb+Ti | 0.15 max | Sum of microalloying elements |
| Copper (Cu) | 0.50 max | – |
| Nickel (Ni) | 0.50 max | – |
| Chromium (Cr) | 0.50 max | – |
| Molybdenum (Mo) | 0.50 max | – |
| Nitrogen (N) | 0.012 max | – |
| Boron (B) | 0.0005 max | Residual element |
| Aluminum (Al) total | 0.060 max | Typically present as grain refiner |
| CEIIW | 0.43 max (C>0.12%) | Carbon equivalent – IIW formula |
API 5L PSL2 X56N Pipeline Steel Coil Thermal, Electrical and Physical Properties
Physical properties are representative for normalized HSLA pipeline steel similar to X56N. These values are not mandatory requirements but are commonly used for design and simulation purposes.
| Property | Standard Requirement Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Elastic Modulus (E) | 207 | GPa | Room temperature |
| Shear Modulus (G) | 80 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.30 | – | Room temperature |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 12.9 | 10⁻⁶/K | 20 – 300 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | Room temperature |
| Specific Heat Capacity (c) | 486 | J/(kg·K) | Room temperature |
| Electrical Resistivity (ρ_e) | 0.20 | 10⁻⁶ Ω·m | Room temperature |
API 5L PSL2 X56N Pipeline Steel Coil Mechanical Properties
Mechanical test results referenced from API 5L PSL2 for X56N (L390N) normalized condition. Actual values depend on wall thickness and specimen orientation. Charpy tests are performed on transverse, full-size specimens.
| Property | Standard Requirement Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (Rt0.5) | 390 – 545 | MPa | Transverse to pipe axis, room temperature |
| Tensile Strength (Rm) | 490 – 760 | MPa | Transverse to pipe axis, room temperature |
| Yield-to-Tensile Ratio (Rt0.5/Rm) | 0.93 max | – | PSL2 requirement |
| Elongation (A) | min. 22 (typical) | % | Transverse strip specimen, gauge length 50 mm, wall thickness ≤ 12.7 mm; actual value per formula Af = 1500·Axc0.2/Rm0.9 |
| Bend Test (180°) | No cracks | – | Bend mandrel diameter: 3× wall thickness (for Ductile materials) |
| Charpy V-notch Impact Energy (KV) | min. avg 27 | J | Transverse, full-size 10×10 mm, temperature 0 °C (base requirement) |
| Charpy V-notch Impact Energy (KV) | min. individual 20 | J | Transverse, full-size 10×10 mm, temperature 0 °C |
| Charpy V-notch Impact Energy (KV) | min. avg 40 (option) | J | When more stringent toughness is required, e.g. -20 °C testing |
API 5L PSL2 X56N Pipeline Steel Coil Exactly Equivalent Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | ISO 3183 (PSL2) | L390N | Normalized, fully interchangeable with API 5L X56N |
| Europe | EN 10208-2 | L390NB | Normalized; supplementary requirements may differ slightly |
| China | GB/T 9711 (PSL2) | L390N | Harmonized with ISO 3183, equivalent in mechanical and chemical properties |
| USA | API 5L (PSL2) | X56N | Original designation – normalized coil |
| Russia / CIS | ГОСТ Р 52079 (К52) | – | Steel strength class K52 may be supplied to L390N agreement |
API 5L PSL2 X56N Pipeline Steel Coil Application Introduction
API 5L PSL2 X56N coil is primarily converted into line pipe for the energy sector. Its normalized condition and fine-grain structure make it especially suitable for sour (wet H₂S) service when tested for HIC/SWC. The material is formable and weldable, allowing manufacture of a wide range of piping components.
Product Applications: ERW/HFW (electric resistance welded) line pipe, SAWL (longitudinal submerged arc welded) pipe, SAWH (spiral submerged arc welded) pipe, Coated line pipe (3LPE, FBE, etc.), Insulated line pipe for subsea applications
Processed into products: Pipe fittings (elbows, tees, reducers), Flanges and connectors, Pressure vessels and storage tank shells (when certified), Pipeline repair sleeves and casing pipes, Cold-formed structural hollow sections
Application industries: Oil & gas (upstream, midstream, downstream), Petrochemical and refining, Water transmission (high-pressure), Offshore structures (risers, flowlines), Mining slurry pipelines
API 5L PSL2 X56N Pipeline Steel Coil Similar / Substitute Grades with Close Performance
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | API 5L PSL2 | X56Q (L390Q) | Quenched & tempered; higher strength and lower toughness than normalized N grade, not a direct substitute for welding without evaluation |
| International | API 5L PSL2 | X56M (L390M) | Thermo-mechanically rolled; lower carbon equivalent, good toughness, can replace N in many applications but delivery condition differs |
| International | API 5L PSL1 | X56 | No PSL2 impact/sulfur restrictions; suitable for less demanding pipelines |
| Europe | EN 10208-2 | L390MB | TMCP steel with comparable strength, may be used with careful welding procedure |
| China | GB/T 9711 | L390 | PSL1 grade without mandatory normalization; lower cost, reduced toughness guarantees |
Notes:
Supplementary requirements often applied to this grade include HIC (Hydrogen Induced Cracking) test per NACE TM0284, SSC (Sulfide Stress Cracking) test for sour service, and drop weight tear test (DWTT) for fracture arrest. When ordering coil for line pipe, the purchaser should specify the intended pipe manufacturing process, required testing (e.g., Charpy temperature), and any special limits on carbon equivalent (Pcm) for field weldability. For the most accurate data, the specific mill certificate should be consulted.
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