API 5L PSL2 X42 ERW Steel Pipe
Basic Overview
API 5L PSL2 Grade X42 ERW (Electric Resistance Welded) steel pipe is a medium-strength line pipe that combines the enhanced quality requirements of PSL2 with the X42 strength grade. The "X42" designation indicates a minimum yield strength of 42,000 psi (290 MPa) , while PSL2 mandates stricter chemical controls, mandatory impact testing, maximum strength limits, and full traceability .
The designation breaks down as follows:
API 5L: American Petroleum Institute specification for line pipe
PSL2: Product Specification Level 2 (enhanced quality with mandatory testing)
X42: Grade indicating minimum yield strength of 42 ksi (290 MPa)
ERW: Electric Resistance Welded – pipe formed from steel coil and welded longitudinally without filler metal
Key Specifications
| Parameter | Specification |
|---|---|
| Standard | API 5L (46th Edition, aligned with ISO 3183) |
| Product Specification Level | PSL2 |
| Grade | X42 (L290 in ISO notation) |
| Minimum Yield Strength | 290 MPa (42,100 psi) |
| Maximum Yield Strength | 496 MPa (72,000 psi) – PSL2 specifies both min and max |
| Minimum Tensile Strength | 414 MPa (60,200 psi) |
| Maximum Tensile Strength | 758 MPa (110,000 psi) |
| Yield-to-Tensile Ratio (max) | 0.93 |
| Manufacturing Type | ERW (Electric Resistance Welded) / HFW |
| Size Range (ERW) | 1/2" to 26" (21.3 mm to 660 mm) OD; typical ERW up to 24" |
| Wall Thickness | Schedule 10 to 160, STD, XS; up to 22.2 mm |
| Length | 5 m to 14 m; SRL, DRL; 5.8 m, 6 m, 11.8 m, 12 m standard |
| End Finishes | Plain ends, beveled ends |
Chemical Composition (PSL2 Welded Pipe)
| Element | Maximum % | PSL1 Comparison |
|---|---|---|
| Carbon (C) | 0.22% | 0.26% (tighter control) |
| Manganese (Mn) | 1.40% | 1.30% (higher for strength) |
| Phosphorus (P) | 0.025% | 0.030% (stricter) |
| Sulfur (S) | 0.015% | 0.030% (50% reduction) |
| Silicon (Si) | 0.40-0.45% | Not specified for PSL1 |
| Vanadium (V) | ≤0.06% | Optional |
| Niobium (Nb) | ≤0.05% | Optional |
| Titanium (Ti) | ≤0.04% | Optional |
Note: PSL2 also requires carbon equivalent (CE) calculation and control .
Mechanical Properties
| Property | PSL2 Requirement | PSL1 Comparison |
|---|---|---|
| Yield Strength (min) | 290 MPa (42,100 psi) | Same minimum |
| Yield Strength (max) | 496 MPa (72,000 psi) | Not specified |
| Tensile Strength (min) | 414 MPa (60,200 psi) | Same minimum |
| Tensile Strength (max) | 758 MPa (110,000 psi) | Not specified |
| Yield-to-Tensile Ratio | 0.93 max | Not specified |
| Elongation | Per API 5L formula | Same formula |
| Charpy Impact (CVN) | Mandatory at specified temperature | Not required |
Dimensional Tolerances (API 5L)
| Parameter | Size Range | Tolerance | Source |
|---|---|---|---|
| Pipe Body OD | 219.1～457 mm | ±0.75% | |
| Pipe Body OD | 508～610 mm | ±0.75% | |
| Pipe Ends (219.1-273.1 mm) | - | +1.6 mm / -0.4 mm | |
| Pipe Ends (274-320 mm) | - | +2.4 mm / -0.8 mm | |
| Pipe Ends (323.9-457 mm) | - | +2.4 mm / -0.8 mm | |
| Wall Thickness (508-610 mm) | - | +19.5% / -8% | |
| Wall Thickness (219.1-457 mm) | - | +15% / -12.5% |
ERW Manufacturing Process
ERW steel pipe is a straight seam electric resistance welded pipe produced through a continuous process :
Uncoiling – Steel coil is uncoiled and leveled
Edge Preparation – Strip edges are milled for proper welding
Forming – Steel strip is cold-formed into cylindrical shape
Electric Induction Welding – High-frequency welding joins edges without filler metal
Heat Treatment – The weld seam is normalized to refine grain structure
Sizing – Pipe passes through sizing rolls to achieve final dimensions
NDT – 100% non-destructive testing (ultrasonic or eddy current) of weld seam
Hydrostatic Testing – Each pipe individually tested for pressure integrity
End Finishing – Ends prepared (plain or beveled)
Testing Requirements (PSL2)
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Tighter PSL2 limits |
| Tensile Test | Per lot | Verifies both min and max limits |
| Yield-to-Tensile Ratio | ≤ 0.93 | Mandatory verification |
| Charpy Impact Test (CVN) | Mandatory | 27 J minimum at specified temperature (often 0°C or -20°C) |
| Flattening Test | Required for ERW pipe | Checks ductility |
| Bend Test | Required | Verifies weld integrity |
| Hydrostatic Test | Each pipe | Pressure integrity verification |
| NDT (Ultrasonic/Eddy Current) | 100% of weld seam | Mandatory for PSL2 |
| Hardness Testing | For sour service | Hardness mapping required when specified |
Grade Comparison: X42 vs. Adjacent Grades
| Grade | Yield Strength (min) | Tensile Strength (min) | Relative Strength vs. X42 | Typical Application |
|---|---|---|---|---|
| B | 241 MPa (35 ksi) | 414 MPa (60 ksi) | -17% | Low-pressure gathering, utilities |
| X42 | 290 MPa (42 ksi) | 414 MPa (60 ksi) | Baseline | Medium-pressure transmission |
| X46 | 320 MPa (46 ksi) | 435 MPa (63 ksi) | +10% | Higher-pressure transmission |
| X52 | 359 MPa (52 ksi) | 455 MPa (66 ksi) | +24% | General transmission |
X42 offers approximately 17% higher yield strength than Grade B .
PSL1 vs. PSL2 Comparison for X42
| Feature | PSL1 X42 | PSL2 X42 | Significance |
|---|---|---|---|
| Carbon (C) max | 0.26-0.28% | 0.22% | Better weldability, lower HAZ hardness |
| Sulfur (S) max | 0.030% | 0.015% | 50% reduction – critical for toughness and HIC resistance |
| Phosphorus (P) max | 0.030% | 0.025% | Improved toughness and weldability |
| Manganese (Mn) max | 1.30% | 1.40% | Slightly higher for strength |
| Yield Strength | 290 MPa min only | 290-496 MPa range | Prevents over-strength materials |
| Tensile Strength | 414 MPa min only | 414-758 MPa range | Ensures consistent mechanical properties |
| Yield-to-Tensile Ratio | Not specified | ≤ 0.93 | Ensures adequate ductility |
| Charpy Impact Testing | Not required | Mandatory (27J at 0°C or -20°C) | Guarantees low-temperature toughness |
| Carbon Equivalent (CE) | Not required | Calculated and controlled | Ensures good field weldability |
| NDT Requirements | Standard | More stringent | Better defect detection |
| Traceability | Batch level | Pipe-by-pipe full traceability | Complete quality documentation |
| Typical Use | General service | Critical service, low temperature, regulated pipelines |
Common Applications
| Application | Description |
|---|---|
| Oil and Gas Transmission | Medium-pressure pipelines for crude oil and natural gas |
| Natural Gas Gathering Lines | Connecting wells to processing facilities; Class II/III onshore gas transmission |
| Water Transmission Mains | Large-diameter municipal and industrial water pipelines |
| Sour Service | H₂S environments (with supplementary requirements) |
| Low-Temperature Service | Applications requiring guaranteed impact toughness at -20°C |
| Industrial Process Piping | Refineries, chemical plants, power engineering |
| Pipeline Station and Terminal Piping | Compressor stations, pump stations, metering facilities |
| Offshore Pipelines | Subsea applications with enhanced toughness requirements |
Key Advantages
| Advantage | Description |
|---|---|
| Guaranteed Toughness | Mandatory Charpy impact testing (≥27J) ensures low-temperature performance; X42 PSL2 maintains impact energy >27J even at -20°C |
| Stricter Chemistry | 50% lower sulfur content (0.015% vs. 0.030%) improves weldability and HIC resistance |
| Controlled Strength | Maximum yield strength (496 MPa) prevents over-strength materials that can cause welding issues |
| Full Traceability | Pipe-by-pipe traceability for complete quality documentation |
| Enhanced NDT | More stringent non-destructive testing requirements |
| Cost-Effective | ERW process provides economical production for sizes up to 24" |
| Micro-Alloyed | Mandatory addition of Nb/V microalloying elements for improved properties |
Important Considerations
1. Size Limitations
ERW manufacturing for X42 is typically available up to 24-26 inches (610 mm) OD
Larger diameters require LSAW or SSAW manufacturing
2. PSL1 vs. PSL2 Selection
PSL2: Required for low-temperature service (especially below 0°C), sour service (H₂S environments), regulated pipelines (FERC, DOT), and critical applications
PSL1: Suitable for general service, water lines, non-critical applications where low-temperature toughness is not required
3. Impact Testing Temperature
Standard Charpy impact testing is at 0°C with 27J minimum
For colder applications, impact testing at -20°C with 27J minimum can be specified
4. Equivalent Grades
ISO 3183: L290
GB/T 9711: L290
EN 10208-2: L290NB
ASTM A106: Grade B (seamless, similar strength but different standard)
ASTM A53: Grade B (similar strength but different standard)
5. Coating Options
FBE (Fusion Bonded Epoxy): Corrosion protection for buried pipelines
3LPE (3-layer polyethylene): Most common for buried pipelines
Black (bare): Standard mill finish
Varnish/Anti-rust oil: Temporary protection during transport
6. Mill Test Certificate
Typically provided as EN 10204 Type 3.1 with full test results
Third-party inspection (SGS, BV, Lloyds) available upon request
7. X42 vs. Grade B
X42 offers approximately 17% higher yield strength than Grade B, making it a cost-effective upgrade for medium-pressure transmission applications. In sour gas or low-temperature environments, X42 PSL2 is more economical over the lifecycle due to its enhanced toughness and corrosion resistance .
Summary
API 5L PSL2 Grade X42 ERW steel pipe is a medium-strength line pipe that combines the X42 strength grade (290 MPa minimum yield) with the enhanced PSL2 quality requirements. With stricter chemical controls (S ≤ 0.015%, P ≤ 0.025%), mandatory Charpy impact testing (≥27J at 0°C or -20°C), maximum strength limits (≤ 496 MPa yield), yield-to-tensile ratio control (≤ 0.93), and full pipe-by-pipe traceability, PSL2 X42 is the preferred choice for medium-pressure transmission applications requiring guaranteed low-temperature toughness or sour service capability .
Key features:
Available in PSL2 quality level with enhanced testing requirements
Manufactured by ERW process – sizes from 1/2" to 24" OD
Mandatory Charpy impact testing (27J minimum) ensures low-temperature performance
50% lower sulfur content (0.015% vs. 0.030%) improves toughness and HIC resistance
Maximum yield strength (496 MPa) prevents over-strength materials
Micro-alloyed with Nb/V for enhanced properties
Full traceability from steelmaking to finished pipe
Common applications include:
Medium-pressure oil and gas transmission pipelines
Natural gas gathering and distribution networks
Low-temperature service requiring guaranteed impact toughness
Regulated pipelines under FERC, DOT, or other authorities
Sour service applications (with supplementary requirements)
When ordering, specify: API 5L PSL2 Grade X42 ERW steel pipe, Size (OD x WT), Length, End Finish (plain/beveled), Heat Treatment Condition (if required), Coating Requirements (FBE/3LPE/bare), and any supplementary requirements (impact test temperature, sour service). Mill Test Certificate to EN 10204 Type 3.1 is standard .
