API 5L PSL1 X42 ERW Steel Pipe
Basic Overview
API 5L PSL1 Grade X42 ERW (Electric Resistance Welded) steel pipe is a medium-strength carbon steel line pipe widely used in oil and gas transmission systems . The "X42" designation indicates a minimum yield strength of 42,000 psi (290 MPa) , representing a significant strength increase over Grade B .
The designation breaks down as follows:
API 5L: American Petroleum Institute specification for line pipe
PSL1: Product Specification Level 1 (standard quality level with basic requirements)
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 | PSL1 |
| Grade | X42 (L290 in ISO notation) |
| Minimum Yield Strength | 290 MPa (42,000 psi) |
| Minimum Tensile Strength | 415 MPa (60,000 psi) |
| Manufacturing Type | ERW (Electric Resistance Welded) |
| Size Range (OD) | 21.3 mm to 660 mm (1/2" to 26") |
| Wall Thickness | 1.0 mm to 22.2 mm |
| Length | 3 m to 22 m (standard: 5.8/6/11.8/12 m, SRL, DRL) |
| End Finishes | Plain ends, beveled ends, threaded ends |
Chemical Composition (PSL1 Welded Pipe)
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.26% | Lower than seamless grade (0.28%) for better weldability |
| Manganese (Mn) | 1.30% | Provides strength |
| Phosphorus (P) | 0.030% | Controlled for weldability |
| Sulfur (S) | 0.030% | Controlled for toughness |
| Silicon (Si) | 0.40% | Deoxidizer |
Note: For each reduction of 0.01% below the specified maximum carbon content, an increase of 0.05% above the specified maximum manganese is permitted, up to a maximum of 1.65% .
Mechanical Properties (PSL1)
| Property | Requirement |
|---|---|
| Yield Strength (min) | 290 MPa (42,000 psi) |
| Tensile Strength (min) | 415 MPa (60,000 psi) |
| Elongation | 28% minimum |
Dimensional Tolerances
| Parameter | Size Range | Tolerance |
|---|---|---|
| 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% |
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% | General pipeline service |
| X42 | 290 MPa (42 ksi) | 415 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 .
Testing Requirements (PSL1)
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Verifies composition limits |
| Tensile Test | Per lot | Verifies yield and tensile strength |
| Flattening Test | Required for ERW pipe | Checks ductility |
| Bend Test | Required | Verifies weld integrity |
| Hydrostatic Test | Each pipe individually tested | Pressure integrity verification |
| NDT (Ultrasonic/Eddy Current) | Weld seam inspection | Standard practice |
| Impact Testing (Charpy V-notch) | Not required for PSL1 | Only PSL2 requires mandatory impact testing |
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 – Medium frequency heat treatment normalizes the weld zone
Sizing – Pipe passes through sizing rolls to achieve final dimensions
NDT – Ultrasonic detection of weld seam
Hydrostatic Testing – Each pipe individually tested for pressure integrity
End Finishing – Ends prepared (plain, beveled, or threaded)
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 |
| Water Transmission Mains | Large-diameter municipal and industrial water pipelines |
| Industrial Process Piping | Refineries, chemical plants, power generation |
| Gathering and Flow Lines | Upstream oil and gas operations |
| Structural Applications | Piling, bridge supports, construction |
PSL1 vs. PSL2 Comparison for X42
| Feature | PSL1 | PSL2 | Significance |
|---|---|---|---|
| Carbon (C) max | 0.26% | 0.24% | Better weldability |
| Sulfur (S) max | 0.030% | 0.015% | 50% reduction – improved toughness |
| Yield Strength | Min only (290 MPa) | Min and Max (290-496 MPa) | Prevents over-strength materials |
| Yield-to-Tensile Ratio | Not specified | ≤ 0.93 max | Ensures adequate ductility |
| Impact Testing | Not required | Mandatory | Guarantees low-temperature toughness |
| NDT Requirements | Standard | More stringent | Better defect detection |
| Typical Use | General service | Critical service, low-temperature applications |
Key Advantages
| Advantage | Description |
|---|---|
| Higher Strength than Grade B | 17% higher yield strength allows higher operating pressures or reduced wall thickness |
| Cost-Effective | ERW process provides economical production for sizes up to 24" |
| Excellent Weldability | Controlled chemistry ensures good field weldability |
| Wide Availability | Commonly stocked by manufacturers globally |
| Dual Certification | Often dual-certified with other standards for general piping applications |
Important Considerations
1. Size Limitations
ERW manufacturing is typically limited to 24-26 inches (610 mm) OD
Larger diameters require LSAW or SSAW manufacturing
2. PSL1 vs. PSL2 Selection
PSL1: Suitable for general service, water lines, non-critical applications
PSL2: Required for low-temperature service, sour service (H₂S environments), regulated pipelines (FERC, DOT), and critical applications
3. Equivalent Grades
ISO 3183: L290
GB/T 9711: L290
ASTM A53: Grade B (similar strength level)
4. Coating Options
Black (bare): Standard mill finish
FBE (Fusion Bonded Epoxy): Corrosion protection for buried pipelines
3LPE (3-layer polyethylene): For buried applications
Varnish/Anti-rust oil: Temporary protection during transport
5. Mill Test Certificate
Typically provided as EN 10204 Type 3.1B with full test results
Third-party inspection (SGS, BV, Lloyds) available upon request
Summary
API 5L PSL1 Grade X42 ERW steel pipe is a medium-strength line pipe widely used in oil and gas transmission systems . With minimum yield strength of 42,000 psi (290 MPa) – approximately 17% higher than Grade B – it offers an excellent balance of strength and cost-effectiveness for medium-pressure pipeline applications .
Key features:
Available in PSL1 quality level for general service applications
Manufactured by ERW process – sizes from 1/2" to 26" OD
28% minimum elongation provides good ductility
No mandatory impact testing – suitable for ambient temperature applications
Cost-effective upgrade from Grade B for medium-pressure transmission
Common applications include:
Medium-pressure oil and gas transmission pipelines
Natural gas gathering and distribution networks
Water transmission mains and industrial process piping
Structural applications such as piling and bridge supports
When ordering, specify: API 5L PSL1 Grade X42 ERW steel pipe, Size (OD x WT), Length, End Finish, and Coating Requirements. For applications requiring guaranteed low-temperature toughness or sour service resistance, specify API 5L PSL2 Grade X42 instead .
