API 5L Grade X65 PSL2 ERW Pipe
API 5L Grade X65 PSL2 ERW Pipe (Electric Resistance Welded) is a high-strength line pipe grade. It is manufactured by heating the edges of a steel coil using high-frequency current and then mechanically pressing them together to form a longitudinal weld.
X65 represents a minimum yield strength of 65,000 psi (450 MPa).
PSL2 indicates the pipe meets Product Specification Level 2, which includes mandatory impact toughness testing, stricter chemical composition control, and full heat traceability.
ERW (HFW) process offers advantages such as tight wall thickness tolerances, excellent roundness, and high production efficiency, making it ideal for medium-to-large diameter oil and gas gathering and distribution lines.
API 5L X65 PSL2 ERW Pipe Specification Table
| Item | Description |
| Standard | API Spec 5L (46th Ed. or later) |
| Grade | X65 / L450 |
| Product Specification Level | PSL 2 |
| Welding Type | ERW / HFW (Electric Resistance Welded / High-Frequency Welded) |
| Outer Diameter (OD) | 2 3/8" – 24" (60.3mm – 610mm) |
| Wall Thickness (WT) | 3.2mm – 22mm (Depends on OD) |
| End Finish | Beveled End (BE), Plain End (PE) |
| Length | Single Random (SRL), Double Random (DRL), Fixed Length |
API 5L X65 Material Properties and Chemical Composition
Mechanical Properties (API 5L X65 PSL2)
PSL2 specifies both minimum and maximum limits for yield and tensile strength.
| Property | Value (Grade X65 / L450 PSL2) |
| Yield Strength | 450 - 600 MPa (65,300 - 87,000 psi) |
| Tensile Strength | 535 - 760 MPa (77,600 - 110,200 psi) |
| Yield to Tensile Ratio | ≤ 0.93 |
| Toughness (Charpy V-notch) | Mandatory testing at 0°C |
Chemical Composition (API 5L X65 Max % - PSL2 Welded)
Carbon limits for welded pipes (ERW) are typically lower than seamless to improve weldability.
| Element | Content (Max %) |
| Carbon (C) | 0.22 |
| Manganese (Mn) | 1.45 |
| Phosphorus (P) | 0.025 |
| Sulfur (S) | 0.015 |
| Silicon (Si) | 0.45 |
| Carbon Equivalent (CEiiw) | ≤ 0.43 |
API 5L X65 Pipe Wall Thickness Table
Standard wall thicknesses (mm) for common NPS sizes per ASME B36.10:
| NPS | OD (mm) | SCH 20 | SCH 40 (STD) | SCH 80 (XS) |
| 6" | 168.3 | 4.78 | 7.11 | 10.97 |
| 8" | 219.1 | 6.35 | 8.18 | 12.70 |
| 12" | 323.8 | 6.35 | 10.31 | 12.70 |
| 16" | 406.4 | 7.92 | 12.70 | 12.70 |
| 24" | 610.0 | 9.53 | 12.70 | 12.70 |
API 5L Pipe Sizes and Tolerances Table
| Property | Nominal Diameter (D) | Tolerances |
| Outside Diameter (OD) | 60.3mm < D ≤ 610mm | ± 0.0075 D |
| Wall Thickness (WT) | All thicknesses | +15.0%, -12.5% |
| Out-of-roundness | Excluding weld seam | 0.015 D |
| Straightness | Full length | ≤ 0.2% L |
API 5L X65 Pipe Pressure Temperature Rating
The rated pressure for API 5L pipes is generally calculated using Barlow's Formula: P=2St/D×F
P: Internal design pressure.
S: Specified Minimum Yield Strength (450 MPa for X65).
t: Nominal wall thickness.
D: Outside diameter.
F: Design factor (usually 0.72 per industry standards).
Temperature Derating Factors: Pipe strength decreases as temperature increases.
-29°C to 121°C: Factor 1.0 (No reduction)
149°C: Factor 0.967
204°C: Factor 0.900
API 5L X65 ERW Pipe Coating Provided
To prevent soil or environmental corrosion, ERW pipes are often provided with the following coatings:
3LPE (Three-Layer Polyethylene): The most common external corrosion coating (FBE primer + Adhesive + PE outer layer).
FBE (Fusion Bonded Epoxy): Single or dual layer epoxy powder with excellent adhesion.
3LPP (Three-Layer Polypropylene): Suitable for high-temperature operating environments.
Varnish / Black Paint: Used for short-term rust prevention during storage and transit.
Internal Epoxy Lining: Reduces friction and improves flow efficiency.
Tests for API 5L X65 PSL2 ERW Pipe
| Test Item | Description |
| Hydrostatic Test | 100% of pipes are tested to ensure no leakage. |
| Flattening Test | Unique to ERW, it tests the ductility of the weld and material. |
| Non-Destructive Testing (NDT) | Ultrasonic (UT) or Electromagnetic testing on the weld seam. |
| Charpy Impact Test (CVN) | Mandatory for PSL2 to check toughness of body and weld heat-affected zone. |
| Guided-bend Test | Ensures the integrity and fusion of the weld. |
| Macroscopic Examination | Checks the metallurgical structure and fusion of the weld seam. |
API 5L X65 PSL2 ERW Pipe Factory
API 5L X65 PSL2 Resistance welded pipe test equipments
API 5L X65 PSL2 ERW carbon steel pipe certificate
FAQ
What is the difference between ERW pipe and normal pipe?
ERW pipes are made by rolling and welding steel strips, resulting in a longitudinal weld seam. They offer lower costs, higher efficiency, and very uniform wall thickness, making them ideal for standard medium-to-low pressure transportation. In contrast, "normal" seamless pipes are made by piercing solid steel billets and have no weld seam at all; they provide a more uniform structure and can withstand extreme pressures and temperatures, making them better suited for high-safety, critical operating conditions.
What is the difference between API 5L X60 and X65?
The primary difference between API 5L X60 and API 5L X65 is their yield strength. X65 is approximately 8% stronger than X60, which allows engineers to design pipelines with higher pressures or thinner walls to save on material and shipping costs.
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