API 5L GR.X56 Spiral Steel Pipe
In the demanding world of oil, gas, and water transmission, choosing the right pipe grade is critical for balancing safety, cost, and efficiency. API 5L Grade X56 Spiral Steel Pipe (also known as L390 line pipe) has emerged as a top-tier choice for engineering projects globally. Combining the high yield strength of X56 with the cost-effective SSAW (Spiral Submerged Arc Welded) process, this pipe is designed to handle high-pressure environments across vast distances.
Are you looking for a reliable supplier for your next pipeline project? Contact us today for a fast quote on API 5L X56 PSL2 SSAW pipes and technical support tailored to your specific requirements!
Technical Specifications of X56 SSAW Pipe
To ensure reliability in harsh conditions, API 5L X56 pipes are available in two product levels: PSL1 and PSL2.
Yield Strength: Min 390 MPa (56,600 psi).
Tensile Strength: Min 490 MPa (71,100 psi).
Manufacturing Process: SSAW (Spiral Submerged Arc Welded).
Outside Diameter (OD): 219.1mm – 3048mm.
Standard Wall Thickness: 5.0mm – 30mm.
API 5L X56 PSL2 SSAW Pipe Chemical and Mechanical Properties
Note: Values for PSL2 are more stringent than PSL1, specifically including Carbon Equivalent (CE) limits and Yield-to-Tensile ratios.
Chemical Composition (Max % for Welded PSL2)
| Grade | C | Mn | P | S | CEiiw (Max) | CEpcm (Max) |
| X56 PSL2 | 0.22 | 1.40 | 0.025 | 0.015 | 0.43 | 0.25 |
Mechanical Properties
| Grade | Yield Strength
Rt0.5Rt0.5 (MPa) |
Tensile Strength
RmRm (MPa) |
Yield-to-Tensile Ratio (Max) | Elongation (%) |
| X56 PSL2 | 390 - 540 | 490 - 760 | 0.93 | By formula* |
Dimensions And Sizes Of API 5L X56 Line Pipe (SSAW)
| Nominal Pipe Size (NPS) | Outside Diameter (mm) | Wall Thickness Range (mm) | Typical Length (m) |
| 8" | 219.1 | 5.0 – 14.27 | 6 / 12 / 18 |
| 12" | 323.8 | 6.0 – 17.48 | 6 / 12 / 18 |
| 18" | 457 | 6.35 – 23.83 | 12 / 18 / 22 |
| 24" | 610 | 7.1 – 25.4 | 12 / 18 / 22 |
| 32" | 813 | 8.0 – 25.4 | 12 / 18 / 22 |
| 40" | 1016 | 9.53 – 30.0 | 12 / 18 |
| 60" | 1524 | 10.0 – 30.0 | 12 |
| 80" | 2032 | 12.0 – 30.0 | 12 |
| 100" | 2540 | 14.0 – 30.0 | 12 |
| 120" | 3048 | 16.0 – 30.0 | 12 |
API 5L X56 Pipe Pressure Rating (Theoretical)
Calculated using Barlow's Formula: P=(2×S×T×F)/D
(S = Yield Strength, T = Wall Thickness, D = Outside Diameter, F = Design Factor 0.72)
| OD (inch) | Wall Thickness (mm) | Approx. Working Pressure (PSI) | Approx. Working Pressure (Bar) |
| 12.75" | 9.53 (SCH STD) | 2,330 | 160 |
| 24" | 12.70 | 1,680 | 115 |
| 36" | 15.88 | 1,400 | 96 |
| 48" | 17.48 | 1,150 | 79 |
API 5L X56 PSL2 Pipe Schedule Chart (Common Sizes)
While SSAW pipes are often custom-made, they generally follow ASME B36.10 wall thicknesses.
| OD (inch) | SCH 20 (mm) | SCH 30 (mm) | SCH 40 (mm) | SCH STD (mm) | SCH XS (mm) |
| 10.75" | 6.35 | 7.80 | 9.27 | 9.27 | 12.70 |
| 16" | 7.92 | 9.53 | 12.70 | 9.53 | 12.70 |
| 24" | 9.53 | 12.70 | 17.48 | 9.53 | 12.70 |
| 36" | 12.70 | 15.88 | 19.05 | 9.53 | 12.70 |
| 48" | 12.70 | 15.88 | 22.23 | 9.53 | 12.70 |
API 5L X56 PSL2 Welded Pipe Tolerance
| Parameter | Location | Tolerance |
| Outside Diameter (OD) | Pipe Ends | ±0.5% OD (Max ±4.0 mm / 0.160 in) |
| Pipe Body | ±0.75% OD | |
| Wall Thickness (WT) | t < 15.0 mm | +15.0%, -12.5% |
| t ≥ 15.0 mm | +15.0%, -10.0% | |
| Weight | Single Pipe | +10.0% / -3.5% |
| Straightness | Full Length | ≤ 0.2% of Total Length |
| Out-of-roundness | Pipe Ends | 1% of OD |
Key Advantages of Spiral Welded X56 Pipe
Cost-Efficiency for Large Diameters: The spiral welding process is significantly more economical for producing large-diameter pipes (above 24 inches) compared to seamless or longitudinal welded (LSAW) pipes.
Superior Dimensional Accuracy: Modern SSAW technology ensures high precision in diameter and wall thickness, facilitating easier on-site welding and alignment.
Flexible Customization: Spiral pipes can be produced in extended lengths (up to 22 meters or more), reducing the number of field joints and speeding up installation.
Optimized Strength: X56 provides a superior strength-to-weight ratio, making it ideal for high-pressure gas mains and deep-buried water trunk lines.
Global Applications of API 5L X56 SSAW Pipe
Due to its versatility, Grade X56 spiral pipe is widely used in several key sectors:
Oil & Gas Transmission: Onshore gathering and transmission lines for crude oil and natural gas.
Water Conservancy: Large-scale water diversion projects and urban water supply networks.
Dredging and Slurry: Transporting abrasive materials in mining and coastal reclamation.
Structural Piling: High-strength foundation piling for bridges, docks, and offshore platforms.
Quality Assurance and Protection
For international projects, quality is non-negotiable. Premium API 5L X56 SSAW pipes undergo 100% Hydrostatic testing, X-Ray inspection, and Ultrasonic testing. To prevent environmental degradation, these pipes are often paired with:
3PE Coating: (Three-layer Polyethylene) for maximum external corrosion protection.
FBE Coating: (Fusion Bonded Epoxy) for superior adhesion.
Internal Epoxy Lining: To reduce friction and enhance flow efficiency.
API 5L GR.X56 Spiral Steel Pipe Test Requirements
To comply with API 5L PSL2, the following tests are mandatory during the SSAW process:
Hydrostatic Test: 100% of pipes must be tested for leak resistance.
CVN Impact Test: Charpy V-Notch test at 0°C (or as specified) to ensure cold-weather toughness.
Ultrasonic Testing (UT): Full-length scan of the spiral weld seam and pipe ends.
X-Ray Inspection (RT): Radiographic testing of weld ends and critical sections.
Tensile Test: Verification of yield, tensile strength, and elongation.
Guided Bend Test: Ensures the weld seam does not crack when bent.
Visual & Dimensional: Inspection for surface defects, straightness, and ovality.
FAQ
What is the yield strength of X56 pipe?
The minimum yield strength of API 5L X56 pipe is:
56,600 psi
390 MPa (or 390 N/mm²)
What is a 5L pipe?
A 5L pipe refers to a steel pipe manufactured according to the API 5L specification, which is the international standard set by the American Petroleum Institute.
Purpose: It is used as line pipe to transport oil, natural gas, and water over long distances.
Types: It covers both Seamless and Welded (ERW, SSAW, LSAW) pipes.
Grades: It ranges from low strength (Grade B) to high strength (X42, X52, X56, X65, X70, X80).
Levels: It is divided into PSL1 (standard quality) and PSL2 (stricter quality for high-pressure or harsh environments).
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