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straight seam steel pipe

Straight seam steel pipes are manufactured by rolling steel plates or coils into a cylindrical shape with the seam running parallel to the pipe axis. They are produced via High-Frequency Electric Resistance Welding (ERW/LSAW) or Submerged Arc Welding (LSAW). Compared to spiral pipes, straight seam pipes offer higher dimensional accuracy, superior roundness, and excellent performance for medium-to-large diameters and high-pressure applications.

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Product Details

1. Product Overview

Straight Seam Steel Pipe (Longitudinal Welded Steel Pipe)

2. Specification & Dimensions

Note: Specific ranges depend on the manufacturing process (ERW vs. LSAW).

Outer Diameter (OD):

ERW: Φ21mm – Φ610mm (1/2" – 24")

LSAW: Φ406mm – Φ1620mm (16" – 64") and above

Wall Thickness (WT): 2.0mm – 60mm (Custom heavy-wall available)

Length:

Standard: 6m / 12m (Single Random / Double Random)

Fixed Length: 5.8m, 6m, 11.8m, 12m (for container shipping)

Custom cutting available

Tolerance:

OD: ±0.5% (ERW) / ±1% (LSAW)

WT: ±5% / ±10%

Length: +50mm

3. Material & Steel Grades

Carbon Steel: Q235A/B/C, Q345 (Q355), 16Mn, 20#

Pipeline Steel (API 5L): L245 (Gr.B), L290 (X42), L320 (X46), L360 (X52), L415 (X60), L450 (X65), L485 (X70)

High-Grade Line Pipe: X42, X46, X52, X56, X60, X65, X70, X80

ASTM/EN Standards:ASTM A53, A106, A252, A500EN S235JRH, S275JRH, S355J2H

4. Executive Standards

GB/T 3091: Welded steel pipes for low pressure liquid delivery

GB/T 9711: Petroleum and natural gas industries steel pipe

SY/T 5037 / SY/T 5040: Straight seam welded pipe for fluid conveyance/piling

API Spec 5L: Specification for line pipe (PSL1 / PSL2)

ASTM A53 / A106 / A252: Standard specifications for pipe, steel, black and hot-dipped, zinc-coated welded and seamless; Welded and seamless steel pipe piles

EN 10217 / EN 10219: Welded steel tubes for pressure/structural purposes

5. Mechanical & Performance Features

High Dimensional Accuracy: Excellent roundness and straightness, ideal for precise engineering.

Superior Weld Quality: Single longitudinal weld seam (LSAW) or high-frequency ERW seam ensures strong bonding and pressure resistance.

High Pressure Resistance: Suitable for high-yield strength applications and heavy-wall requirements.

Deformation Resistance: Good toughness and impact resistance in low/high temperatures (depending on grade).

Versatile Coating Compatibility: Easily adapted for 3PE, FBE, epoxy, and galvanized coatings.

6. End Preparation

Plain End (PE): Square cut for general construction.

Beveled End (BE): 30°/35° bevel with root face for welding (standard for pipelines).

Threaded & Coupled (T&C): Common for smaller ERW pipes.

Flanged Ends: Available on request.

End Protectors: Plastic or steel caps to prevent damage.

7. Surface Treatment & Anti-Corrosion

Bare / Black Varnish: Anti-rust oil for short-term storage.

Hot-Dip Galvanized: For corrosion resistance (common in ERW).

External Coating: 3PE/3PP, FBE (Fusion Bonded Epoxy), Coal Tar Epoxy, Polyurethane.

Internal Lining: Cement Mortar, Liquid Epoxy, IPN8710 (drinking water standard).

8. Testing & Inspection

Dimensional Check: OD, WT, Length, Ovality.

Weld Inspection: Ultrasonic Testing (UT) of the longitudinal seam, X-Ray (RT) for LSAW.

Hydrostatic Test: 100% hydrostatic pressure test for ERW; sampled for LSAW.

Mechanical Tests: Tensile, Flattening, Impact (Charpy V-notch), Hardness.

Chemical Analysis: Spectrometer testing for material grades.

MTC: Mill Test Certificate provided (EN 10204 3.1/3.2).

9. Typical Applications

Oil & Gas: Trunk pipelines, gathering lines (LSAW).

Water & Drainage: Urban water supply, sewage, raw water diversion.

Structural: Building columns, bridge piers, stadium structures.

Piling: Deep foundation steel pipe piles (marine/port).

Industrial: Chemical plants, power stations, heating networks.

10. Packing & Delivery

Packing: Bundle packing with steel strips, end caps, woven bags for small OD; loose/bulk for large OD.

Shipping: Containers (20ft/40ft) for standard lengths; Bulk vessel for oversized LSAW pipes.

Marking: Heat number, OD, WT, Length, Standard, Manufacturer.

"SUNRISE supplies high-quality Straight Seam Steel Pipes (ERW/LSAW) ranging from Φ21mm to Φ1620mm, with wall thickness up to 60mm. Compliant with API 5L, GB/T 9711, ASTM, and EN standards, our pipes deliver exceptional dimensional accuracy and pressure resistance for oil & gas, water, and structural projects. Custom coatings and mill certifications available."