Spiral Welded Pipe
Spiral welded pipes (SSAW) are manufactured by forming hot-rolled steel coils into a spiral and welding both the inside and outside with submerged arc welding (SAW). This production method allows for exceptionally large diameters up to DN3620 while maintaining excellent dimensional accuracy and weld quality. Our SSAW pipes conform to API 5L and SY/T5037 standards and undergo 100% ultrasonic testing of the weld seam.
The spiral weld geometry distributes stress more evenly around the pipe circumference, providing inherent resistance to hoop stress in pressurized applications. These pipes are widely used for long-distance water transmission, sewage treatment, structural piling, and oil & gas trunk pipelines where large diameter and cost-effectiveness are primary requirements.
API 5L / SY/T5037
Gr.B / Q235B
DN219-DN3620
Applications
- Long-distance water transmission mains
- Oil and gas trunk pipelines
- Sewage and wastewater treatment
- Structural piling and foundation works
- Dredging and slurry transport
Quality Assurance
All Spiral Welded Pipe products undergo NDT testing with MTC per EN 10204 3.1. Third-party inspection by SGS, BV, TUV available.
Spiral Welded Pipe Technical Specifications
Spiral welded pipe (SSAW/SAW) is manufactured from hot-rolled steel coil, formed into a spiral and welded with submerged arc welding (SAW). It is used for large-diameter water, gas, and oil transmission lines where cost-effectiveness and diameter flexibility are key.
| Parameter | Specification |
|---|---|
| Standard | API 5L / SY/T 5037 / EN 10217 / AWWA C200 |
| Grade | API 5L Gr.B, X42-X70; Q235B, Q345B, SS400 |
| Size Range | OD 219mm (8 inch) to 3620mm (144 inch), WT 4mm-25.4mm |
| Welding | Double submerged arc welding (DSAW), inside and outside |
| Length | 6-12m standard, up to 18m available |
| Coating | 3PE, FBE, coal tar enamel, cement mortar lining |
Manufacturing Process & Quality Control
Spiral pipe is produced by a continuous spiral forming and welding process:
- Coil Unrolling: Hot-rolled steel coil unrolled and leveled.
- Spiral Forming: Coil fed into a spiral forming machine at an angle, producing a continuous spiral pipe.
- Internal Welding: First SAW pass on inside of the spiral seam.
- External Welding: Second SAW pass on outside, completing the double-welded seam.
- Cutting: Cut to specified length.
- NDT: X-ray or ultrasonic testing of full seam length.
- Hydrotest: 100% hydrostatic test at 1.5x specified pressure per API 5L.
- End Preparation: Beveled ends for girth welding or flanged connections.
- Coating: External 3PE anti-corrosion coating, internal epoxy or cement lining per service requirements.
Advantages of spiral welded pipe include: ability to produce large diameters from narrower coil, lower cost than seamless for same diameter, and the spiral weld distributes stress along a longer weld line, reducing longitudinal stress concentration.
Applications
Spiral welded pipe is the standard for large-diameter transmission and distribution lines:
- Water Transmission: Municipal water supply mains, raw water intake lines, drainage culverts (DN800-DN3000).
- Oil and Gas: Onshore pipelines for crude oil and natural gas transmission.
- Piling: Steel pipe piles for foundations, docks, and bridge piers.
- Structural: Wind turbine towers, bridge components, building columns.
- Cement and Slurry: Mining slurry transport, cement plant piping.