30 9 月, 2026
ERW vs LSAW vs SSAW Pipe: Manufacturing Processes Compared
The three processes suit different sizes and duties. ERW covers the common small and medium diameters economically, LSAW handles large-diameter line pipe with a single longitudinal seam, and SSAW makes the largest diameters from a spiral seam. All three are welded pipe; the difference is how the seam is formed, how much it can be tested, and what that means for pressure service.
Side by side
| ERW | LSAW | SSAW | |
|---|---|---|---|
| Full name | Electric resistance welded | Longitudinal submerged arc welded | Spiral submerged arc welded |
| How the seam forms | Strip is rolled and the edges are welded by resistance heat | Plate is formed into a cylinder and welded along one longitudinal seam | Strip is wound spirally and welded along the spiral seam |
| Typical size range | Small to medium diameters, commonly up to around 24 in | Large diameters, from roughly 16 in upward | Very large diameters |
| Seam length per metre | Short — one longitudinal seam | Short — one longitudinal seam | Long — the spiral seam is longer per metre of pipe |
| Seam inspection | Eddy-current or ultrasonic on the weld | Ultrasonic and radiographic on the longitudinal seam | Ultrasonic and radiographic on the spiral seam |
| Typical use | Water, HVAC, structural tube, general service | Oil and gas transmission, large line pipe | Large-diameter water mains, piling, low-pressure transmission |
| Relative cost | Lowest for its size range | Higher — plate and heavier forming | Between ERW and LSAW for very large diameters |
Why the process matters to a buyer
Pressure design codes rate welded pipe with a longitudinal weld joint factor below 1.00, so the process and the extent of seam testing change the allowable pressure for the same size, wall and grade. When you specify a pipe, specify the process and the test level, not just the size and grade.
What to write in your enquiry
- The process or the standard that implies it, e.g. API 5L for line pipe
- Outside diameter, wall thickness and length
- The seam test level you require
- The end preparation and the surface finish
Related reading
Frequently asked questions
What does ERW pipe mean?
ERW stands for electric resistance welded. Strip is rolled into a cylinder and the longitudinal seam is welded by resistance heat. It is the most economical process for small and medium diameters.
Is LSAW better than ERW?
Neither is better in the abstract. LSAW suits large diameters and high-pressure line pipe; ERW suits small and medium diameters at lower cost. Choose by size, pressure and the standard named in the specification.
What is SSAW pipe used for?
Spiral submerged arc welded pipe is used for very large diameters, typically water mains, piling and lower-pressure transmission where large size matters more than seam efficiency.
Tell us the standard, grade, form and size you need and we will quote against it. See our steel product catalogue, how we inspect and certify each order, or request a quotation.