SSAW pipe is formed by helically welding a steel strip into a continuous spiral seam, while ERW pipe is formed from a strip bent into a round shape and welded along a straight longitudinal seam. The two methods have complementary strengths.
Where SSAW Excels
SSAW is ideal for large-diameter pipe, often from DN200 up to DN3800 or larger, using a relatively narrow strip. This makes it efficient for water mains, piling, and large energy or structural lines.
Because the weld runs along a helix, SSAW can support long continuous lengths and flexible production across many diameter and wall combinations.
Where ERW Excels
ERW is highly efficient for small and medium diameters, often up to around DN600 or DN700, with consistent wall thickness and a clean external appearance. It is common for distribution piping and mechanical tubing.
For very large diameters, ERW becomes less practical because it requires wider steel strip and larger forming equipment. This is where SSAW becomes the more economical route.
Side-by-Side Comparison
| Item | SSAW | ERW |
|---|---|---|
| Forming | Helical strip forming | Straight longitudinal seam |
| Ideal diameter | DN200 - DN3800+ | Small to medium diameters |
| Wall range | 5 - 25 mm typical | Thinner walls common |
| Seam geometry | Spiral seam | Single longitudinal seam |
Key Takeaways
- SSAW is the practical route for large-diameter pipe.
- ERW is efficient for small and medium diameters.
- Confirm the required standard and application before finalizing the welding method.
- For structural piling and water mains, SSAW often provides the best large-diameter value.