An ERW (Electric Resistance Welded) pipe is formed by rolling a flat steel strip into a cylinder and welding the seam with an electric current — no filler material. ERW is the cost-efficient default for water, gas, structural and scaffolding work up to ~500 mm OD. In India it is governed mainly by BIS IS 1239 (Part 1) and, for larger sections, IS 3589.
How an ERW pipe is made
A coil of hot-rolled steel is slit to the right strip width, then formed through a series of forming rolls into a tube shape. As the strip edges meet, a high-frequency current passes across the seam — the electrical resistance heats the edges to forging temperature and pressure rolls fuse them together. Excess weld bead is scarfed off both inside and outside. The resulting pipe is sized, straightened, hydro-tested, and cut to length.
The process is continuous, fast, and dimensionally consistent — which is why ERW dominates the 15-500 mm OD range in India. It is not the right choice for high-pressure boiler service or sour-gas pipelines; for those, see seamless tubes.
When to specify ERW
- Structural sections (RHS / SHS) for fabrication, scaffolding, racking
- Cold and hot water lines under ~10 bar (BIS IS 1239 light/medium/heavy class)
- LPG / industrial gas distribution under low pressure with relevant grade
- Borewell casing and water-well tubes (commonly IS 4270)
- Surface conduit, fencing, automotive frames
When NOT to specify ERW
- High-pressure superheated steam in IBR boilers — use seamless boiler tubes per IS 6286 / ASTM A106
- Sour service or hydrogen-induced cracking risk applications — use seamless to API 5L sour-service grades
- Critical hydraulic cylinders requiring tight ID tolerance — use cold-drawn precision tubes
| Attribute | ERW | Seamless |
|---|---|---|
| Process | HR strip rolled + electric resistance weld | Hot-pierced billet, no weld |
| Typical OD range | 15 – 500 mm | 6 – 600 mm |
| Pressure rating | Up to ~10 bar (medium class) | Up to mill-rated, far higher |
| Cost (per kg) | Lower (~10-20% cheaper) | Higher |
| Lead time on stock sizes | 3-7 days | 7-21 days |
| IBR-suitable? | Generally no | Yes — IS 6286, ASTM A106 grades |
| Standards | IS 1239, IS 3589, IS 4923, ASTM A53 | IS 6286, ASTM A106, A179, A192 |
| Outer diameter (OD) | 15 mm to 500 mm (1/2" NB to 20" NB) |
|---|---|
| Wall thickness | 1.2 mm to 12 mm (light, medium, heavy class) |
| Indian standards | IS 1239 (Part 1), IS 3589, IS 4923, IS 4270 |
| International standards | ASTM A53, ASTM A500 (rectangular), API 5L |
| Grades | YST 210, YST 240, YST 310 (yield strength in MPa per IS 1161); ASTM A53 Gr A/B |
| Lengths | 6 m standard; up to 12 m on order |
| End finish | Plain end, beveled, threaded & coupled (T&C) |
| Documentation | Mill test certificate (MTC) standard; TPI on request |
- IS 1239 (Part 1):2004 — Steel Tubes for Water and Sewage — Specification — Bureau of Indian Standards (BIS)
- IS 3589:2001 — Steel Pipes for Water and Sewage (168.3 mm to 2540 mm OD) — Specification (Bureau of Indian Standards (BIS))
- ASTM A53/A53M-22 — Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless (ASTM International)
- API 5L 46th Ed. — Specification for Line Pipe (American Petroleum Institute)
- ERW Pipes & Tubes — product detail
- MS ERW Pipe Supplier in Kanpur
- How steel pipe pricing works
- Quality, MTC & TPI
- Steel Pipe Weight Calculator
- Glossary: ERW (Electric Resistance Welded)
- Glossary: IS 1239 Standard
- IS 1239 Steel Pipe Supplier
- ERW Pipe Sizes & Weight Chart
- Schedule 40 vs Schedule 80 ERW Pipe
- ERW Pipe for Boiler Applications
- ERW Pipe for Water Transmission
- ERW vs Seamless Pipe
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