ERW (Electric Resistance Welded) steel pipe is a cost-effective tubular solution for structural, mechanical, and low-pressure fluid applications. Unlike seamless pipe, ERW pipe is formed from flat-rolled steel strip (skelp) that is cold-formed into a cylindrical shape and welded longitudinally using electric resistance heating — no filler metal is added. Huaxia-Steel supplies ERW carbon steel pipe from 1/2" to 24" in diameter, with wall thicknesses from SCH10 to SCH160, to ASTM A53, ASTM A500, ASTM A252, and EN 10219 standards.
Product Overview: ERW Welded Steel Pipe
ERW pipe is the most widely used welded pipe type in construction, infrastructure, water transmission, and general mechanical applications. The electric resistance welding process creates a forge weld — the edges of the steel strip are heated to forging temperature by electrical resistance and pressed together under pressure, producing a solid-state bond without melting. The external weld flash is trimmed, and the pipe may be heat-treated (normalized) to refine the weld zone microstructure for critical applications.
| Property | Specification |
|---|---|
| Material | Carbon steel (S235JR, S355J2, ASTM A53 Gr.A/B, ASTM A500 Gr.B/C, Q235B) |
| Outside diameter | 1/2" to 24" (21.3mm to 610mm) |
| Wall thickness | SCH10, SCH20, SCH40, SCH80, SCH160 (2.11mm to 59.54mm) |
| Length | 6m, 12m standard (random length or fixed length) |
| Surface treatment | Black (mill finish), oiled, galvanized (HDG), painted, 3LPE coated |
| Certification | EN 10204 3.1 MTC, hydrostatic test, NDT available |
Specification Table: Size, Weight, and Wall Thickness
| NPS (inch) | OD (mm) | SCH40 WT (mm) | SCH40 Weight (kg/m) | SCH80 WT (mm) | SCH80 Weight (kg/m) | SCH160 WT (mm) |
|---|---|---|---|---|---|---|
| 1/2 | 21.3 | 2.77 | 1.27 | 3.73 | 1.62 | 4.78 |
| 3/4 | 26.7 | 2.87 | 1.69 | 3.91 | 2.20 | 5.56 |
| 1 | 33.4 | 3.38 | 2.50 | 4.55 | 3.24 | 6.35 |
| 1-1/2 | 48.3 | 3.68 | 4.05 | 5.08 | 5.41 | 7.14 |
| 2 | 60.3 | 3.91 | 5.44 | 5.54 | 7.48 | 8.74 |
| 2-1/2 | 73.0 | 5.16 | 8.63 | 7.01 | 11.41 | 9.53 |
| 3 | 88.9 | 5.49 | 11.29 | 7.62 | 15.27 | 11.13 |
| 4 | 114.3 | 6.02 | 16.07 | 8.56 | 22.32 | 13.49 |
| 6 | 168.3 | 7.11 | 28.26 | 10.97 | 42.56 | 18.26 |
| 8 | 219.1 | 8.18 | 42.55 | 12.70 | 64.64 | 23.01 |
| 10 | 273.1 | 9.27 | 60.31 | 15.09 | 96.01 | 28.58 |
| 12 | 323.9 | 10.31 | 79.73 | 17.48 | 132.05 | 33.32 |
| 16 | 406.4 | 12.70 | 123.30 | 21.44 | 203.54 | 40.49 |
| 20 | 508.0 | 15.09 | 183.43 | 26.19 | 311.17 | 50.01 |
| 24 | 610.0 | 17.48 | 255.43 | 30.96 | 442.08 | 59.54 |
Weights based on plain-end pipe (no threads or couplings). For galvanized pipe, add approximately 3-5% to weight.
Available Grades and Standards
| Standard | Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Application |
|---|---|---|---|---|
| ASTM A53 | Gr.A / Gr.B | 205 / 240 | 330 / 415 | Pressure piping, steam, water, gas |
| ASTM A500 | Gr.B / Gr.C | 315 / 345 | 400 / 425 | Structural tubing, columns, bracing |
| ASTM A252 | Gr.2 / Gr.3 | 240 / 310 | 415 / 455 | Pipe piling, deep foundations |
| ASTM A135 | Gr.A / Gr.B | 205 / 240 | 330 / 415 | Electric resistance welded pipe |
| EN 10219 | S235JRH / S355J2H | 235 / 355 | 360-510 / 470-630 | Cold-formed welded structural hollow sections |
| API 5L | Gr.B / X42 / X52 | 245 / 290 / 360 | 415 / 415 / 460 | Line pipe for oil and gas transmission |
| GB/T 3091 | Q235B / Q355B | 235 / 355 | 370-500 / 470-630 | Welded steel pipe for low pressure liquid delivery |
Manufacturing Process and Quality Control
ERW manufacturing steps:
- Sklep preparation: Hot-rolled steel coil is uncoiled, leveled, and edge-trimmed to width exactly matching the pipe circumference.
- Cold forming: The strip passes through a series of roll-forming stands that progressively curve the strip into a cylindrical shape.
- Electric resistance welding: A high-frequency induction coil or sliding contact electrodes heat the strip edges to forging temperature (1,300-1,400°C). Squeeze rolls immediately press the heated edges together, forming a solid-state forge weld.
- External flash removal: The external weld bead (flash) is trimmed by a cutting tool immediately after welding.
- Post-weld heat treatment (optional): The weld zone may be normalized (heated above Ac3 and air-cooled) to refine the weld microstructure and reduce HAZ hardness.
- Sizing and straightening: The pipe passes through sizing stands and a straightening machine to achieve final dimensions and straightness.
- Cutting: The continuous pipe is cut to length (6m or 12m) by a flying saw.
- End finishing: Ends are squared, beveled (for welding), or threaded per customer specification.
Quality control tests on every lot:
- Hydrostatic test (minimum 5 seconds hold at specified pressure per ASTM/API) — 100% of pipes
- Eddy current or ultrasonic inspection of weld seam — 100% for critical grades
- Flattening test (weld at 0° or 90°) per ASTM A53/A500
- Tensile test on base metal and transverse weld specimen
- Bend test (guided bend) on weld specimen
- Dimensional verification (OD, wall thickness, length, straightness, end squareness)
Surface Treatment Options
| Treatment | Specification | Coating Thickness | Application |
|---|---|---|---|
| Black (mill finish) | As-welded with light oil | N/A | Indoor, dry environments |
| Hot-dip galvanized | ASTM A53 / A123 | 45-85 µm | Outdoor, water exposure |
| Pre-galvanized | ASTM A653 | 20-30 µm | Light-duty outdoor |
| Varnished / Painted | Epoxy, alkyd, polyurethane | 50-200 µm | Corrosive environments |
| 3LPE coated | DIN 30670 / CSA Z245.21 | 1.8-3.7mm | Buried pipeline |
| FBE coated | AWWA C213 | 300-500 µm | Water pipeline |
Packaging and Shipping
| Package Type | Pipe Size | Quantity per Bundle | Weight |
|---|---|---|---|
| Hexagonal bundle (steel strapped) | 1/2" to 4" | 37-217 pcs | 1-3 MT |
| Square bundle (steel strapped) | 6" to 12" | 7-61 pcs | 2-5 MT |
| Loose (with end protectors) | 14" to 24" | Individual | 0.3-1.5 MT/pc |
All pipe ends are protected with plastic caps or bevel protectors. Threaded pipe ends are fitted with thread protectors. Each bundle carries a weatherproof tag with heat number, grade, size, and quantity. Pipes are shipped in 20' or 40' containers for diameters up to 16", or as breakbulk cargo for larger diameters.
Conclusion
ERW welded steel pipe offers an economical alternative to seamless pipe for structural, mechanical, and low-pressure applications. With diameters from 1/2" to 24", wall schedules from SCH10 to SCH160, and material grades covering ASTM A53, A500, A252, and EN 10219, ERW pipe meets the requirements of most construction, infrastructure, and industrial projects. The key to reliable ERW pipe procurement is sourcing from mills with certified welding procedures, comprehensive NDT capabilities, and consistent quality documentation.
Need ERW welded carbon steel pipe for your project? Contact Huaxia-Steel for mill-direct pricing, full MTC, hydrostatic test reports, and global containerized or breakbulk shipping.
