ERW Welded Steel Pipe (Round), DN15 to DN600
Straight-seam ERW welded steel pipe from DN15 to DN600 in Q195 and Q235B to GB/T 3091, for water mains, drainage, fire services, structural work and low-pressure process lines. Supplied in 6 m and 12 m lengths, plain end or bevelled, hydrostatically tested with mill certificate.
Product Overview
ERW welded pipe is made from steel strip that is cold formed into a round shape and welded along a single straight seam by resistance welding, without filler metal. The process is fast, the wall thickness is uniform, and the seam is a forged joint rather than a cast one, which is why straight-seam ERW pipe is the standard product for water, drainage, fire and general service up to about DN400.
The comparison with seamless pipe comes up in every enquiry. Seamless pipe has no seam, so it is preferred for high pressure, elevated temperature and fatigue duty. ERW pipe has a seam, but that seam is inspected, hydrostatically tested, and is not a weakness in ordinary pressure and structural service, while the pipe costs appreciably less per metre and is available in a wider range of thin walls and large diameters.
We supply ERW pipe designated by nominal bore from DN15 up to DN600, in Q195 and Q235B to GB/T 3091, with wall thicknesses from 1.5 mm to about 12 mm depending on size. Plain end, bevelled end and threaded-and-coupled finishes are available, and larger sizes above DN400 are produced to order.
Specifications & Size Range
Nominal bore, outside diameter, common wall thickness and the service each group is normally ordered for. Sizes above DN400 are made to order. End finish, length and any coating or lining requirement should be stated on the enquiry.
| Nominal bore | Outside diameter (mm) | Wall thickness (mm) | Standard length | Typical use |
|---|---|---|---|---|
| DN15 – DN50 | 21.3 / 26.9 / 33.7 / 42.4 / 48.3 / 60.3 | 1.5 – 4.0 | 6 m | Building services, small water and air lines, conduits, frames |
| DN65 – DN150 | 76.1 / 88.9 / 102 / 114.3 / 127 / 140 / 152 / 159 | 2.0 – 5.75 | 6 m / 12 m | Drainage, fire mains, sprinkler lines, plant pipework, piling |
| DN200 – DN300 | 203 / 219 / 245 / 273 / 299 / 325 | 4.0 – 9.75 | 6 m / 12 m | Stormwater and sewage mains, water trunk mains, gantry tubes |
| DN350 – DN400 | 377 / 426 | 5.0 – 9.75 | 6 m / 12 m | Large water mains, outfalls, structural tubular members |
| DN450 – DN600 | 457 / 508 / 610 | 6.0 – 12 | 6 m / 12 m, made to order | Large mains, plant cooling lines, pile casings, outfall pipes |
Tolerances
Dimensions, wall thickness and technical delivery follow GB/T 3091 for welded steel pipe for liquid service. Outside diameter, ovality, wall thickness and length tolerances are as set out in the standard and stated on the mill certificate. Every pipe can be hydrostatically tested, and weld integrity is checked by flattening or bend test through the production run.
Steel Grades & International Equivalents
All grades below are supplied with a mill test certificate. The right-hand column shows the material type and the Chinese standard the grade is produced to; the middle columns give the nearest recognised equivalent in other national standards. Exact equivalence for a specific project should be confirmed on the enquiry.
| GB (China) | ASTM / AISI (US) | EN (Europe) | JIS (Japan) | DIN (Germany) | Type / Standard |
|---|---|---|---|---|---|
| Q195 welded pipe | A53 Gr.A / A500 | EN 10255 (S195T) | SGP (JIS G3452) | St33 | Welded steel pipe (ERW) (GB/T 3091) |
| Q235B welded pipe | A53 Gr.B / A500 Gr.B | EN 10219 S235JRH | STK400 (JIS G3444) | St37-2 | Welded steel pipe (ERW / LSAW) (GB/T 3091) |
Grade Notes
- Q195 welded pipe — General-purpose welded pipe for water, gas, heating and structural framing.
- Q235B welded pipe — Structural welded pipe for scaffolding, piling, water mains and building frames.
Chemical Composition (%, ladle analysis)
Typical specification limits. Actual heat values are reported on the mill test certificate supplied with every shipment.
| Grade | C | Si | Mn | P max | S max | Other elements |
|---|---|---|---|---|---|---|
| Q195 welded pipe | ≤0.12 | ≤0.30 | 0.25–0.50 | ≤0.035 | ≤0.040 | — |
| Q235B welded pipe | ≤0.20 | ≤0.35 | ≤1.40 | ≤0.045 | ≤0.045 | — |
Mechanical Properties
Minimum values at room temperature unless stated. ReL = yield strength; Rp0.2 = 0.2% proof stress; Rm = tensile strength; A = elongation after fracture.
| Grade | Yield (ReL) | Proof (Rp0.2) | Tensile (Rm) | Elongation A | Impact / others | |
|---|---|---|---|---|---|---|
| Q195 welded pipe | ≥195 MPa | — | 315–430 MPa | ≥33% | — | Test Pressure hydro-tested per spec |
| Q235B welded pipe | ≥235 MPa | — | 370–500 MPa | ≥26% | — | Test Pressure hydro-tested per spec |
Standards & Documents
- GB/T 3091 — welded steel pipes for liquid service, dimensions and technical delivery
- GB/T 700 — carbon structural steels, covering Q195 and Q235B base strip
- ASTM A53 Gr.A / Gr.B and ASTM A500 — equivalent pipe specifications, on request
- EN 10255 (S195T) and EN 10219 S235JRH — European equivalents for pipe and structural tube
- JIS G3452 SGP and JIS G3444 STK400 — Japanese equivalents where called for
- Testing: hydrostatic pressure test to standard, weld flattening or bend test, EN 10204 3.1 mill test certificate
Typical Applications
| Industry / Application | Typical use |
|---|---|
| Municipal drainage & stormwater | Sewer and stormwater mains, culverts, road drainage and outfall lines, where a large diameter and a long length reduce jointing time. |
| Water supply & distribution | Raw and treated water mains, distribution lines and pumping station pipework, plain or cement-lined where the water is aggressive. |
| Fire protection systems | Fire mains, hydrant lines, sprinkler mains and standpipe risers, tested to the pressure class required by the design. |
| Structural tubular members | Scaffolding, columns, bracing, gantry and canopy members, and pipe trusses where the round section is efficient in compression. |
| Piling & ground works | Steel pipe piles, casing for bored piles, micro-pile sleeves and well casings, supplied cut to the driving length. |
| Industrial pipework & compressed air | Low-pressure process lines, cooling water, compressed air and ventilation and exhaust ducting. |
| Agricultural & irrigation lines | Irrigation mains, field distribution lines and livestock water systems in galvanized or plain finish. |
Common Problems Buyers Face — and How We Prevent Them
These are the issues that most often cause claims on steel imports. Each one is controlled in our process before shipment.
Weld seam defect found at receiving inspection
Why it happens: Strip edge condition, welding current drift or a worn forming roll will produce a seam defect, and the pipe is only rejected after it has travelled thousands of miles.
Our control: Welding parameters are set for the strip coil and recorded per lot, and seam quality is monitored by flattening and bend tests through the run. Where your specification requires ultrasonic inspection of the seam, that is quoted and performed before loading rather than argued about on arrival.
Pipe out of round so field joints will not align
Why it happens: Thin-wall and large-diameter pipe is flexible, so ovality develops through handling and stacking if the pipe is not supported properly.
Our control: Pipe ends are measured for roundness before loading and reported against the standard tolerance, and stacking is planned so the lower layers are not crushed. For field-welded lines we can supply the ends re-rounded and, where the diameter is critical, hold the ends with a ring.
Internal corrosion in a water line
Why it happens: Plain carbon steel in a wet, aerated service will corrode steadily, and internal corrosion in a buried main is expensive to put right.
Our control: Internal cement-mortar or epoxy lining can be applied before shipment and matched to the water chemistry. Alternatively specify hot-dip galvanized pipe for smaller sizes. Send the water analysis and we will quote the lining or coating that suits the service.
Field welding produces a joint that fails a pressure test
Why it happens: Pipe supplied square cut when the procedure needed a bevelled end, or with the wrong end preparation, leads to incomplete fusion at the root.
Our control: End preparation, whether plain, bevelled or threaded, is confirmed in writing on the order acknowledgement and shown on the packing list, so the pipe arrives in the condition your welding procedure assumes. Where a specific bevel angle is required, state it on the enquiry.
Pipe length tolerance does not match the installation method
Why it happens: Nominal 6 m or 12 m lengths carry a length tolerance that is acceptable for general work but not for a directional drilling or jacking procedure that needs exact lengths.
Our control: Tell us the installation method at the enquiry. For trenchless work and casing we cut to the required length within a tight tolerance and confirm the length tolerance band on the acknowledgement, rather than leaving it to the mill standard.
Our Supply & Manufacturing Advantages
- Wide size range from one source — DN15 to DN600 in one shipment, so small branch lines and large mains come with the same certificates and the same packing standard.
- Cost-effective versus seamless — For ordinary pressure and structural duty, ERW pipe costs appreciably less per metre and is available in thinner walls and larger diameters.
- Hydrostatically tested — Every pipe can be pressure tested to the standard or to your project figure, with the test pressure and duration recorded on the report.
- Seam quality controlled — Weld parameters are recorded per coil and the seam is verified by flattening or bend test, with ultrasonic inspection available on request.
- End finish to suit the procedure — Plain end, bevelled end, or threaded and coupled, so the pipe arrives ready for the jointing method the site will actually use.
- Lining and coating options — Cement-mortar or epoxy lining inside, and paint, bitumen or hot-dip galvanizing outside, chosen against the service conditions.
Packaging, Delivery & Payment
- Packing: loose in bulk vessel, or bundled and containerised to your requirement. Galvanized and coated products get VCI paper, waterproof wrapping and edge protection. See our export packaging methods.
- Availability: both stock and custom production. Tell us the specification and we will confirm the route.
- MOQ: no strict minimum — one ton can ship.
- Lead time: stock dispatched to port within 3 days; orders needing export packaging about 1 week; custom production quoted per product.
- Payment: stock — 10% deposit, balance before shipment; custom production — 50% deposit, balance before shipment.
- Documents: EN 10204 3.1 mill test certificate with every shipment; third-party inspection (SGS / BV) on request.
Frequently Asked Questions
What is the difference between ERW welded pipe and seamless pipe?
ERW pipe is formed from strip and has one longitudinal weld seam; seamless pipe is pierced from a solid billet and has no seam. Seamless pipe is preferred for high pressure, elevated temperature and fatigue duty, while ERW pipe is cheaper, available in thinner walls and larger diameters, and entirely adequate for water, drainage, fire and general structural service. For most municipal and building services, ERW is the correct and more economical choice.
Which grade should I use, Q195 or Q235B?
Q195 has the lower carbon content and better formability, and is the standard grade for thinner-wall pipe up to about DN150 in water, air and general service. Q235B has a higher specified yield strength of 235 MPa and is used where the pipe carries structural load, where the wall is thicker, or where the line is pressure-rated. Send the design pressure or the structural duty and we will nominate the grade and wall.
What hydrostatic test pressure is applied?
Pipe is tested to the pressure required by GB/T 3091 for its size and wall thickness, and each test report states the pressure applied and the duration. If the project specifies a different test pressure, state it at the enquiry and the pipe will be tested and reported against that figure so the certificate matches the specification being enforced.
What is the Chinese equivalent of ASTM A53 pipe?
Q235B pipe to GB/T 3091 is the closest Chinese equivalent to ASTM A53 Gr.B for general service, and Q195 pipe corresponds broadly to A53 Gr.A. The two are close on chemical composition and mechanical properties. If your project requires an A53 certificate rather than Chinese standard documentation, tell us and we will confirm what can be certified.
Can the pipe be supplied with cement lining?
Yes. Internal cement-mortar lining to the applicable standard and internal epoxy lining can both be applied before shipment. The right choice depends on the water chemistry, pH and chloride level, so send the water analysis and we will quote the lining system that suits the service and the design life.
Who supplies ERW welded steel pipe from China for export?
We do. Dayang supplies ERW welded pipe to water utilities, drainage contractors, fire-protection distributors and steel stockists worldwide from DN15 to DN600, plain, bevelled or threaded and coupled, with hydrostatic test records and mill certificates issued with every shipment.
Do you have a minimum order quantity?
No strict minimum and one ton can ship, but pipe is bulky and the freight economics favour container or vessel quantities, especially above DN200. We will tell you honestly where the break points are so that a small trial order is not quoted at an unrepresentative delivered cost.
What documents are supplied with a welded pipe shipment?
An EN 10204 3.1 mill test certificate showing heat number, chemical composition and mechanical properties, a hydrostatic test report, and where applicable weld inspection and coating or lining records. Commercial invoice, packing list and certificate of origin complete the set, and third-party inspection can be arranged before loading.
How is welded pipe packed and shipped?
Pipe up to about DN200 is bundled in hexagonal or square bundles for container loading. Larger diameters are containerised where possible or shipped break-bulk and in flat racks, nested and lashed, with end protection and, where needed, ring stiffeners at the ends so the pipe does not deform in the voyage.
Request a Quotation Export Packaging
Live Stock & Indicative Price
The table below lists live stock at the time of publication, with indicative EXW China reference prices in USD per tonne (converted at 6.70 CNY/USD). Steel prices move with the mill market every week — send us your size, quantity and destination and we will confirm availability and issue a firm FOB or CIF quotation.
| Product | Size / Model | Grade | Price (USD/t, EXW) | Stock (t) |
|---|---|---|---|---|
| ERW Welded Steel Pipe | DN15 × 1.8 mm | Q195 | $540 | 780 |
| ERW Welded Steel Pipe | DN15 × 2 mm | Q195 | $528 | 391 |
| ERW Welded Steel Pipe | DN15 × 2.2 mm | Q195 | $521 | 434 |
| ERW Welded Steel Pipe | DN15 × 2.5 mm | Q195 | $510 | 641 |
| ERW Welded Steel Pipe | DN15 × 2.75 mm | Q195 | $513 | 1364 |
| ERW Welded Steel Pipe | DN20 × 1.8 mm | Q195 | $537 | 518 |
| ERW Welded Steel Pipe | DN20 × 2 mm | Q195 | $525 | 1511 |
| ERW Welded Steel Pipe | DN20 × 2.2 mm | Q195 | $519 | 255 |
| ERW Welded Steel Pipe | DN20 × 2.5 mm | Q195 | $509 | 68 |
| ERW Welded Steel Pipe | DN20 × 2.75 mm | Q195 | $512 | 2756 |
| ERW Welded Steel Pipe | DN25 × 1.8 mm | Q195 | $531 | 46 |
| ERW Welded Steel Pipe | DN25 × 2 mm | Q195 | $521 | 1645 |
| ERW Welded Steel Pipe | DN25 × 2.2 mm | Q195 | $516 | 125 |
| ERW Welded Steel Pipe | DN25 × 2.5 mm | Q195 | $510 | 2332 |
| ERW Welded Steel Pipe | DN25 × 2.75 mm | Q195 | $507 | 1158 |
| ERW Welded Steel Pipe | DN25 × 3 mm | Q195 | $506 | 3330 |
| ERW Welded Steel Pipe | DN25 × 3.25 mm | Q195 | $507 | 2237 |
| ERW Welded Steel Pipe | DN32 × 1.8 mm | Q195 | $534 | 60 |
| ERW Welded Steel Pipe | DN32 × 2 mm | Q195 | $522 | 248 |
| ERW Welded Steel Pipe | DN32 × 2.2 mm | Q195 | $518 | 11 |
| ERW Welded Steel Pipe | DN32 × 2.5 mm | Q195 | $510 | 443 |
| ERW Welded Steel Pipe | DN32 × 2.75 mm | Q195 | $507 | 728 |
| ERW Welded Steel Pipe | DN32 × 3 mm | Q195 | $506 | 919 |
| ERW Welded Steel Pipe | DN32 × 3.25 mm | Q195 | $506 | 1099 |
| ERW Welded Steel Pipe | DN32 × 3.5 mm | Q195 | $512 | 187 |
| ERW Welded Steel Pipe | DN40 × 2.5 mm | Q195 | $512 | 1467 |
| ERW Welded Steel Pipe | DN40 × 2.75 mm | Q195 | $509 | 1282 |
| ERW Welded Steel Pipe | DN40 × 3 mm | Q195 | $506 | 1710 |
| ERW Welded Steel Pipe | DN40 × 3.25 mm | Q195 | $504 | 898868 |
| ERW Welded Steel Pipe | DN40 × 3.75 mm | Q195 | $512 | 774 |
| ERW Welded Steel Pipe | DN50 × 2 mm | Q235 | $527 | 312 |
| ERW Welded Steel Pipe | DN50 × 2.5 mm | Q235 | $512 | 597 |
| ERW Welded Steel Pipe | DN50 × 2.75 mm | Q235 | $509 | 360 |
| ERW Welded Steel Pipe | DN50 × 3 mm | Q235 | $506 | 939 |
| ERW Welded Steel Pipe | DN50 × 3.25 mm | Q235 | $504 | 731 |
| ERW Welded Steel Pipe | DN50 × 3.5 mm | Q235 | $507 | 806 |
| ERW Welded Steel Pipe | DN50 × 3.75 mm | Q235 | $510 | 463 |
| ERW Welded Steel Pipe | DN50 × 4.75 mm | Q235 | $533 | 332 |
| ERW Welded Steel Pipe | DN65 × 2.5 mm | Q235 | $510 | 405 |
| ERW Welded Steel Pipe | DN65 × 2.75 mm | Q235 | $507 | 329 |
| ERW Welded Steel Pipe | DN65 × 3 mm | Q235 | $506 | 476 |
| ERW Welded Steel Pipe | DN65 × 3.25 mm | Q235 | $504 | 174 |
| ERW Welded Steel Pipe | DN65 × 3.5 mm | Q235 | $503 | 623 |
| ERW Welded Steel Pipe | DN65 × 3.75 mm | Q235 | $503 | 380 |
| ERW Welded Steel Pipe | DN65 × 4 mm | Q235 | $506 | 234 |
| ERW Welded Steel Pipe | DN65 × 4.5 mm | Q235 | $510 | 170 |
| ERW Welded Steel Pipe | DN65 × 4.75 mm | Q235 | $519 | 138 |
| ERW Welded Steel Pipe | DN80 × 2.5 mm | Q235 | $510 | 253 |
| ERW Welded Steel Pipe | DN80 × 2.75 mm | Q235 | $507 | 112 |
| ERW Welded Steel Pipe | DN80 × 3 mm | Q235 | $506 | 124 |
| ERW Welded Steel Pipe | DN80 × 3.25 mm | Q235 | $504 | 240 |
| ERW Welded Steel Pipe | DN80 × 3.5 mm | Q235 | $503 | 543 |
| ERW Welded Steel Pipe | DN80 × 3.75 mm | Q235 | $503 | 506 |
| ERW Welded Steel Pipe | DN80 × 4 mm | Q235 | $503 | 393 |
| ERW Welded Steel Pipe | DN80 × 4.5 mm | Q235 | $510 | 181 |
| ERW Welded Steel Pipe | 89 × 5.75 mm | Q235 | $552 | 10 |
| ERW Welded Steel Pipe | DN100 × 2.5 mm | Q235 | $515 | 250 |
| ERW Welded Steel Pipe | DN100 × 2.75 mm | Q235 | $504 | 270 |
| ERW Welded Steel Pipe | DN100 × 3 mm | Q235 | $500 | 508 |
| ERW Welded Steel Pipe | DN100 × 3.25 mm | Q235 | $497 | 174 |
| ERW Welded Steel Pipe | DN100 × 3.5 mm | Q235 | $494 | 298 |
| ERW Welded Steel Pipe | DN100 × 3.75 mm | Q235 | $494 | 432 |
| ERW Welded Steel Pipe | DN100 × 4 mm | Q235 | $494 | 239 |
| ERW Welded Steel Pipe | DN100 × 4.5 mm | Q235 | $501 | 100 |
| ERW Welded Steel Pipe | DN100 × 4.75 mm | Q235 | $509 | 234 |
| ERW Welded Steel Pipe | 102 × 2.75 mm | Q235 | $513 | 113 |
| ERW Welded Steel Pipe | 102 × 3 mm | Q235 | $510 | 154 |
| ERW Welded Steel Pipe | 102 × 3.5 mm | Q235 | $507 | 143 |
| ERW Welded Steel Pipe | 102 × 3.75 mm | Q235 | $507 | 192 |
| ERW Welded Steel Pipe | 102 × 4 mm | Q235 | $507 | 157 |
| ERW Welded Steel Pipe | 102 × 4.5 mm | Q235 | $507 | 74 |
| ERW Welded Steel Pipe | 102 × 4.75 mm | Q235 | $507 | 66 |
| ERW Welded Steel Pipe | 108 × 2.5 mm | Q235 | $516 | 182 |
| ERW Welded Steel Pipe | 108 × 2.75 mm | Q235 | $513 | 211 |
| ERW Welded Steel Pipe | 108 × 3 mm | Q235 | $510 | 273 |
| ERW Welded Steel Pipe | 108 × 3.5 mm | Q235 | $507 | 307 |
| ERW Welded Steel Pipe | 108 × 3.75 mm | Q235 | $507 | 350 |
| ERW Welded Steel Pipe | 108 × 4 mm | Q235 | $507 | 198 |
| ERW Welded Steel Pipe | 108 × 4.5 mm | Q235 | $507 | 129 |
| ERW Welded Steel Pipe | 108 × 4.75 mm | Q235 | $507 | 153 |
| ERW Welded Steel Pipe | 114 × 5.75 mm | Q235 | $534 | 67 |
| ERW Welded Steel Pipe | 121 × 2.75 mm | Q235 | $515 | 206 |
| ERW Welded Steel Pipe | 121 × 3 mm | Q235 | $512 | 328 |
| ERW Welded Steel Pipe | 121 × 3.5 mm | Q235 | $507 | 391 |
| ERW Welded Steel Pipe | 121 × 3.75 mm | Q235 | $507 | 453 |
| ERW Welded Steel Pipe | 121 × 4 mm | Q235 | $510 | 316 |
| ERW Welded Steel Pipe | 121 × 4.75 mm | Q235 | $507 | 213 |
| ERW Welded Steel Pipe | 121 × 5.75 mm | Q235 | $521 | 12 |
| ERW Welded Steel Pipe | DN125 × 3.5 mm | Q195 | $509 | 1394 |
| ERW Welded Steel Pipe | DN125 × 2.75 mm | Q235 | $534 | 22 |
| ERW Welded Steel Pipe | DN125 × 3 mm | Q235 | $513 | 294 |
| ERW Welded Steel Pipe | DN125 × 3.5 mm | Q235 | $506 | 202 |
| ERW Welded Steel Pipe | DN125 × 3.75 mm | Q235 | $506 | 289 |
| ERW Welded Steel Pipe | DN125 × 4 mm | Q235 | $506 | 344 |
| ERW Welded Steel Pipe | DN125 × 4.25 mm | Q235 | $506 | 76 |
| ERW Welded Steel Pipe | DN125 × 4.5 mm | Q235 | $506 | 307 |
| ERW Welded Steel Pipe | DN125 × 4.75 mm | Q235 | $513 | 301 |
| ERW Welded Steel Pipe | 127 × 2.75 mm | Q235 | $516 | 198 |
| ERW Welded Steel Pipe | 127 × 3 mm | Q235 | $513 | 302 |
| ERW Welded Steel Pipe | 127 × 3.5 mm | Q235 | $507 | 252 |
Showing 100 of 198 listed sizes (lowest prices first). Price range USD 494–552 per tonne (EXW China). MOQ from 1 tonne; stock dispatched to port within 3 days. Mill test certificate (EN 10204 3.1) and third-party inspection available on request.