Spiral Welded Steel Pipe (SSAW), DN200–DN2600
Large-diameter spiral submerged-arc welded (SSAW) steel pipe from DN200 to DN2600 in Q235B and Q355B, wall thickness 5 to 25 mm, produced to SY/T 5037 or API 5L as required. Used for water mains, outfalls, oil and gas transmission, and pile foundations. Hydro test, weld radiography and mill certificate supplied.
Product Overview
Spiral welded pipe is made from a steel coil that is formed into a helix and welded inside and out by submerged arc welding. Because the coil is fed continuously, the finished diameter is limited by the mill rather than by the plate width, which is why spiral pipe is the only economic way to make very large diameter pipe — DN600 and above, up to DN2600. The helical weld is inherently stronger against internal pressure and thermal expansion than a straight seam of the same length, and the pipe is normally the cheapest large-diameter option available.
Typical specification: outer diameter DN200–DN2600 (219–2620 mm), wall thickness 5–25 mm, material Q235B or Q355B to GB/T 700 and GB/T 1591, dimensions and technical delivery to SY/T 5037 (the Chinese standard for spiral welded pipe for pipelines of water, gas and heat) or to API 5L when the enquiry demands it. Lengths are supplied 6–12 m as standard, and specific lengths can be produced to order for trenchless or road-crossing work.
Each pipe can be supplied with hydrostatic pressure test, weld radiography or ultrasonic testing, and the coating of your choice — bare, cement-lined, epoxy, or three-layer polyethylene — according to the service. End preparation is bevelled, plain or fitted with a pipe cap, so the pipe arrives ready for the site procedure you will actually use.
Specifications & Size Range
Standard outside diameters, wall thicknesses and materials. Sizes outside the range, special lengths and heavier wall thickness are made to order.
| Nominal diameter | Outside diameter (mm) | Wall thickness (mm) | Material | Typical service |
|---|---|---|---|---|
| DN200 – DN400 | 219 / 273 / 325 / 377 / 426 | 5 – 10 | Q235B, Q355B | Outfall pipes, plant water lines, piling sleeves |
| DN450 – DN800 | 478 / 529 / 630 / 720 / 820 | 6 – 12 | Q235B, Q355B | Water mains, stormwater, gas transmission |
| DN900 – DN1400 | 920 / 1020 / 1220 / 1420 | 8 – 16 | Q235B, Q355B | City water trunk mains, river crossings |
| DN1500 – DN2600 | 1520 / 1820 / 2020 / 2220 / 2620 | 10 – 25 | Q235B, Q355B | Large outfalls, desalination intakes, sea outfalls |
Tolerances
Dimensions and technical delivery to SY/T 5037-2018; API 5L on request. Diameter, ovality, wall thickness, length and straightness tolerances as per the referenced standard, stated on the mill certificate. Coating thickness tested to the applicable coating standard.
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 |
|---|---|---|---|---|---|
| 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) |
| Q355B | A572 Gr.50 / A992 | S355JR (EN 10025-2) | SM490 (JIS G3106) | St52-3 | High-strength low-alloy (HSLA) steel (GB/T 1591) |
Grade Notes
- Q235B welded pipe — Structural welded pipe for scaffolding, piling, water mains and building frames.
- Q355B — High-strength structural steel for heavy structures, bridges and towers. Equivalent to ASTM A572 Gr.50 / EN S355JR.
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 |
|---|---|---|---|---|---|---|
| Q235B welded pipe | ≤0.20 | ≤0.35 | ≤1.40 | ≤0.045 | ≤0.045 | — |
| Q355B | ≤0.24 | ≤0.55 | ≤1.60 | ≤0.035 | ≤0.035 | Ceq ≤0.45 |
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 | |
|---|---|---|---|---|---|---|
| Q235B welded pipe | ≥235 MPa | — | 370–500 MPa | ≥26% | — | Test Pressure hydro-tested per spec |
| Q355B | ≥355 MPa (≤16 mm) | — | 470–630 MPa | ≥22% | +20 °C, ≥27 J | — |
Standards & Documents
- SY/T 5037 — spiral submerged-arc welded steel pipe for pipelines of water, gas and heat
- API 5L — specification for line pipe (PSL1 / PSL2 on request)
- GB/T 9711 — petroleum and natural gas industries, steel pipe for pipeline transportation
- GB/T 700 (Q235B) and GB/T 1591 (Q355B) — base plate grades
- GB/T 3091 / GB/T 6728 — welded steel pipe for general and structural service
- Testing: hydrostatic pressure test to standard, weld radiography or ultrasonic testing, EN 10204 3.1 mill certificate
Typical Applications
| Industry / Application | Typical use |
|---|---|
| Municipal water & drainage mains | Water transmission trunk mains, stormwater and sewage outfalls, and river or sea outfalls, where the large diameter keeps flow velocity and pumping cost down. |
| Oil & gas transmission | Long-distance gathering and transmission lines, produced to API 5L or GB/T 9711 with the corresponding weld and pressure testing regime. |
| Pile foundations & marine works | Steel pipe piles, wharf piles, bridge foundations and coffer-dam elements, supplied with bevelled ends ready for driving or welding. |
| Structural tubular members | Long-span pipe trusses, stadium and canopy structures, and bridge arch ribs, where the helical seam distributes stress evenly. |
| Plant piping & power stations | Circulating water lines, cooling-water pipework, ash-handling lines and desalination intake and outfall pipework. |
| Irrigation & drainage schemes | Canal liners, irrigation mains and land-drainage lines in large-diameter schemes where cost per metre is decisive. |
| Trenchless & road crossings | Jacking pipe and casing for crossings, supplied to the exact length and end configuration the jacking method requires. |
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 porosity or incomplete penetration found by the receiving inspector
Why it happens: Coil surface condition, welding current drift or a flux that has absorbed moisture will all show up as weld defects, and the pipe is rejected only after it has travelled half way round the world.
Our control: Welding parameters are fixed for the coil and recorded per pipe, flux is stored dry, and a sample of the production run is radiographed before loading. Where your specification calls for full radiography or ultrasonic testing of every pipe, that is quoted and performed before shipment, not argued about on arrival.
Out-of-round pipe that will not align for welding on site
Why it happens: Large thin-wall spiral pipe is flexible, and ovality develops through handling, stacking and long transit if it is not supported properly.
Our control: Pipe ends are held with internal or external ring stiffeners, and stacking is planned so the bottom layers are not crushed. Ovality is measured at the pipe ends before loading and reported against the standard tolerance.
Internal corrosion appearing early in service
Why it happens: Bare carbon steel in a water or sewage service will corrode quickly, and internal corrosion in a large main is expensive to repair.
Our control: Internal cement-mortar lining or epoxy lining can be applied before shipment, matched to the water chemistry and to the pH and chloride level of the service. Tell us the water analysis and we will quote the lining system.
Coating damaged in transit, leaving bare steel
Why it happens: External three-layer PE or epoxy coating is easily scuffed by chains and spreaders where the pipe is handled without protection.
Our control: Coated pipe is handled with belt slings and nylon slings rather than chains, and end protection and spacers are fitted before loading. Repair material for site touch-up is supplied with the shipment.
Pipe length or end preparation not matching the site procedure
Why it happens: Pipe ordered to a nominal length without agreeing the end condition arrives with square cut ends when the contractor needed bevelled ends, or the reverse.
Our control: End preparation — plain end, bevelled end, or with cap — and the length tolerance are both confirmed in writing on the order acknowledgement, and the fabrication drawing is attached to the production traveller.
Our Supply & Manufacturing Advantages
- Large diameters others cannot roll — DN200 to DN2600 from coil, including diameters that are impractical in straight-seam or seamless production.
- Cost-effective per metre — For any diameter above about DN600 the spiral route is normally the lowest cost per metre of pipe delivered, with no sacrifice on pressure rating.
- Testing done before loading — Hydrostatic test, radiography or ultrasonic testing and dimensional checks are completed at the mill so a failure is found in China, not at your port.
- Coating and lining matched to service — Bare, cement-lined, epoxy-lined, or three-layer PE outside, chosen against the water or product chemistry you tell us.
- Stock sizes on fast dispatch — Common diameters and wall thicknesses are held in stock for dispatch to port within 3 days; special sizes are produced to order.
- Documented and traceable — EN 10204 3.1 mill certificate, hydrostatic test report, weld inspection report and coating thickness record with every shipment.
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 spiral welded pipe and straight seam (ERW / LSAW) pipe?
Spiral welded pipe is formed from coil into a helix and welded both inside and outside, so it can be made in much larger diameters — up to DN2600 — and the helical seam spreads stress more evenly along the pipe. Straight-seam pipe (ERW for small sizes, LSAW for large) is normally used up to about DN1000. For large-diameter water, outfall and pile work, spiral pipe is the standard and the most economical choice.
Which grade should I use for a water main, Q235B or Q355B?
For most municipal water and drainage mains Q235B is sufficient and is the most economical. Q355B is used where a higher design pressure, thinner wall for the same pressure rating, or greater resistance to ground movement is required. Send us the design pressure, diameter and burial depth and we will nominate the grade and wall thickness.
Do you supply to API 5L?
Yes. Spiral pipe can be produced to API 5L PSL1 or PSL2 with the corresponding chemical, mechanical and testing requirements, including hydrostatic testing and weld inspection. The standard required should be stated on the enquiry because it changes the testing regime and the certificate.
Can the pipe be cement-lined or epoxy-lined?
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 content, so send us the water analysis and we will quote the lining system that suits the service.
What testing is carried out on the pipe?
Every pipe can be hydrostatically pressure tested to the standard, and weld testing by radiography or ultrasonic inspection can be applied to a sample or to every pipe, as your specification requires. Dimensional checks, coating thickness measurement and the mill test certificate are provided as standard.
Do you have a minimum order quantity?
No strict minimum. Small orders of one ton can ship, though for large-diameter pipe the freight economics strongly favour container or vessel quantities, and we will tell you honestly where the break points are.
How is large diameter pipe shipped?
Pipe up to about DN600 is normally containerised. Larger diameters are shipped break-bulk or in flat racks, nested and lashed, with end protection and spacers. We plan the stow so that the pipe is supported along its length and does not deform during the voyage.
What is the lead time for spiral welded pipe?
Common stock diameters and wall thicknesses are dispatched to the port within 3 days. Pipes requiring coating, lining, special lengths or full weld testing typically take about one week to reach the port; custom production is quoted per item.
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) |
|---|---|---|---|---|
| Spiral Welded Pipe | Ø219 × 8 mm | Q235B | $522 | 49 |
| Spiral Welded Pipe | Ø273 × 5 mm | Q235B | $522 | 59 |
| Spiral Welded Pipe | Ø273 × 6 mm | Q235B | $522 | 131 |
| Spiral Welded Pipe | Ø273 × 7 mm | Q235B | $522 | 33 |
| Spiral Welded Pipe | Ø273 × 8 mm | Q235B | $522 | 100 |
| Spiral Welded Pipe | Ø325 × 5 mm | Q235B | $522 | 29 |
| Spiral Welded Pipe | Ø325 × 6 mm | Q235B | $522 | 73 |
| Spiral Welded Pipe | Ø325 × 7 mm | Q235B | $522 | 80 |
| Spiral Welded Pipe | Ø325 × 8 mm | Q235B | $522 | 31 |
| Spiral Welded Pipe | Ø325 × 9 mm | Q235B | $522 | 2 |
| Spiral Welded Pipe | Ø325 × 10 mm | Q235B | $522 | 3 |
| Spiral Welded Pipe | Ø377 × 5 mm | Q235B | $519 | 14 |
| Spiral Welded Pipe | Ø377 × 6 mm | Q235B | $519 | 17 |
| Spiral Welded Pipe | Ø377 × 7 mm | Q235B | $522 | 15 |
| Spiral Welded Pipe | Ø377 × 8 mm | Q235B | $519 | 19 |
| Spiral Welded Pipe | Ø377 × 9 mm | Q235B | $519 | 11 |
| Spiral Welded Pipe | Ø377 × 10 mm | Q235B | $519 | 10 |
| Spiral Welded Pipe | Ø426 × 6 mm | Q235B | $519 | 13 |
| Spiral Welded Pipe | Ø426 × 7 mm | Q235B | $519 | 23 |
| Spiral Welded Pipe | Ø426 × 8 mm | Q235B | $519 | 17 |
| Spiral Welded Pipe | Ø426 × 9 mm | Q235B | $519 | 33 |
| Spiral Welded Pipe | Ø426 × 10 mm | Q235B | $519 | 18 |
| Spiral Welded Pipe | Ø478 × 5 mm | Q235B | $519 | 16 |
| Spiral Welded Pipe | Ø478 × 6 mm | Q235B | $519 | 7 |
| Spiral Welded Pipe | Ø478 × 7 mm | Q235B | $519 | 9 |
| Spiral Welded Pipe | Ø478 × 9 mm | Q235B | $519 | 11 |
| Spiral Welded Pipe | Ø478 × 10 mm | Q235B | $519 | 34 |
| Spiral Welded Pipe | Ø529 × 5 mm | Q235B | $519 | 9 |
| Spiral Welded Pipe | Ø529 × 6 mm | Q235B | $519 | 37 |
| Spiral Welded Pipe | Ø529 × 7 mm | Q235B | $519 | 24 |
| Spiral Welded Pipe | Ø529 × 8 mm | Q235B | $519 | 32 |
| Spiral Welded Pipe | Ø529 × 9 mm | Q235B | $519 | 11 |
| Spiral Welded Pipe | Ø529 × 10 mm | Q235B | $519 | 24 |
| Spiral Welded Pipe | Ø630 × 5 mm | Q235B | $519 | 9 |
| Spiral Welded Pipe | Ø630 × 6 mm | Q235B | $519 | 15 |
| Spiral Welded Pipe | Ø630 × 7 mm | Q235B | $519 | 14 |
| Spiral Welded Pipe | Ø630 × 9 mm | Q235B | $519 | 13 |
| Spiral Welded Pipe | Ø630 × 10 mm | Q235B | $519 | 20 |
| Spiral Welded Pipe | Ø720 × 7 mm | Q235B | $519 | 5 |
| Spiral Welded Pipe | Ø720 × 8 mm | Q235B | $519 | 7 |
| Spiral Welded Pipe | Ø720 × 9 mm | Q235B | $519 | 15 |
| Spiral Welded Pipe | Ø720 × 10 mm | Q235B | $519 | 7 |
| Spiral Welded Pipe | Ø720 × 11 mm | Q235B | $519 | 5 |
| Spiral Welded Pipe | Ø820 × 5 mm | Q235B | $519 | 4 |
| Spiral Welded Pipe | Ø820 × 8 mm | Q235B | $519 | 3 |
| Spiral Welded Pipe | Ø820 × 9 mm | Q235B | $519 | 3 |
| Spiral Welded Pipe | Ø820 × 11 mm | Q235B | $519 | 3 |
| Spiral Welded Pipe | Ø1020 × 9 mm | Q235B | $519 | 1 |
| Spiral Welded Pipe | Ø1020 × 10 mm | Q235B | $519 | 3 |
| Spiral Welded Pipe | Ø1020 × 11 mm | Q235B | $519 | 7 |
| Spiral Welded Pipe | Ø1220 × 8 mm | Q235B | $519 | 4 |
Showing 51 of 51 listed sizes. Price range USD 519–522 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.