Diameter DN15–DN3800, wall 1.8–40 mm. Standards GB/T 9711, GB/T 3091, GB/T 8163, API 5L, ASTM A106 — with specification tables, application notes and the five questions buyers ask most.
Hot-rolled steel strip is formed continuously by a spiral bending unit and welded on both sides by submerged-arc welding in one pass. Because the weld is spiral-shaped, pressure is distributed evenly around the pipe, and one width of strip can produce many different diameters — that is why spiral pipe dominates DN500 and above.
Best for: buried water mains, drainage, oil & gas transmission, piling casings and outer casing pipes for insulated pipelines. Lengths up to 14 m mean fewer site welds and faster installation.
| Item | SSAW Spiral Pipe |
|---|---|
| Outside diameter | DN200 – DN3800（Φ219 – Φ3820 mm） |
| Wall thickness | 5 – 25.4 mm (typical 5 – 20 mm) |
| Length | 6 – 14.5 m, fixed or multiple lengths |
| Steel grade | Q195 – Q460 ｜ L175 – L485 ｜ X42 – X80 |
| Standards | GB/T 9711（PSL1 / PSL2）· SY/T 5037 · API 5L · EN 10217 / EN 10219 |
| Ends | Plain / beveled / with flange or coupling |
| Testing | Hydrostatic test, UT, X-ray, tensile & impact test |
Our spiral lines feed directly into 3PE / TPEP / FBE coating and cement-mortar lining lines, so base pipe and coating are finished in one plant — no second lifting, no transport between suppliers, one responsible party for quality.
ERW (Electric Resistance Welding): high-frequency current melts the strip edges and they are pressed together — no filler metal, a very narrow weld bead, excellent dimensional accuracy and surface. ERW is the workhorse for small and medium diameters, and is also the base pipe of hot-dip galvanized pipe to GB/T 3091.
JCOE (LSAW): a steel plate is pressed step by step (J–C–O) into a tube, then welded inside and out by submerged-arc welding and expanded for roundness. JCOE serves high-pressure trunk lines where large diameter AND high pressure meet.
| Item | ERW Straight-Seam | JCOE (LSAW) |
|---|---|---|
| Outside diameter | DN15 – DN600（Φ21.3 – Φ630 mm） | DN400 – DN1400（Φ406 – Φ1422 mm） |
| Wall thickness | 1.8 – 16 mm | 8 – 30 mm |
| Steel grade | Q195 – Q345 ｜ A ｜ B | X42 – X80 ｜ Q345 – Q460 |
| Standards | GB/T 3091 · API 5L · ASTM A53 / A135 · EN 10219 | GB/T 9711 · API 5L（PSL1 / PSL2） |
| Typical use | Water, gas, fire lines, scaffolding, structure | High-pressure oil & gas, road/river crossings |
1) Inside diameter: measure with a rod across the pipe — ovality matters for joint fit-up. 2) Weld seam: even bead, no undercut. 3) Mill certificates: heat number on the pipe must match the certificate. We welcome third-party inspection before shipment.
A solid round billet is pierced and rolled (hot-rolled, or cold-drawn for small sizes) into a pipe in one piece — there is no weld seam at all. That is why seamless pipe is the first choice for boilers, chemical lines and other high-pressure, high-temperature service.
Trade-off to know: seamless wall thickness tolerance is larger than welded pipe (typically ±12.5%), and big diameters get expensive. A common cost-saving combo is seamless where pressure is critical, welded elsewhere.
| Item | Seamless Pipe |
|---|---|
| Outside diameter | Φ57 – Φ630 mm (smaller sizes by cold drawing) |
| Wall thickness | 3 – 40 mm |
| Steel grade | 10# · 20# · 45# · 16Mn(Q345) · alloy steels |
| Standards | GB/T 8163 (fluids)· GB/T 8162 (structure)· GB/T 3087 / 5310 (boilers)· ASTM A106 B / A53 B / A179 |
| Typical use | Boilers, chemical & high-pressure lines, mechanical parts |
ERW base pipe is dipped in molten zinc, giving a bonded zinc layer inside and out that sacrifices itself to protect the steel. Standard finish for fire sprinkler and standpipe systems, water risers and outdoor supports, executed to GB/T 3091.
| Item | SSAW Spiral | ERW | JCOE LSAW | Seamless |
|---|---|---|---|---|
| Forming | Strip spiral-formed, SAW both sides | High-frequency resistance welding | Plate pressed J-C-O, SAW + expansion | Solid billet pierced & rolled |
| Diameter range | DN200–3800 | DN15–600 | DN400–1400 | Φ57–630 mm |
| Pressure capability | Medium–high, even stress | High, narrow weld | Highest for large diameter | Highest, no weld seam |
| Relative cost | Lowest at large diameter | Lowest at small diameter | High | Highest (large sizes) |
| Go-to use | Water/oil/gas mains, piling | Water, gas, fire, structure | High-pressure trunks, crossings | Boiler, chemical, machining |
Follow diameter and pressure. DN500 and above at medium pressure: spiral is the most economical. Small diameters, gas and fire lines: ERW (often galvanized). Large diameter plus high pressure (trunk lines, crossings): JCOE. Many real projects mix all three by section.
Yes — it is pierced and rolled from a solid billet in one piece, so there is no weld seam. Note that its wall-thickness tolerance (±12.5% typical) is wider than welded pipe; for critical lines we can select enhanced-tolerance tubes.
API 5L (PSL1/PSL2), EN 10217/10219, ASTM A53/A106/A135/A179, ISO 4437 and equivalents. Chinese GB/T 9711 aligns closely with API 5L; we ship with mill test certificates and full traceability by heat number.
Spiral pipe: fixed or multiple lengths up to 14.5 m — fewer site welds. ERW: standard 6 m or custom. Seamless: 6–12 m random or fixed. Tell us your handling limits (truck, container) and we optimize the length.
Yes — one plant finishes it all: cement-mortar lining, IPN8710, 3PE / TPEP / FBE external, polyurethane or steel-jacket insulation, plus flanges and fittings. One factory, one quality responsibility.
Technical proposal and quotation within one working day.
