Two processes under one roof — high-frequency ERW for thin-wall small bore (fire fighting, water, gas, structure) and JCOE longitudinal submerged-arc welding for heavy-wall high-pressure lines up to 50 mm.
ERW (high-frequency welding): strip is progressively rolled into a cylinder, the edges are heated to melting by high-frequency current and forged together by squeeze rolls, then sized, straightened and cut to length. No filler metal, narrow weld, small heat-affected zone and high output — the workhorse below DN600.
JCOE: plate is edge-milled, pre-bent, pressed into a J shape, closed into an O, then welded inside and out by submerged arc, expanded and hydro-tested. Using plate rather than narrow strip allows 50 mm wall and DN1400, with pressure capability close to seamless.
| Standards | GB/T 3091 · GB/T 13793 · API 5L · ASTM A53 / A135 · EN 10219 |
| Outside diameter | DN15 – DN600（Φ21.3 – Φ610 mm） |
| Wall thickness | 1.8 – 20 mm |
| Length | 6 m / 12 m / cut to length |
| Steel grade | Q235B · Q355B · Gr.B – X42 |
| Finish | Bare · Hot-dip galvanized · Plastic-coated (fire red) · 3PE |
| Joints | Threaded · Grooved coupling · Welded · Flanged |
| Typical use | Fire sprinkler · Building water · LP gas · Scaffolding · Structure |
| Standards | GB/T 9711 · API 5L (PSL1 / PSL2) · EN 10217 · ASTM A53 |
| Outside diameter | DN400 – DN1400（Φ406 – Φ1420 mm） |
| Wall thickness | 6 – 50 mm |
| Length | 6 – 12 m |
| Steel grade | L245 – L485（Gr.B – X70） |
| Welding | Double-sided SAW + full-body expansion + hydro test |
| Typical use | HP oil & gas trunk lines · HP water · Structural piles |
Galvanized or plastic-coated per GB 50084, DN50–DN200 most common.
Risers and branches, galvanized or epoxy-lined.
Domestic and district gas lines, often to EN 10219.
Q235B / Q355B structural tube, galvanized.
JCOE with PSL2 and 3PE, 100% NDE.
Penstocks and pump-station piping.
ERW welds strip with high-frequency current — fast and economical for thin wall up to DN600; JCOE presses plate into a J shape and welds inside and out with submerged arc, reaching 50 mm wall and higher pressure for trunk lines.
Per GB 50084 and GB/T 3091: hot-dip galvanized ERW DN50–DN200 (zinc ≥300 g/m²) is standard; plastic-coated (red) or epoxy-lined for corrosive sites; above 1.6 MPa use heavier wall or seamless.
Yes — EN 10219, ASTM A53, A135 for ERW; EN 10217, API 5L PSL1/PSL2, ASTM A53 for JCOE. Third-party inspection (SGS/BV/TÜV) can be arranged at extra cost.
Replace with our ERW high-frequency mill or the JCOE forming press.
Replace with end facing/beveling, end grinding, hydrostatic test or UT.
Replace with a site photo where our straight-seam pipe serves fire, water or structural duty.
Technical proposal and quotation within one working day.
