1.Double-sided submerged arc welding — inside and outside passes guarantee full penetration and base-metal-equivalent strength.
2.Short weld seam — roughly half the seam length of spiral pipe at equal OD, with correspondingly lower defect risk and residual stress.
3.Tight tolerances — mechanical expanding delivers low ovality and uniform wall thickness for efficient field alignment and automatic welding.
4.Large OD & heavy wall — covers 400–1,600 mm OD up to 60 mm WT at high steel grades, far beyond the reach of ERW pipe.
5.Full traceability — 100% seam NDT, individual hydro-test and heat/lot traceability, with PSL2 supplementary requirements available.
LSAW (Longitudinal Submerged Arc Welded) steel pipe is manufactured from a single medium-heavy steel plate. After levelling, edge milling, pre-bending and JCOE forming, the seam is welded by submerged arc welding first from the inside and then from the outside, producing a full-penetration weld whose mechanical properties match the base metal. Mechanical expanding after forming ensures low out-of-roundness, uniform wall thickness and tight dimensional tolerances.
Compared with spiral welded pipe (SSAW/HSAW) of the same diameter, LSAW pipe has a shorter weld seam, lower residual stress and higher pressure-containing capacity, making it the preferred choice for high-grade, heavy-wall trunk pipelines and critical pressure service.
Products are supplied to API 5L / ISO 3183, GB/T 9711, ASTM A671 / A672 / A691, EN 10217 and AWWA C200, with 100% non-destructive seam inspection (RT/UT) and hydrostatic testing on every pipe. External anti-corrosion coatings (FBE, 3PE, 3PP) and internal linings (epoxy, cement mortar) are available on request.
1.Double-sided submerged arc welding — inside and outside passes guarantee full penetration and base-metal-equivalent strength. 2.Short weld seam — roughly half the seam length of spiral pipe at equal OD, with correspondingly lower defect risk and residual stress. 3.Tight tolerances — mechanical expanding delivers low ovality and uniform wall thickness for efficient field alignment and automatic welding. 4.Large OD & heavy wall — covers 400–1,600 mm OD up to 60 mm WT at high steel grades, far beyond the reach of ERW pipe. 5.Full traceability — 100% seam NDT, individual hydro-test and heat/lot traceability, with PSL2 supplementary requirements available.
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