Pierced and rolled from a solid billet in one continuous process — no longitudinal weld anywhere along the length. For high pressure, boilers, hydraulics and machined parts where a weld seam is not acceptable.
A solid billet is heated to about 1200 °C in a rotary hearth furnace, pierced into a hollow shell, reduced and elongated in a mandrel mill, sized, straightened, cropped and inspected. The metal deforms continuously with no welding step, giving a uniform structure and high pressure capacity.
The trade-off is limited diameter (hot-rolled up to Φ630) and wider wall tolerance (typically ±12.5 %), at a higher price. Seamless is not universal: for low-pressure large-diameter transport welded pipe is more economical.
| Outside diameter | Hot-rolled Φ57–Φ630 mm · Cold-drawn Φ10–Φ89 mm |
| Wall thickness | 3 – 40 mm |
| Length | 6 – 12 m |
| Standards | GB/T 8163 (fluid) · GB/T 8162 (structural) · GB/T 3087 / 5310 (boiler) · ASTM A106 B · ASTM A53 B · A179 |
| Grades | 10# · 20# · 45# · 16Mn(Q345) · Alloy steel |
| Process | Billet heating → Piercing → Rolling → Sizing → Straightening |
| Wall tolerance | Typically ±12.5 % (tighter on cold-drawn) |
| Inspection | Hydrostatic test · Eddy current · UT · Spectrometry |
| Typical use | Fluid transfer · Boilers & heat exchangers · Hydraulics · Machining |
GB/T 8163 fluid tube for water, oil and gas.
GB/T 3087 / 5310 and ASTM A179 heat-exchanger tube.
Precision cold-drawn tube, smooth bore and stable size.
Blanks for sleeves, rollers and cylinders.
Pressure piping, alloy grade chosen by medium.
Dedicated shells such as 34CrMo4.
Yes — a solid billet is heated, pierced, rolled and sized in one continuous process, so there is no weld along its length. The trade-off is limited diameter and wider wall tolerance (typically ±12.5%).
Seamless for high pressure (>6.4 MPa), hazardous media, machining or cyclic loads; spiral or straight-seam welded for large diameter (>Φ630), low pressure and cost-sensitive projects.
Every batch ships with a mill test certificate (heat number, chemical composition, mechanical properties). SGS / BV / TÜV witness or export inspection can be arranged in advance.
Replace with our piercing mill, pipe mill or cold-drawing bench — a genuine seamless workshop shot matters most.
Replace with end-face inspection, wall-thickness gauging, eddy-current or UT.
Replace with a photo of our seamless pipe in high-pressure, boiler or mechanical service.
Technical proposal and quotation within one working day.
