1. Core tolerance standards General wall thickness tolerance:
±12.5% (applicable to conventional wall thickness range).
Example:
Nominal wall thickness 10mm → Allowable range: 8.75–11.25mm;
Nominal wall thickness 20mm → Allowable range: 17.5–22.5mm.
Special requirements for weld area:
Wall thickness at weld allows for negative deviations but does not limit positive deviations (to ensure structural strength first)
2. Factors affecting tolerance
| Parameter | Tolerance Association Rules |
|---|---|
| Outer diameter | The larger the outer diameter, the looser the wall thickness tolerance control (for example, when the outer diameter is ≥219mm, the tolerance can be relaxed to ±15%) |
| Thickness to diameter ratio (t/D) | The smaller the ratio of wall thickness (t) to outer diameter (D), the stricter the tolerance requirement (thin-walled tubes require higher precision) |
| Production process | The tolerance control of submerged arc welded pipe (LSAW) is better than that of spiral welded pipe (SSAW), with the former having a typical tolerance of ±10%–12.5% |
3. Application Notes
Testing requirements:
The wall thickness of each steel pipe must be measured at 100mm from the pipe end, and the average value of four points must be taken;
Negative deviation control:
The local minimum wall thickness must not be less than 87.5% of the nominal value (avoid weak bearing points);
Special orders:
For severe working conditions (such as offshore platform pile foundations), a custom tolerance of ±10% can be negotiated, but additional costs are required.
