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The pipe diameter and wall thickness diameter structure weld

The pipe diameter and wall thickness diameter structure welded steel pipe

Keywords: welded steel pipe

A structure with high strength weathering welded steel pipe (YB / T 4112-2002) provides high strength weathering of welded steel pipe Q300GNH \ Q325GNH and Q355GNH three grades. The standards listed in the three grades of steel pipes for civil construction scaffolding tower, pillar grid structure.

Second, the structure required weather with high strength welded steel pipe (YB / T 4112-2002) steel pipe diameter and wall thickness of three accuracy class as follows:

Outside diameter: outer diameter precision steel pipe D1

An outer diameter of the higher accuracy of a steel pipe D2

The outside diameter of ordinary precision steel pipe D3

Wall thickness: Wall thickness precision steel pipe S1

Wall thickness of the high accuracy of a steel pipe S2

The wall thickness of ordinary precision steel pipe S3

Third, the outer diameter of the tube wall thickness allowable deviation shall comply with the provisions of Table 1.1 and Table 1.2. Between consultation and specified in the contract, to supply steel pipe tolerances. The level of precision of the diameter, wall thickness should be specified in the contract, not indicated by ordinary accuracy supplier, the ordinary precision code may be omitted.

The outer diameter of the tube allows deviation Table 1.1

Outer diameter D (mm)	The size allowable deviation (mm)
Outer diameter D (mm)	Ordinary accuracy D3	Higher accuracy D2	High-precision D1
21-30	± 0.50	± 0.25	± 0.10
> 30-40	± 0.50	± 0.30	± 0.15
> 40-50	± 0.50	± 0.35	± 0.20
> 50-168	± 1.0% D	± 0.8% D	± 0.5% D

Steel pipe wall thickness allows deviations in Table 1.2

Wall thickness S (mm)	The size allowable deviation (mm)
	The ordinary precision of S3	High precision S2	High-precision S1
2.0	± 0.18	± 0.15	+0.07 -0.13
2.2		± 0.16
2.5	± 0.20	± 0.17	+0.08 -0.16
2.8		± 0.18
3.0
3.2	± 0.25	± 0.20	+0.10 -0.20
3.5
4.0		± 0.22
4.5-5.5	± 0.29	± 0.25	± 0.20
> 5.5-7.0	± 0.32	± 0.29	± 0.25