GB/ T 6728-2002 Cold formed steel hollow sections for general structure
The standard is applicable to round, rectangular and square cold forming hollow sectional steel made of cold-rolled or hot-rolled steel plates, sheets and strips on continuous roll cold forming units. It is also applicable to continuous hot-dip plated sectional steel. However, it is not applicable to sectional steel made by drawing, stamping, bending, etc., and sectional steel made of galvanized steel plates, sheets and strips which are cold-formed and welded.
The standard corresponds to EN10219-2—1997 and ISO 4019:1982. Cold-formed steel is widely used in the production of structural parts and auxiliary parts, such as construction, railway vehicles, automobiles and ships.
Tolerance of Wall Thickness :
Not more than ±10% of the specified wall thickness when the wall thickness is ≤10mm, and not more than ±8% of the specified wall thickness when the wall thickness is ≥ 10mm.
Tolerance of Twist:
Twist tolerance of cold-formed steel hollow sections must not more than ±1.5%.
Tolerance of Length:
Grade | Length(mm) | Tolerance(mm) |
Ordinary level | 4000-12000 | +70 0 |
Precision level | 4000-6000 | +5 0 |
>6000-12000 | +10 0 |
Tolerance of R-corner:
Wall Thickness(t/mm) | R-corner | |
Carbon steel（σs≤320MPA） | Low-alloy steel（σs>320MPA） | |
t≤3 | 1.0-2.5t | 1.5-2.5t |
3<t≤6 | 1.5-2.5t | 2.0-3.0t |
6<t≤10 | 2.0-3.0t | 2.0-3.5t |
t>10 | 2.0-3.5t | 2.5-4.0t |
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