GB/T 706-1988 Hot Rolled Steel Angles Dimensions,Shape,Weight and Tolerances
This GB/T 706-1988 standard specifies the size, shape, weight, and tolerance for hot rolled steel angles. Hot rolled steel angles are widely used for many applications, such as various structures and engineering projects. This standard specifies the overall and length dimensional present, weight and dimensional tolerances, angles and corner radius, length and corner radius tolerances, marked length and surface quality requirements etc.
Dimensions
Hot rolled steel angles can be supplied in two types, common steel angles and unequal steel angles. Common steel angles are divided into three size categories small (25mm or less) medium (25-125mm) and large (125-250mm). Unequal steel angles are divided into two size categories small (25-75mm) and large (75-200mm). The length of common steel angles range from 4m-12m; the length of unequal steel angles range from 5m-12m. The actual size of angles depending on different thickness, which is divided into an L section and a T section.
Weight
The theoretical mass computed from the set of dimensions (length, width, thickness) for equal angles, unequal angles and for any sectional shape can be determined by multiplying the volume by the density of the supplied steel. The actual shipped weight of the steel angles may differ from the theoretical mass due to tolerances and the actual physical characteristics of the steel used in the hot rolling process. The allowable tolerances apply not only to the theoretical mass but also to the actual physical size within which the product can vary.
Angles and Corner Radius
Corner radius is the radius of the curvature of the corner of the material. The corner radius should comply with GB/T 5114 or according to customer requirements. The corner radius for equal angles is 1.5 times the size across the corner; for unequal angles, the corner radius does not exceed 1.5 times the size across the corner.
Length and Corner Radius Tolerances
The allowable length and corner radius tolerances for hot rolled steel angles shall be in accordance with Table 1.
Surface Quality Requirements
All surfaces of hot rolled steel angles should be free from defects such as scratches, rust, oil stains and other foreign matter. If the material is pickled, the residues of the pickling process should not be removed. The surfaces should be even and flat, and the edge should be well formed.
Marked Length
Marked lengths of hot rolled steel angles shall comply with the range specified in Table 2.
Table 1 Length and Corner Radius Tolerances
Size(mm) Corner radius(mm) Length tolerance(mm)
25-35 0.5 +/-5
35-50 0.6 +/-6
50-150 1 +/- 6
150-250 1.5 +/- 8
Table 2 Marked Length
Size(mm) Tolerance(mm) Length(m)
20-65 +/-3 4-5
65-150 +/-4 6-12
150-200 +/-5 6-12
200-250 +/-6 6-9
