Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 6728-2002 Cold Formed Steel Hollow Sections for General Structure - Dimensions, Shapes, Weight and Permissible Deviations, and the following main changes have been made with respect to GB/T 6728-2002:
——The standard name is modified;
——Relevant requirements for section tube are deleted;
——Specifications of thin-wall sectional steel are added;
——Relevant requirements for edge verticality are added;
——Relevant requirements for bending are added;
——Relevant technical requirements are added.
This standard is proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB/T 6728-1986, GB/T 6728-2002.
Cold Forming Hollow Sectional Steel for General Structure
1 Scope
This standard specifies the order contents; classification and code; section, dimension and permissible deviations; length and permissible deviation; shape; weight and permissible deviation; technical requirements and marking example of cold forming hollow sectional steel for general structure.
This standard is applicable to the circular, rectangular and square cold forming hollow sectional steel (hereafter referred to as "sectional steel") made of cold-rolled or hot-rolled steel sheet and strip by the continuous roller cold forming units, as well as the continuously hot-dip coated sectional steel, but not applicable to the sectional steel produced by methods such as drawing, stamping and bending and those made of galvanized steel plate and strip by cold forming and welding forming.
As for the sectional steel specified in this standard, high frequency resistance welding method is mainly adopted; argon arc welding or other welding methods may also be adopted.
2 Normative References
The following referenced document is indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6725 General Requirements of Cold Forming Steel Sections
3 Order Contents
The order contract or order based on this standard shall include the following information:
a) Standard number;
b) Product name;
c) Designation;
d) Delivery weight;
e) Dimension and shape;
f) Special requirements.
4 Classification and Code
Sectional steel is classified into square, rectangular and circular shapes, and their codes are as follows:
3) Circular sectional steel, circular tube for short, coded as: Y (or Φ).
5 Section, Dimension and Permissible Deviations
5.1 See Figure 1 for the sectional drawing of square sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 1.
5.2 See Figure 2 for the sectional drawing of rectangular sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 2.
5.3 See Figure 3 for the sectional drawing of circular sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 3.
5.4 The sectional dimension, sectional area, permissible deviation, theoretical weight and sectional characteristics of thin-wall sectional steel may be in accordance with the relevant requirements of GB 50018.
5.5 As required by the demander, it is allowed to provide the sectional steel whose dimension is not listed in Tables 1, 2 and 3, and its permissible dimension deviation shall comply with the deviation of next smaller size in the table; its sectional characteristics may be calculated in accordance with Annex A.
5.6 As for the permissible deviation for wall thickness of sectional steel, when wall thickness is ≤10mm, the permissible deviation shall not exceed ±10% of nominal wall thickness; when wall thickness is >10mm, the permissible deviation shall be ±8% of wall thickness.
5.7 The deviation of sectional steel's bending angle θ shall not be greater than ±1.5° and see Figure 6 for the measuring method.
Theoretical Weight and Sectional Characteristics of Square Sectional Steel
Foreword ii 1 Scope 2 Normative References 3 Order Contents 4 Classification and Code 5 Section, Dimension and Permissible Deviations 6 Length and Permissible Deviation 7 Shape 8 Weight and Permissible Deviation 9 Technical Requirements 10 Marking Example Annex A (Informative) Formula to Calculate Sectional Characteristics Bibliography
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 6728-2002 Cold Formed Steel Hollow Sections for General Structure - Dimensions, Shapes, Weight and Permissible Deviations, and the following main changes have been made with respect to GB/T 6728-2002:
——The standard name is modified;
——Relevant requirements for section tube are deleted;
——Specifications of thin-wall sectional steel are added;
——Relevant requirements for edge verticality are added;
——Relevant requirements for bending are added;
——Relevant technical requirements are added.
This standard is proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB/T 6728-1986, GB/T 6728-2002.
Cold Forming Hollow Sectional Steel for General Structure
1 Scope
This standard specifies the order contents; classification and code; section, dimension and permissible deviations; length and permissible deviation; shape; weight and permissible deviation; technical requirements and marking example of cold forming hollow sectional steel for general structure.
This standard is applicable to the circular, rectangular and square cold forming hollow sectional steel (hereafter referred to as "sectional steel") made of cold-rolled or hot-rolled steel sheet and strip by the continuous roller cold forming units, as well as the continuously hot-dip coated sectional steel, but not applicable to the sectional steel produced by methods such as drawing, stamping and bending and those made of galvanized steel plate and strip by cold forming and welding forming.
As for the sectional steel specified in this standard, high frequency resistance welding method is mainly adopted; argon arc welding or other welding methods may also be adopted.
2 Normative References
The following referenced document is indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6725 General Requirements of Cold Forming Steel Sections
3 Order Contents
The order contract or order based on this standard shall include the following information:
a) Standard number;
b) Product name;
c) Designation;
d) Delivery weight;
e) Dimension and shape;
f) Special requirements.
4 Classification and Code
Sectional steel is classified into square, rectangular and circular shapes, and their codes are as follows:
1) Square sectional steel, square tube for short, coded as: F;
2) Rectangular sectional steel, rectangular tube for short, coded as: J;
3) Circular sectional steel, circular tube for short, coded as: Y (or Φ).
5 Section, Dimension and Permissible Deviations
5.1 See Figure 1 for the sectional drawing of square sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 1.
5.2 See Figure 2 for the sectional drawing of rectangular sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 2.
5.3 See Figure 3 for the sectional drawing of circular sectional steel; its sectional dimension, permissible deviation, sectional area, theoretical weight and sectional characteristics shall meet the requirements of Table 3.
5.4 The sectional dimension, sectional area, permissible deviation, theoretical weight and sectional characteristics of thin-wall sectional steel may be in accordance with the relevant requirements of GB 50018.
5.5 As required by the demander, it is allowed to provide the sectional steel whose dimension is not listed in Tables 1, 2 and 3, and its permissible dimension deviation shall comply with the deviation of next smaller size in the table; its sectional characteristics may be calculated in accordance with Annex A.
5.6 As for the permissible deviation for wall thickness of sectional steel, when wall thickness is ≤10mm, the permissible deviation shall not exceed ±10% of nominal wall thickness; when wall thickness is >10mm, the permissible deviation shall be ±8% of wall thickness.
5.7 The deviation of sectional steel's bending angle θ shall not be greater than ±1.5° and see Figure 6 for the measuring method.
Keys:
B——The side length;
t——The wall thickness;
R——The outer arc radius.
Figure 1 Square Sectional Steel
Table 1 Sectional Dimension, Permissible Deviation, Sectional Area,
Theoretical Weight and Sectional Characteristics of Square Sectional Steel
Contents of GB/T 6728-2017
Foreword ii
1 Scope
2 Normative References
3 Order Contents
4 Classification and Code
5 Section, Dimension and Permissible Deviations
6 Length and Permissible Deviation
7 Shape
8 Weight and Permissible Deviation
9 Technical Requirements
10 Marking Example
Annex A (Informative) Formula to Calculate Sectional Characteristics
Bibliography
