GB/T 6723-2017 English PDF (GBT6723-2017)

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GB/T 6723-2017: Cold forming open section steel for general structure
GB/T 6723-2017
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.70
H 44
Replacing GB/T 6723-2008
Cold forming open section steel for general structure
ISSUED ON: MAY 31, 2017
IMPLEMENTED ON: DECEMBER 1, 2017
Issued by: General Administration of Quality Supervision, Inspection
and Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Normative references ... 4 
3 Order content ... 4 
4 Classification and code ... 4 
5 Cross-section size and allowable deviation ... 5 
6 Length and allowable deviation ... 28 
7 Shape ... 29 
8 Technical requirements ... 30 
9 Weight ... 30 
10 Marking examples ... 30 
Foreword
This Standard was drafted in accordance with the rules given in GB/T
1.1-2009.
This Standard replaces GB/T 6723-2008, Cold forming sectional steel - Open
sectional steel for general structure - Size, shape, weight and permissible
tolerances. Compared with GB/T 6723-2008, the main changes in this
Standard are as follows:
- modify the standard’s name;
- add the order content;
- add the product specifications;
- add equal curling angle steel;
- add technical requirements.
This Standard was proposed by China Iron and Steel Industry Association.
This Standard shall be under the jurisdiction of National Technical Committee
183 on Iron and Steel of Standardization Administration of China (SAC/TC
183).
The drafting organizations of this Standard: Metallurgical Industry Information
Standards Institute, Wuhan Iron and Steel Jiangbei Group Co., Ltd., Shanxi
Dingrong Cold-forming Steel Co., Ltd.
The drafters of this Standard: Wang Yujie, Zhu Shaowen, Sheng Zhenjian,
Song Yuguang, Liu Baoshi.
The previous versions of the standards which are replaced by this Standard
are:
- GB/T 6723-1986, GB/T 6723-2002, GB/T 6723-2008.
Cold forming open section steel for general structure
1 Scope
This Standard specifies the order content, classification, code, section size
and allowable deviation, length and allowable deviation, shape, technical
requirements, weight and marking examples of cold forming open section
steel for general structure.
This Standard is applicable to cold forming open section steel (hereinafter
referred to as section steel) which is produced on continuous roll cold
bending unit by cold-rolled or hot-rolled steel sheets.
2 Normative references
The following documents are indispensable for the application of this
document. For dated references, only the dated version applies to this
document. For undated references, the latest edition (including all
amendments) applies to this document.
GB/T 6725, General requirements of cold forming steel sections
3 Order content
The contract or order in accordance with this Standard shall include the
following contents:
a) Standard serial number;
b) product name;
c) designation;
d) delivery weight;
e) size and shape;
f) special requirements.
4 Classification and code
The section steels, according to their cross-section shapes, are divided into 9
types, and their codes are:
a) cold forming equal angle steel, JD;
b) cold forming unequal angle steel, JB;
c) cold forming equal channel steel, CD;
d) cold forming unequal channel steel, CB;
e) cold forming inside curling channel steel, CN;
f) cold forming outside curling channel steel, CW;
g) cold forming Z-shaped steel, Z;
h) cold forming curling Z-shaped steel, ZJ;
i) curling equal angle steel, JJ.
5 Cross-section size and allowable deviation
5.1 Cross-section shape and labeling of the section steel
The cross-section shape and labeling of the section steel are shown in Figure
1 ~ Figure 9. If it is negotiated between the supplier and the buyer and
indicated in the contract, the section steels, other than the cross-section
shapes which are listed in Figures 1 ~ Figure 9, can be supplied.
5.2 Size, theoretical weight, cross-section area and main parameters of
the section steel
Size, theoretical weight, cross-section area and main parameters of the
section steel are shown in Figure 1 ~ Figure 9. If it is negotiated between the
supplier and the buyer and indicated in the contract, the section steels, other
than the size which are listed in Figures 1 ~ Figure 9, can be supplied; the
parameters shall be negotiated between the supplier and the buyer.
5.4.3 When the nominal sizes of two free side lengths are equal, the actual
size difference shall not exceed 75% of the allowance. When the nominal
sizes of the two free side lengths are not equal, execute according to the
allowable deviation of the larger side length.
5.4.4 The allowable deviation of the wall thickness of the section of the steel
plate shall be in accordance with the corresponding standard of the steel
plate and steel strip that is used. The wall thickness reduction in the bending
angle region does not exceed 10% of the nominal wall thickness of the
section steel.
5.5 Allowable deviation of bending angle
The length allowable deviation of the bending angle shall comply with the
requirements of Table 13.
Table 13 -- Allowable deviation of bending angle
5.6 Measuring position
The size of the section steel shall be measured at not less than 100 mm from
the end.
6 Length and allowable deviation
6.1 The general length of section steel is 4 000 mm ~ 16 000 mm. If it is
negotiated between the supplier and the buyer and indicated in the contract,
section steels other than the above-mentioned specified length may also be
supplied.
6.2 When the steel is delivered in fixed-length or multiple-length, it shall be
indicated in the contract. When it is delivered in fixed-length or multiple-length,
the length allowable deviation shall comply with the provisions of Table 14. If
the fixed-length accuracy is not indicated in the contract, it shall be delivered
according to the ordinary fixed-length.
Shorter side length size mm Allowable deviation (°)