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 was 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).
Seamless hot-rolled square and rectangular steel tubes for structure
1 Scope
This standard specifies the order contents, dimensions, shapes and weights, technical requirements, inspection and test methods, inspection rules, and packaging, marking and quality certificate of seamless hot-rolled square and rectangular steel tubes for structure.
This standard applies to seamless hot-rolled square and rectangular steel tubes for structure.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.9 Iron, steel and alloy - Determination of aluminium content - Chrom azurol S photometric method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content
GB/T 223.14 Methods for chemical analysis of iron, steel and alloy - The n-benzoyl-n-phenylhydroxylamine extraction photometric method for the determination of vanadium content
GB/T 223.17 Methods for chemical analysis of iron, steel and alloy - The diantipyrylmethane photometric method for the determination of titanium content
GB/T 223.19 Methods for chemical analysis of iron steel and alloy - The neocuproine-chloroform extraction photometric method for the determination of copper content
GB/T 223.23 Iron, steel and alloy - Determination of nickel content - The dimethylglyoxime spectrophotometric method
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method
GB/T 223.37 Methods for chemical analysis of iron, steel and alloy - The indophenol blue photometric methods for the determination of nitrogen content after distillation separation
GB/T 223.40 Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.62 Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus content
GB/T 223.63 Methods for chemical analysis of iron, steel and alloy - The sodium (potassium) periodate photometric method for the determination of manganese content
GB/T 223.72 Iron steel and alloy - Determination of sulfur content - Gravimetric method
GB/T 223.81 Iron steel and alloy - Determination of total aluminum and total boron contents - Microwave digestion-inductively coupled plasma mass spectrometric method
GB/T 223.86 Steel and iron - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 699 Quality carbon structure steels
GB/T 700 Carbon structural steels
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2102 Acceptance, packing, marking and quality certification of steel pipe
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 3077 Alloy structure steels
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 10561-2005 Steel - Determination of content of nonmetallic inclusions - Micrographic method using standards diagrams
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
GB/T 20123 Steel and iron - Determination of total carbon and sulfur content - Infrared absorption method after combustion in an induction furnace (routine method)
GB/T 20124 Steel and iron - Determination of nitrogen content - Thermal conductimetric method after fusion in a current of inert gas (routine method)
GB/T 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method
YB/T 4149 Continuously cast round billet for seamless steel tube rolling
YB/T 5221 Alloy structure steel round tube blank hot rolled and forged for making seamless tube
YB/T 5222 Quality hot rolled and forged carbon structural steel round tube blank
3 Order contents
The contract or order for ordering steel tubes according to this standard shall include the following contents:
a) Standard No.;
b) Product name;
c) Grade and quality grade of steel (if applicable);
d) Number of ordering (total weight or total length);
e) Dimensions (side length × side length × wall thickness, mm);
f) Delivery state;
g) Special requirements.
4 Dimensions, shapes and weights
4.1 Dimensions and shapes
The shapes of the square and rectangular steel tubes shall meet the requirements of Figures 1 and 2 respectively. The nominal dimension of square steel tubes is: side length 40mm×40mm~500mm×500mm, wall thickness 3.0mm~60mm; dimension range of rectangular steel tube: side length 50mm×30mm~600mm×400mm, wall thickness 3.0mm~60mm.
Keys:
X, Y——X and Y axes respectively;
A——side length;
S——wall thickness;
R——round radius.
Figure 1 Square steel tube Keys:
X, Y——X and Y axes respectively;
A, B——the lengths of long side and short side respectively;
S——wall thickness;
R——round radius.
Figure 2 Rectangular steel tube
4.2 Permissible dimension deviation
4.2.1 The permissible dimension deviation of steel tube shall be in accordance with those specified in Table 1. When the permissible dimension deviation grade is not noted in the contract by the purchaser, the permissible dimension deviation of steel tube shall meet the requirements of common dimensional accuracy.
4.2.2 As required by the purchaser, steel tube beyond the permissible dimension deviation specified in Table 1 may be supplied upon negotiation between the supplier and the purchaser.
Table 1 Permissible dimension deviation of steel tube In: mm
Dimension Permissible deviation
Common grade High grade
Side lengths A and B All ±1%A, ±1%B ±0.75%A, ±0.75%B
Wall thickness, S 3.0~20 ±12.5%S ±10%S
>20 ±10%S and ≤ ±5 ±8%S and ≤ ±4
4.3 Side convex-concave degree
The side convex-concave degree of the square steel tube shall not be greater than 1%A; the convex-concave degrees of long side and short side of rectangular steel tube shall not be greater than 1%A and 1%B respectively.
4.4 Round radius
The round radius (R) of end surface for steel tube shall not be greater than the nominal wall thickness (S) by 3 times.
4.5 Curvature
The curvature of tube per meter shall not be greater than 3.0mm; and the curvature of the full length shall not be greater than 0.2% of the full length. As required by the purchaser and indicated in the contract upon the agreement between the supplier and the purchaser; the steel tube with higher curvature may be supplied.
4.6 Twisting value
The steel tube shall be free from visible twist. The twisting value of the full length of the steel tube shall not be greater than (2+0.5×L/1,000) mm.
Note: L is the length of steel tube, mm;
4.7 Perpendicularity of side
The perpendicularity of the adjacent sides of the steel tube shall be 90°±1°.
4.8 Length
4.8.1 Random length
The random length of steel tube is 2,000~12,000mm. As required by the purchaser and indicated in the contract upon the agreement between the supplier and the purchaser, the steel tube with the length beyond the specification may be supplied.
4.8.2 Cut length and multiple length
4.8.2.1 As required by the purchaser and indicated in the contract upon the agreement between the supplier and the purchaser, steel tubes may be delivered in cut length or multiple length.
4.8.2.2 The cut length and multiple length shall be within the random length. The permissible deviation of the cut length is■(+15@ 0)mm; while that of the total multiple length is ■(+20@ 0)mm; each multiple length shall keep a notch allowance of 5mm~10mm.
4.9 End shape
The end surface of steel tube at both ends shall be vertical to steel tube axes and notch burrs shall be cleared away.
4.10 Weight
4.10.1 Delivery weight
Steel tubes shall be delivered according to the actual weight. If indicated in the contract, delivery may be carried out according to theoretical weight (density of steel is 7.85kg/dm3)
4.10.2 Permissible deviation of weight
As required by the purchaser and indicated in the contract upon the agreement between the supplier and the purchaser, the deviation between the theoretical weight and actual weight of the delivered steel tubes shall meet the following requirements:
a) Single steel tube: ±10%;
b) Steel tubes of minimum 10t in each batch: ±7.5%.
Foreword II
1 Scope
2 Normative references
3 Order contents
4 Dimensions, shapes and weights
5 Technical requirements
6 Inspections and test methods
7 Inspection rules
8 Packaging, marking and quality certificate
