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GB/T 8162 Seamless Steel Tubes For Structural Purposes

Attention:     Issuing time:2019-05-28 21:57

 
GB/T 8162 -2018
Seamless steel tubes for structural purposes

 

1 Scope
This standard specifies the order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, and seamlessness of structural seamless steel tubes.
Sign and quality certificate.
This standard applies to seamless steel tubes for mechanical structures and general engineering structures.
 
 
2. Normative references
 
 
3. Ordering content
Contracts or orders for ordering steel pipes in accordance with this standard shall include the following:
a) standard number;
b) product name;
c) the grade of the steel, the quality grade should include the quality grade;
d) size specifications;
e) the quantity ordered (total weight or total length);
f) delivery status;
g) Special requirements.
 
 
4 size, shape and weight
4.1 outer diameter and wall thickness
The nominal outer diameter (D) and nominal wall thickness (S) of the steel pipe shall comply with the provisions of GB/T 1 7395. According to the requirements of the purchaser, other steel pipes of outer diameter and wall thickness can be supplied through negotiation between the supplier and the buyer.
4.2 Allowable deviation of outer diameter and wall thickness
4.2.2 The allowable deviation of the outer diameter of the steel pipe shall comply with the requirements of Table 1.
 
Table 1 Allowable deviation of outer diameter of steel pipe in millimeters
 
Steel pipe type Allowable deviation
Hot rolled (expanded) steel pipe ± 1% D or ±0. 5, whichever is the larger
Cold drawn (rolled) steel pipe ± 0.75 %D or ±0. 3, whichever is the larger
 
 
 
4.2.2 The allowable deviation of the wall thickness of the hot milk (expanded) steel pipe shall comply with the requirements of Table 2.
 
Table 2 Allowable deviation of wall thickness of hot rolled (expanded) steel pipe in millimeters
 
 

Steel pipe type Steel pipe nominal diameter D S/D Allowable deviation
Hot rolled  steel pipe ≤102 ±1 2. 5% S or ±0. 4, whichever is the larger
  >102 ≤0.05 ± 1 5 % S or ±0. 4, whichever is the larger
    >0. 05 〜0.10 ±1 2. 5% S or ±0. 4, whichever is the larger
    >0. 1 0 + 12. 5%S
- 1 0 % S
Cold drawn steel pipe   ± 1 5 % S
 
 
4.2.3 The allowable deviation of the wall thickness of the cold drawn (milk) steel pipe shall comply with the requirements of Table 3.
 
Table 3 Allowable deviation of cold-drawn (milk) steel pipe wall thickness in millimeters
 
Type of Steel pipe Steel pipe nominal wall thickness S Allowable deviation
Cold drawn steel pipe ≤3 (+1 5 % S,- 1 0 % s) Or ±0. 1 5, whichever is the larger
  > 3 〜 10 + 12. 5% S
- 1 0 %S
  > 1 0 ± 1 0 %S
 
 
 
4 . 2 . 4 According to the requirements of the purchaser, after consultation between the supplier and the buyer, and in the contract, the steel pipe with the allowable deviation of the dimensions specified in Table 1, Table 2 and Table 3 may be supplied.
 
4 . 3 length
4 . 3 . 1 normal length
The normal length of steel pipes is 3 000 mm to 12 000 mm. According to the requirements of the purchaser, steel pipes outside the normal length can be supplied through negotiation between the supplier and the buyer.
4 . 3 . 2 range length
According to the requirements of the purchaser, after consultation between the supplier and the buyer, and in the contract, the steel pipe can be delivered according to the length of the scope.
 
 
4 . 3 . 3 length and length
4. 3. 3. 1 According to the requirements of the purchaser, the supplier and the buyer shall negotiate and indicate in the contract that the steel pipe can be delivered according to the length of the fixed length or the length of the double.
4. 3. 3. 2 When the steel pipe is delivered in fixed length or multiple length, the length tolerance shall comply with the following requirements:
a) When the length of the fixed length or the length of the double length is not more than 6 000 m, the allowable deviation is (+30,0) mm;
b) When the length of the ruler or the length of the ruler is greater than 6 000 m, the allowable deviation is (+50,0) mm.
4. 3. 3. 3 When the steel pipe is delivered in multiple lengths, the length of each double length shall be set as follows:
a) When D≤159 mm, the remaining amount of the incision is 5 mm~10 mm;
b) When D >159 mm, the remaining allowance is 10 mm~15 mm.
Steel pipes of other incisions can be supplied through negotiation between the supplier and the buyer.
 
 
4 . 4 bending
4.4.1 The bending per meter of steel pipe shall comply with the requirements of Table 4.
 
Table 4 Bending degree of steel pipe
 
Steel pipe nominal wall thickness S/mm Bend per meter / (mm / m)
≤1 5 ≤1.5
> 1 5 〜 30 ≤2.0
> 3 0 or D ≥351 ≤3.0
 
 
 
4.4.2 The full-length bending of the steel pipe shall not exceed 0.15% of the total length of the steel pipe.
4. 5 Unroundness and uneven wall thickness
According to the requirements of the purchaser, the supplier and the buyer shall negotiate and indicate in the contract that the out-of-roundness and wall thickness of the steel pipe shall not exceed 80% of the nominal outer diameter tolerance and the nominal wall thickness tolerance respectively.
4 . 6 end shape
4.6.1 The steel pipe with a nominal outer diameter of not more than 60mm shall have a pipe end notching of more than 1.5 mm; for a steel pipe with a nominal outer diameter of more than 60 mm, the pipe end inclination shall not exceed 2.5% of the nominal outer diameter of the steel pipe, but the maximum shall be No more than 6 mm. The skew of the steel pipe is shown in Figure 1.
 


 
4 . 6 . 2 End cuts of steel pipes The burrs should be removed.
4 . 7 weight
4.7.1 The steel pipe is delivered according to the actual weight and can also be delivered according to the theoretical weight. The theoretical weight of the steel tube is calculated according to the provisions of GB/T 17395, and the density of the steel is 7.85 kg/dm3.
4 . 7 . 2 According to the requirements of the purchaser, the supplier and the buyer shall negotiate and indicate in the contract that the deviation between the theoretical weight of the delivered steel pipe and the actual weight shall comply with the following provisions:
a) Single steel pipe: ±10%;
b) Steel pipes with a minimum of 10 t per batch: ± 7.5 %.
 

 
5 Technical requirements
5. 1 Steel grade and chemical composition
5.1.1 The grade and chemical composition of the high-quality carbon structural steel (melting analysis) shall comply with the provisions of GB/T 699.
5.1.2 The grade and chemical composition of the low-alloy high-strength structural steel (melting analysis) shall comply with the requirements of Table 5. Except for quality class A, the carbon equivalent of each grade shall comply with the requirements of Table 6. The carbon equivalent (CEV) should be calculated from the smelting analysis component according to formula (1).
 
CEV = C + Mn/6 + (Cr + Mo + V) /5 + (Ni + Cu) /15 . . . . . . . . . . . . . . . . . . . . .(1)
 
5.1.3 Alloy structural steel grades and chemical composition (melting analysis) shall comply with the provisions of GB/T 3077.
5. 1. 4 According to the requirements of the purchaser, steel pipes of other grades or chemical compositions may be supplied through negotiation between the supplier and the buyer.
5 . 1 . 5 When the purchaser requests to perform a finished product analysis, it should be indicated in the contract. The allowable deviation of the chemical composition of the finished steel pipe shall comply with the provisions of GB/T 222.
 
Table 5 Grades and chemical compositions of low-alloy high-strength structural steel
 
Grade Quality level Chemical composition (mass fraction) %
C Si Mn P S Nb V Ti Cr Ni Cu N d Mo B Alse
Q345 A 0.20 0.50 1.70 0.035 0.035 - - - 0.30 0.50 0.20 0.012 0.10
B 0.035 0.035
C 0.030 0.030 0.07 0.15 0.20 0.015
D 0.18 0.030 0.025
E 0.025 0.020
Q390 A 0.20 0.50 1.70 0.035 0.035 0.07 0.20 0.20 0.30 0.50 0.20 0.015 0.10
B 0.035 0.035
C 0.030 0.030 0.015
D 0.030 0.025
E 0.025 0.020
Q420 A 0.20 0.50 1.70 0.035 0.035 0.07 0.20 0.20 0.30 0.80 0.20 0.015 0.20
B 0.035 0.035
C 0.030 0.030 0.015
D 0.030 0.025
E 0.025 0.020
Q460 C 0.20 0.60 1.80 0.030 0.030 0.11 0.20 0.20 0.30 0.80 0.20 0.015 0.20 0.005 0.015
D 0.030 0.025
E 0.025 0.020
Q500 C 0.18 0.60 1.80 0.025 0.020 0.11 0.20 0.20 0.60 0.80 0.20 0.015 0.20 0.005 0.015
D 0.025 0.015
E 0.020 0.010
Q550 C 0.18 0.60 2.00 0.025 0.020 0.11 0.20 0.20 0.80 0.80 0.20 0.015 0.30 0.005 0.015
D 0.025 0.015
E 0.020 0.010
Q620 C 0.18 0.60 2.00 0.025 0.020 0.11 0.20 0.20 1.00 0.80 0.20 0.015 0.30 0.005 0.015
D 0.025 0.015
E 0.020 0.010
Q690 C 0.18 0.60 2.00 0.025 0.020 0.11 0.20 0.20 1.00 0.80 0.20 0.015 0.30 0.005 0.015
D 0.025 0.015
E 0.020 0.010
a In addition to the Q345A and Q345B grades, the steel should contain at least one of the refined crystal elements Al, Nb, V, and T i . The supplier may add one or more of the refined crystal elements as needed, and the maximum value shall comply with the requirements in the table. When combined, Nb+ V + Ti< 0 . 2 2 %.
b For Q345, Q390, Q420 and Q460 grades, M〇+ ​​Cr< 0 . 3 0 %.
c When Cr and N i of each grade are used as residual elements, the content of Cr and Ni should be no more than 0.30%; when it is required to be added, the content should meet the requirements in the table or be determined by the supplier and the buyer.
d The supplier can ensure that the nitrogen content meets the requirements in the table, and the nitrogen content analysis is not performed. If alloying elements such as Al, Nb, V, and T i with nitrogen fixation are added to the steel, the nitrogen content is not limited, and the nitrogen content of the nitrogen should be indicated in the quality certificate.
e When all aluminum is used, the total aluminum content is Alt > 0. 0 2 0 %.
 
 
Table 6 Carbon equivalent
 
Grade Carbon quantity CEV (mass fraction) / %
Nominal wall thickness S < 16 mm Nominal wall thickness S > 16 mm ~ 30 mm Nominal wall thickness S > 3 0 mm
Hot rolled or normalized Quenching + tempering Hot rolled or normalized Quenching + tempering Hot rolled or normalized Quenching + tempering
Q 345 ≤0. 45 ≤0.47 ≤0.48
Q 390 ≤0. 46 ≤0.48 ≤0.49
Q 420 ≤0.48 ≤0.50 ≤0.48 ≤0.52 ≤0.48
Q 460 ≤0.53 ≤0.48 ≤0.55 ≤0.50 ≤0.55 ≤0.50
Q 500 ≤0.48 ≤0.50 ≤0.50
Q 550 ≤0.48 ≤0.50 ≤0.50
Q 620 ≤0.50 ≤0.52 ≤0.52
Q 690 ≤0.50 ≤0.52 ≤0.52
 
 
 
5 . 2 Manufacturing methods
5 . 2 . 1 steel smelting method
Steel should be smelted by electric arc furnace plus furnace refining or oxygen converter plus furnace refining method. After consultation between the supply and demand sides, other methods of higher requirements may also be used for smelting. When the purchaser specifies a certain smelting method, it should be indicated in the contract.
Manufacturing Method 5. 2.2 shell of
5. 2. 2. 1 Tube blanks can be manufactured by continuous casting, die casting or hot milk (forging).
5. 2. 2. 2 continuous casting tube blanks shall comply with the provisions of YB/T 4149; hot milk (forged) tube blanks shall comply with the provisions of YB/T 5221 or YB/T 5222; the molded tube blanks may refer to hot milk ( The implementation of the forging) tube blank.
5 . 2 . 3 manufacturing method of steel pipe
Steel pipes shall be manufactured by hot milk (expansion) or cold drawing (milk) without seaming. When the purchaser specifies a method to manufacture steel pipes, it should be indicated in the contract.
 
5 . 3 delivery status
5.3.1 Hot milk (expanded) steel pipes are delivered in hot milk (expanded) or heat treated condition. When the purchaser requests the heat treatment status, it shall be indicated in the contract.
5 . 3 . 2 Cold drawn (milk) steel pipes shall be delivered in an annealed or high temperature tempered condition. According to the requirements of the purchaser, after consultation between the supplier and the buyer, and in the contract, the cold drawn (milk) steel pipe can also be delivered in cold drawn (milk) or other heat treatment conditions.
 
 
5.4 Mechanical properties
5 . 4 . 1 tensile properties
5.4.1.1 For steel pipes of high quality carbon structural steel and low alloy high strength structural steel, the tensile properties in the delivery state shall comply with the requirements of Table 7.
5. 4. 1. 2 alloy structural steel pipe specimen blanks According to the recommended heat treatment system in Table 8, the tensile properties measured after the heat treatment is prepared shall comply with the requirements of Table 8.
5. 4. 1. 3 Cold drawing (milk) state The mechanical properties of the delivered steel pipe shall be determined by negotiation between the supplier and the buyer.
GB/T 8162—2018
 
Table 7 Mechanical properties of high quality carbon structural steel and low alloy high strength structural steel pipe
 
Grade quality level Tensile strength
Rm/M Pa
Lower yield strength MPa
Nominal wall thickness S
Elongation Impact test
≤1 6 mm >16 mm 〜
30 mm
〉 30 mm Temperature Absorb energy
10 ≥335 205 195 185 24
15 ≥375 225 215 205 22
20 ≥410 245 235 225 20
25 ≥450 275 265 255 18
35 ≥510 305 295 285 17
45 ≥590 335 325 315 14
20 Mn ≥450 275 265 255 20
25 Mn ≥490 295 285 275 18
Q 345 A 470〜 630 345 325 295 20
B + 20 34
C 21 0
D - 20
E - 40 27
Q 390 A 490〜 650 390 370 350 18
B + 20 34
C 19 0
D - 20
E - 40 27
Q 420 A 520〜 680 420 400 380 18
B + 20 34
C 19 0
D - 20
E - 40 27
Q 460 C 550〜 720 460 440 420 17 0 34
D - 20
E - 40 27
Q 500 C 610〜 770 500 480 440 17 0 55
D - 20 47
E - 40 31
Q 550 C 670〜 830 550 530 490 16 0 55
D - 20 47
E - 40 31
Q 620 C 710〜 880 620 590 550 15 0 55
D - 20 47
E - 40 31
Q 690 C 770〜 940 690 590 620 14 0 55
D - 20 47
E - 40 31
 
 
Table 8 Mechanical properties of alloy steel pipes
 
Grade Heat treatment a Tensile properties b Brinell hardness
HBW
Quenching (normalizing) Temper Tensile strength MPa Lower yield strength MPa Elongation %
Temperature °C Coolant Temperature °C Coolant
The first time The second time
40Mn2 840 Water, oil 540 Water, oil 885 735 12 217
45Mn2 840 Water, oil 550 Water, oil 885 735 10 217
27SiMn 920 Water 450 Water, oil 980 835 12 217
40MnB 850 oil 500 Water, oil 980 785 10 207
45MnB 840 oil 500 Water, oil 1 030 835 9 217
20Mn2B 880 oil 200 Water, air 980 785 10 187
20Cr 880 800 Water, oil 200 Water, air 835 540
490
10
10
179
179
30Cr 860 oil 500 Water, oil 785
885
685 11 187
35Cr 860 oil 500 Water, oil 930 735 11 207
40Cr 850 oil 520 Water, oil 980 785 9 207
45Cr 840 oil 520 Water, oil 1 030 835 9 217
50Cr 830 oil 520 Water, oil 1 080 930 9 229
38CrSi 900 oil 600 Water, oil 980 835 12 255
20CrMo 880 Water, oil 500 Water, oil 885
845
685
635
11
12
197
197
35CrMo 850 oil 550 Water, oil 980 835 12 229
42CrMo 850 oil 560 Water, oil 1 080 930 12 217
38CrMoAl 940 Water, oil 640 Water, oil 980
930
835
785
12
14
229
229
50CrVA 860 oil 500 Water, oil 1 275 1 130 10 255
20CrMn 850 oil 200 Water, air 930 735 10 187
20CrMnSi 880 oil 480 Water, oil 785 635 12 207
30CrMnSi 880 oil 520 Water, oil 1 080
980
635
835
8
10
229
229
35CrMnSiA 880 870 oil 230 Water, oil 1 620 9 229
20CrMnTi 880 850 oil 200 Water, oil 1 080 835 10 217
30CrMnTi 880 780 oil 200 Water, oil 1 470 9 229
12CrNi2 860 780 Water, oil 200 Water, oil 785 590 12 207
12CrNi3 860 780 oil 200 Water, oil 930 685 11 217
12Cr2Ni4 860   oil 200 Water, oil 1 080 835 10 269
40CrNiMoA 850 oil 600 Water, oil 980 835 12 269
45CrNiMoVA 860 oil 400 oil 1 470 1 325 7 269

 
5 . 4. 2 hardness
Alloy structure steel pipes with annealed or high temperature tempered condition and wall thickness not less than 5 m m shall have a Brinell hardness as specified in Table 8.
5.4.3 Impact
5. 4. 3. 1 Low-alloy high-strength structural steel pipe, when the outer diameter is not less than 70 mm and the wall thickness is not less than 6.5 mm, the longitudinal impact test shall be carried out, and the test temperature of the Charpy V-notch impact test and The energy absorbed by the impact shall comply with the requirements of Table 7. The shock absorption energy is calculated as the arithmetic mean of a set of 3 samples, allowing a single value of one of the samples to be lower than the specified value, but not less than 70% of the specified value.
5. 4. 3. 2 The impact absorption energy in Table 7 is the Charpy V-notch impact absorption energy requirement value of the standard size sample. When the size of the steel pipe cannot prepare a standard size sample, a small size sample can be prepared. When using small-sized impact specimens, the minimum Charpy V-notch impact energy requirements should be the standard-size specimen impact energy requirements multiplied by the decreasing factor in Table 9. The size of the impact specimen should be preferentially selected to a larger size.
 
Table 9 Impact absorption power reduction coefficient of small size samples
 
Specimen specification Sample size (height X width) / mm Decreasing coefficient
Standard size 1 0 X 10 1.00
Small sample 1 0 X 7.5 0.75
Small sample 1 0 X 5 0.50
 
 
5. 4. 3. 3 According to the requirements of the purchaser, the supplier and the buyer shall negotiate and indicate in the contract that the other grades of the steel pipe may also be subjected to the Charpy V-notch impact test. The test temperature, test size and impact absorption energy are The supply and demand sides will negotiate and determine.
 
 
5 . 5 process performance
5 . 5 . 1 flattening
The grades are 10, 15, 20, 25, 20Mn, 25Mn, Q345, Q390, the nominal outer diameter is >22 mm~600mm, and the steel pipe with the wall thickness to outer diameter ratio of not more than 10% shall be crushed and tested. The distance between the plates should meet the requirements of Table 10. After crushing, on the sample
There should be no cracks or cracks.
 
Table 10 Distance between flat steel plates
 
Grade Flattening test flat board spacing Ha/mm
1 0、1 5、20、25 D X 2/3
Q 345. Q 390. 20 Mn . 25 Mn D X 7/8
The minimum plate spacing (H) for the flattening test shall be 5 times the wall thickness of the steel tube.
 
 
5.5.2 Bending
According to the requirements of the purchaser, the supply and demand sides negotiate and indicate in the contract that the steel pipe with an outer diameter of not more than 22mm can be bent. The bending angle is 90°, and the radius of the core is 6 times the outer diameter of the steel pipe. There should be no cracks or cracks in the bend.
5 . 6 surface quality
The inner and outer surfaces of the steel pipe should not have visible cracks, folds, crusting, milk breaks and separation. These defects shall be completely removed and the depth of removal shall not exceed the lower deviation of the nominal wall thickness. The actual wall thickness at the cleaning site shall not be less than the minimum allowed by the wall thickness. Other local imperfections that do not exceed the deviation below the wall thickness are allowed to exist.
5 . 7 Nondestructive testing
According to the requirements of the purchaser, after consultation between the supplier and the buyer, and in the contract, the steel pipe can be non-destructively tested by one or more of the following methods:
A) The ultrasonic testing predetermined GB / T 5777-2008, and comparison sample tube groove depth levels: cold drawing (rolled) pipe for L3, rolled (expanded) steel pipe L4;
b) eddy current inspection according to the provisions of GB/T 7735—201 6 , acceptance level E4H or E4;
c) Magnetic flux leakage test according to GB/T 12606—201 6 and acceptance level F4.
5 . 8 galvanized layer
According to the requirements of the purchaser, the supply and demand sides negotiate and indicate in the contract that the steel pipe can be galvanized for delivery. When the steel pipe is delivered by galvanizing, the relevant requirements for the galvanized layer shall comply with the provisions of Appendix A.
 
 
 

6 Test methods
6.1 The chemical analysis of the steel pipe is sampled according to the rules of GB/T 2006 6 . Chemical composition analysis is usually carried out according to GB/T 4336, GB/T 20123, GB/T 201 24, GB/T 20125 or other common methods. The arbitration shall be in accordance with GB/T 223. 5, GB/T 223. GB/T 223. 11. GB/T 223. 12. GB/T 223. 14. GB/T 223. 19. GB/T 223. 23. GB/T 223. 26. GB/T 223.37, GB/T 223. 40. GB/T 223. 60. GB/T 223. 62. GB/T 223. 63. GB/T 223. 68. GB/T 223.78, GB/T 223. 84 , GB/T 223. 86, GB/T 20125 provisions.
 
6.2 The size and shape of the steel pipe shall be measured with a gage that meets the accuracy requirements.
6.3 The inner and outer surfaces of steel pipes shall be visually inspected under adequate lighting conditions.
6.4 Sampling methods and test methods for other inspection items of steel pipes shall comply with the requirements of Table 11.
 
Table 11 Inspection items of steel pipes, sampling quantity, sampling method, test method
 
Test items Number of samples Sampling method Detection method
Chemical composition Take 1 sample per furnace GB/T 20066  
Stretching test Take 1 sample on each of two steel tubes in each batch GB/T 2975 GB/T 228.1
Hardness test Take 1 sample on each of two steel tubes in each batch GB/T 231.1 GB/T 231.1
Impact test Take one set of 3 samples on each of the two steel pipes in each batch GB/T 2975 GB/T 229
Flattening test Take 1 sample on each of two steel tubes in each batch GB/T 246 GB/T 246
Bending test Take 1 sample on each of two steel tubes in each batch GB/T 244 GB/T 244
Ultrasonic testing Root by root GB/T 5777— 2008
Eddy current testing Root by root GB/T 7735— 2016
Leak detection Root by root GB/T 12606— 2016
Galvanized layer  
 
 
 
7 Inspection rules
7.1 Inspection and acceptance
The inspection and acceptance of steel pipes shall be carried out by the supplier's quality and technical supervision department.
7.2 Batch rule
7.2.2 Steel pipes are inspected and accepted in batches.
7 . 2 . 2 If the steel pipe is not heat treated after it has been cut into individual pieces, all pipe sections taken from a tube blank steel pipe shall be regarded as one.
7 . 2 . 3 Each batch shall consist of steel pipes of the same grade, the same heat number, the same specification and the same heat treatment system (heating). The quantity of each batch of steel pipes shall not exceed the following provisions:
a) The outer diameter is not more than 76 mm, and the wall thickness is not more than 3 mm: 400.
b) The outer diameter is greater than 351 mm: 50 roots.
c) Other sizes: 200 pieces.
d) The number of remaining steel pipes, if not less than 50% of the above-mentioned provisions, is separately listed as a batch, and less than 50% of the above-mentioned provisions can be incorporated into the same grade, the same furnace number and the same specification. In a batch.
7.3 Number of samples
The sampling quantity of each batch of steel pipe inspection shall comply with the provisions of Table 11.
7.4 Re-inspection and decision rules
The re-inspection and determination rules of steel pipes shall comply with the provisions of GB/T 21 02.
 
 
8 Packaging, sign and quality certificate
The packaging, marking and quality certificate of steel pipes shall comply with the provisions of GB/T 2102.






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