Standards：
GB／T8163 Chinese national standard
Application： 
General seamless steel tubes for conveying fluids
Model No.of major steel tubes：
10,20,Q345,etc．
Diamensional tolerances:
|
Types of steel tubes
|
Outer diameter
|
Wall thickness
|
|
Cold-rolled tubes
|
Tube sizes(mm)
|
Tolerances(mm)
|
Tube sizes (mm)
|
Tolerances(mm)
|
|
＞30～50
|
±0.3
|
≤30
|
±10％
|
|
＞50～219
|
±0.8％
|
|
Hot-rolled tubes
|
＞219
|
±1.0％
|
＞20
|
±10％
|
Mechanical properties：
|
Standard codes
|
Models of steel tubes
|
Tensite strength（MPa）
|
Yield strength（MPa）
|
Elongation（％）
|
|
GB/T8163
|
10
|
335～475
|
≥205
|
≥24
|
|
20
|
410～550
|
≥245
|
≥20
|
|
Q345
|
490～665
|
≥325
|
≥21
|
Chemical composition:
|
Standard codes
|
Models of steel tubes
|
Chemical compositions（％）
|
|
C
|
Si
|
Mn
|
P
|
S
|
Cr
|
Ni
|
Cu
|
|
GB/T8163
|
10
|
0.07～0.14
|
0.17～0.37
|
0.35～0.65
|
≤0.035
|
≤0.035
|
≤0.15
|
≤0.25
|
≤0.25
|
|
20
|
0.17～0.24
|
0.17～0.37
|
0.35～0.65
|
≤0.035
|
≤0.035
|
≤0.25
|
≤0.25
|
≤0.25
|
|
Q345
|
0.12～0.20
|
0.20～0.55
|
1.20～1.60
|
≤0.045
|
≤0.045
|
/
|
/
|
/
|
