Seamless steel tubes for petroleum cracking
Standard:
GB9948 Chinese national standard
Application:
Served as for furnace tubes,heat exchange tubes and pipelines in petroleum and refinery plants
Model No.of major steel tubes:
1n 9n 1ErrMn 1rhMn 1f:hM0 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 |
Tensile(MPa) |
Yield(MPa) |
Elongation(%) |
Impact(J) |
hardness(HB) |
GB9948 |
10 |
330~490 |
≥205 |
≥24 |
/ |
/ |
20 |
410~550 |
≥245 |
≥21 |
≥39 |
/ |
15CrMo |
440~640 |
≥235 |
≥21 |
≥47 |
≤170 |
1Cr2Mo |
≥390 |
≥175 |
≥22 |
≥92 |
≤179 |
1Cr5Mo |
≥390 |
≥195 |
≥22 |
≥92 |
≤187 |
Chemical composition:
Standard codes |
Models of steel tubes |
Chemical compositions(%) |
C |
Si |
Mn |
P |
S |
Cr |
Mo |
Ni |
GB9948 |
10 |
0.07~0.14 |
0.17~0.37 |
0.35~0.65 |
≤0.035 |
≤0.035 |
≤0.15 |
/ |
≤0.25 |
20 |
0.17~0.24 |
0.17~0.37 |
0.35~0.65 |
≤0.035 |
≤0.035 |
≤0.25 |
/ |
≤0.25 |
15CrMo |
0.12~0.18 |
0.17~0.37 |
0.40~0.70 |
≤0.035 |
≤0.035 |
0.80~1.10 |
0.40~0.55 |
≤0.30 |
1Cr2Mo |
≤0.15 |
0.50~1.00 |
0.30~0.60 |
≤0.035 |
≤0.030 |
2.15~2.85 |
0.45~0.65 |
/ |
1Cr5Mo |
≤0.15 |
≤0.50 |
≤0.60 |
≤0.035 |
≤0.030 |
4.00~6.00 |
0.45~0.60 |
≤0.60 |