TORICH INTERNATIONAL LIMITED |
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GB/T 20409 Multi-Rifled Seamless Steel Tubes for High-Pressure
Boiler
Spec:
Material:20G , 20MnG , 25MnG , 12CrMoG , 15CrMoG
Size Range:OD:4-1200mm
WT:0.3-200mm
General Length:8-12m
Tolerance:
According to the following tables or customers’ request.
Longitudinal mechanical properties of internal screw tubes at room temperature
Number | Grade | tensile strength
MPa(N/ | Lower yield strength![]() ![]() | Elongation A/% | Impact energy
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Not less than | |||||
1 | 20G | 410~550 | 245 | 24 | 35 |
2 | 20MnG | ≥415 | 240 | 22 | 35 |
3 | 25MnG | ≥485 | 275 | 20 | 35 |
4 | 12CrMoG | 410~560 | 205 | 21 | 35 |
5 | 15CrMoG | 440~640 | 235 | 21 | 35 |
The grade and chemical composition of steel
Number | Brand | chemical composition(mass fraction)/ % | ||||||
C | Mn | Si | Cr | Mo | S | P | ||
1 | 20G | 0.17~0.23 | 0.35~0.65 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
2 | 20MnG | 0.17~0.23 | 0.70~1.00 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
3 | 25MnG | 0.22~0.29 | 0.7~1.00 | 0.17~0.37 | -- | -- | ≤0.020 | ≤0.025 |
4 | 12CrMoG | 0.08~0.15 | 0.40~0.70 | 0.17~0.37 | 0.40~0.70 | 0.40~0.55 | ≤0.020 | ≤0.025 |
5 | 15CrMoG | 0.12~0.18 | 0.40~0.70 | 0.17~0.37 | 0.80~1.10 | 0.40~0.55 | ≤0.020 | ≤0.025 |
Note1:Residual element content of 20G,20MnG,25MnG should satisfy: Cu≤0.20%,Cr≤0.25%,Ni≤0.25%,V≤0.08%,Mo≤0.15%;The remaining elements of other brands should satisfy: Cu≤0.20%,Ni≤0.30%. Note2:The acid soluble aluminum in 20G steel should not be more than 0.010%. Note3:The nitrogen content of the steel produced by the oxygen converter plus the refining of the furnace should not be more than 0.008%. |
Characteristic:
TORICH QUALITY ASSURANCE
Good surface quality
Good OD and ID tolerance controlled to Technical Standard
Stable quality
100% Eddy Current Test
Processing:Cold drawning
Technical Delivery Conditions:Heat treatment
Widely used in the field of:High-pressure boiler