Material selection for steam pipes
Thread Content
Question: For steam at 3.5 MPa and a temperature of over 400°C, what material should be used for the pipes?
For steam pipes, carbon steel pipes will suffice.
I would like to ask the person above: can carbon steel meet the above operating conditions?
The material of steam pipes is related to temperature: Material, Recommended operating temperature, Maximum allowable temperature. Steel No. 10: -20～425, 430; Steel No. 20: -20～425, 430; 20G: -20～430, 450; 16MnG: -10～400, 400; 15CrMo: 510, 550; 12CrMoV: 540~555, 570; 12Cr1MoV: 540~555, 570; 12CrMoWVTiB: 540~555, 600; 12Cr3MoVSiTiB: 540~555, 600. For temperatures between 400℃ and 450℃, 20G/15CrMo is recommended.
Using carbon steel at temperatures above 400 degrees is quite risky; I think low-alloy steel could be used instead
In terms of material selection, using carbon steel is indeed not a problem. However, the allowable stress of carbon steel also decreases rapidly at 400°C; therefore, a larger wall thickness is required when using carbon steel. Alloy steel is recommended.
Above 400°C, but by how much?
There must be an upper limit on the operating temperature. Although carbon steel can be used, it is only just sufficient. We choose 12CrMoG-GB5310
TEMP F -20 to 100 200 300 400 500 600 700 800 TEMP C -29 to 38 93 149 204 260 316 371 427 For NPS ½ through NPS 24 (Full flange ratings per ASME B16.5, Table 2-1.1.) psig 740 675 655 635 600 550 535 410 kPag 5100 4655 4515 4380 4135 3790 3690 2825 CS, SMLS, ASTM A106-B
The pressure is too high; the above-mentioned carbon steel A106-B can be used, but only barely
At 230 degrees Celsius and 1.0 MPa, 20# steel is used – that’s the standard specified by our company! As for the conditions listed by LZ, I’m not sure whether carbon steel would be suitable