I would like to ask why 20# steel is generally used for pipes?
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I would like to ask why 20# steel is generally used for pipes? Why not use carbon steel such as Q235B or other materials?
@Yimi @dlutyj, please help and explain it.
I remember asking my master this question back then, and he explained that in many cases, Q235 can also meet the requirements regarding temperature and pressure. However, the processing standards in China might be slightly inferior, so as a precaution, petrochemical projects generally do not use pipes made of Q235. In terms of performance, steel grade 20 is a high-quality carbon structural steel, while Q235 is also a carbon structural steel. Overall, steel grade 20 is more suitable.
Thank you so much for your patient answers! ! ! ! ! Now I understand!
I see, haha. I’ve just started working in this field as well and don’t know anything yet, so I wanted to ask and learn a bit more
Q235 is ordinary carbon steel, while 20 steel is high-quality carbon steel. Of course, when companies have sufficient financial resources, they prefer to choose materials that offer both good quality and reasonable prices. Q235 is suitable for use as general-purpose materials, but it is likely too risky for use in chemical pipelines
I see! ! For our ordinary mechanical equipment, such as pumps and various heat exchangers, when we say that the material used is carbon steel, is there a specific value for the carbon content in this ordinary carbon steel? Or will different types of carbon steel still be used in such cases?
Materials such as Q235 and Q245 have specific carbon content values. By ordinary materials, I mean those whose carbon content does not affect safety; things like guardrails and iron drums fall into this category. Pumps, on the other hand, are probably not made from materials like Q235
It depends on what kind of device it is and what fluid is flowing in the pipeline.
Ordinary pipelines do not require such high strength; Q235B is a steel material with a yield strength of 235 MPa, and it is sufficient for ordinary pipelines to meet the required standards
Q235B is a steel plate grade, while 20 steel is a steel pipe grade. For steel plates to become steel pipes, they need to be rolled and welded; therefore, steel pipes made of Q235B material refer to welded steel pipes ； 20 steel is a seamless steel pipe.