Material selection for low-temperature methanol washing piping
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How should pipe materials be selected for piping in the low-temperature methanol washing unit? Are there any references available? The materials commonly used for low-pressure pipelines are 304, 16Mn, and 20#. Generally, 304 is used at low temperatures, while 16Mn and 20# are more suitable for high temperatures. So how should one choose between 16Mn and 20#, and why?
The most important one is low-temperature steel; this material is determined by the materials engineering department, I guess – your company probably handles both materials and piping work! There are many factors to consider when selecting materials: in terms of design temperature, stainless steel is used for pipelines below -45 degrees; low-temperature carbon steel is used at around -45 to -10 degrees, while 16Mn and carbon steel are used for higher temperatures ； It is also necessary to consider the composition of the medium; for example, whether there is corrosion, and in that case stainless steel is a better choice ； H2S corrosion, H-corrosion, and so on. The materials science field requires a high level of expertise when it comes to material selection; I’m an outsider in this area, so these are just my preliminary opinions!
Cold areas use low-temperature stainless steels such as 304 and 316; hot areas use 16Mn and carbon steel
So, how should one choose between carbon steel and 16MN? What are the differences?
What is the difference between carbon steel and 16MN? How to select materials
16MN is generally a steel used for pressure vessels, intended for manufacturing equipment； Carbon steel, on the other hand, is more widely used – for pipes, fittings, etc. It can also be used in pressure vessels where lower requirements are imposed
For temperatures below -20 degrees, use 16MN steel; for higher temperatures, use grade 20 steel