Seek advice on pipe selection
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Can carbon steel pipes be used for liquid ammonia at -40°C?
I’m a bit worried about the brittleness of the pipes at low temperatures; I’m not sure if this is correct. I would appreciate some guidance from experts
If the carbon steel pipe you are referring to is 20#, it certainly won’t work; 20# can only be used at temperatures down to -19°C. If -40°C is the design temperature, it is best to use 16Mn or 16MnDG, or A333 Gr.6. If -40°C is merely the operating temperature, it depends on what the design temperature is. 16Mn can only be used at -40°C, while 16MnDG and A333 Gr.6 can be used at -45°C. When the design temperature is below -45°C, it is best to use stainless steel.
For safety reasons, I personally recommend using stainless steel
Carbon steel pipes won’t work; 16Mn is an alloy steel.
Carbon steel won’t work; it cannot withstand deep cold conditions, as -40°C falls within the range of deep cold temperatures. Stainless steel, 16Mn, or nickel-based alloys can be used instead
Use 16Mn; this is the material used for liquid ammonia tanks due to its resistance to low temperatures