What type of steel pipe should be used for low-temperature liquid CO2?
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Dear sea friends, there are low-temperature liquid CO2 pipelines available at temperatures of -15°C, -30°C, and -45°C. I used 304 material in the past, but it seemed too expensive; is it possible to use carbon steel pipes instead? What standards and specifications should be followed? Thank you!
SHT 3059-2012: Specifications for the selection of materials for pipelines in the petrochemical industry. You might want to take a look at it; it specifies the temperature range for each type of material. For temperatures below -20°C, stainless steel is generally used
This post was last edited by Yimi on 2015-7-31 at 17:33. Considering only the temperature factor, my personal opinion (based on the temperature limits specified for the pipes themselves) is as follows: the minimum operating temperature for carbon steel is -20°C. Moreover, according to current pipe standards, the impact test at -20°C must be carried out in accordance with an agreement between the parties, which means additional requirements need to be stipulated. -At 30°C, Q345E can be considered; at -45°C, A333 Gr.6 can be considered. All three of these are much cheaper than 304. The corrosivity of liquid CO2 at low temperatures should be low; however, the presence of other impurities may cause corrosion to carbon steel or low-temperature carbon steel. Special attention should be paid to stress corrosion, which needs to be considered separately.
Stainless steel is already cheap enough these days.
For low-temperature pipelines, only stainless steel, copper pipes, and aluminum pipes can be used; carbon steel pipes are not suitable.
The corrosivity of liquid CO2 at low temperatures should not be significant, so stainless steel is a suitable choice
-15 degrees is suitable for carbon steel; other stainless steels are not suitable
Thank you to all the fellow sailors above for their replies. Some manufacturers use 16Mn – what do everyone think?
What the original poster said makes sense; I’ve learned something, thanks!
304 isn’t too expensive either; safety is no trivial matter!
This material is no longer included in the new standards, namely the material standards; it has been replaced by materials such as Q345D or Q345E. For details, refer to the specific material standards.