Problems with using carbon steel pipes in refrigeration systems
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According to the design specifications for cold storage facilities, the pipes used in ammonia refrigeration systems can only be made of 10# or 20# carbon steel. However, clause 8.1.3.3-b) of the new standard GB20801.2-2020 stipulates that GC2-grade pipes suitable for low-temperature and low-stress conditions must have a minimum operating temperature of not lower than -104°C, and the carbon steel materials allowed for use do not include carbon structural steel or bolt materials. According to these regulations, can steel pipes of grade 10# and 20# no longer be used for refrigeration pipelines in the future?
I just attended the training session on the new GB20801 standard. The instructor explained that steel grades 10# and 20# are not considered carbon steel; therefore, the use of seamless 10# and 20# steel pipes for refrigeration pipelines still meets the requirements of low-temperature and low-stress conditions, with no changes compared to the old standard.
10# and 20# steel are not considered carbon steel; then what are they?
To be precise, 10# and 20# are merely considered \"carbon steel\", but not \"carbon structural steel\".