Material selection for gaseous hydrochloric acid
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For drying solid materials under negative pressure, where the moisture consists of water and a small amount of hydrochloric acid, how should the materials be selected?
Generally, stainless steel is not suitable when chloride ions are present; consider using titanium lining or another type of lining instead
If hydrochloric acid is present, it is recommended to use plastic-lined or CPVC materials; considering negative pressure, liner tubes are not advisable, while CPVC material can be used
It should be related to the material selection for the negative-pressure vacuum pipeline; however, hydrochloric acid is unlikely to be present – it’s more likely hydrogen chloride gas. First, use an I-type pipeline to pump out the exhaust gases and determine the concentration of chloride ions, in terms of PPM. The material choice is also closely related to temperature; if the temperature is below 80 degrees and the chloride ion content is less than 200 ppm, then using 316L is perfectly fine. If those conditions are not met, it is recommended to use 2205 (actually, it can be used at higher temperatures as well, but the main concern is high temperatures). At even higher temperatures, TA2 becomes the only option. TA2 is more expensive, but since a single pipe is not likely to be very thick or long, there should be no problem. Then you can also use ceramic pipelines, or fluorinated carbon steel pipelines (it should be specified that these are for use under negative pressure, as the manufacturing processes for fluorinated pipelines differ for positive and negative pressure applications). If you still think those aren’t suitable, you can use FRPP pipelines. Any of the above will do.
Glass lined with steel, resistant to negative pressure and your process temperatures, and does not deform.
Negative pressure is achieved using PPH pipes, and the temperature can be below 135°C
From economic and safety perspectives, it is recommended to use reinforced polypropylene material
There are no requirements regarding operating temperature and pressure... The suggestions given aren’t very useful; in terms of the information provided on the surface, using FRP or Teflon lining would suffice