How long can PTFE-lined pipelines be used for storing and transporting 20%–30% hydrochloric acid?
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Our company produces antioxidants, and the hydrogen chloride gas generated as a by-product increases in concentration after being absorbed by water; the highest concentration can reach 30, while it is usually around 22. Initially, the enamel-coated pipelines were made by the installation team themselves using carbon steel pipes, which were then taken to a factory specialized in enamel coating. Within less than a year of installation, all of those enamel-coated pipelines corroded. Later, PE pipelines were used instead, but xylene is present during the reaction process, which causes the PE pipelines to swell, leading to leaks recently. As for the pump used for absorbing hydrochloric acid, a pump made of tetrafluoride alloy is employed, yet its moving parts often get damaged, which is a real problem. Does anyone among you have any good suggestions or experience with similar installations that could be shared?
Reply to 1# cjhti: May I ask what the level of xylene in your pipelines is approximately? Have the PE pipelines become swollen as a result? Consider using steel-reinforced plastic composite pipes; although the base material is also PE, the pressure resistance does not rely on PE but rather on the steel framework. Therefore, there should be no problems – please refer to this information.
Using PTFE-lined pipes should be fine, but it is essential to ensure that there are no leaks at the pipe flange connections; otherwise, corrosion will occur from the outside inward. If a pump is to be used, it seems that a magnetic pump lined with PTFE or a self-priming pump made entirely of PVDF should work just fine. But be careful not to let it run idle.
This post was last edited by Litaotao1314 on 2011-5-11 at 16:02. There are various options available for the lining material of pipelines made of steel with a fluoroplastic lining
The corrosion resistance of the PTFE lining is not an issue; its service life mainly depends on the PTFE lining manufacturing process, as well as whether corrosion occurs at the joints during installation and use, and whether abrasion leads to punctures in weak areas of the lining. . .
Why not consider using CPVC or PP-H materials? There are many examples of their use in such applications, with excellent results; moreover, they do not suffer from leakage issues like fluorinated lining pipes.
A device of good quality should last more than 5 years without any problems. Our unit once had a high-purity hydrochloric acid production system using an iron furnace process; the concentration of the acid produced was 31%, and yet some of the steel pipes used in that system were completely corroded by the end, yet it continued to be in use. PTFE-lined pipes made of pine are sensitive to negative pressure operations, as the lining tends to collapse.
This post was last edited by Litaotao1314 on 2011-5-11 at 16:02. Fiberglass pipes can solve this issue
This post was last edited by Litaotao1314 on 2011-5-11 at 16:00. Using steel-lined PTFE pipes will do; they are resistant to high temperatures and corrosion, and have a long service life. There’s a chance to discuss it
Many, very good. If the OP has any questions, they can get in touch with me for technical discussions
There’s no issue with fiberglass; it has moderate strength. If the strength is not sufficient, fluorine-coated materials can be used, and corrosion resistance will definitely be no problem – it just depends on the cost