I would like to ask if anyone has any good methods for sealing leaks of HCl and acetylene mixtures in the VCM conversion pipeline
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At our company’s conversion unit, the pipes carrying HCL gas and the converters often develop leaks. We usually have to shut down the operation to carry out weld repairs or replace the pipes. Sometimes we try using sealant tapes or magic rods, as well as PTFE packing, but none of these methods prove effective; this results in significant impacts on PVC production. I was wondering if anyone has any suitable methods for fixing such leaks? For example, what organic materials are used to seal the leaks with adhesive? Or what type of pipe material can effectively prevent HCL corrosion? Or through measures such as how to control the manufacturing process? Please feel free to share your suggestions; thank you!
Pressure-based leak repair technology is now quite mature as well; you just need to find a professional company to help you with it.
It is relatively difficult to seal leaks with hydrogen chloride gas under pressure. Regarding the scoring for this type of repair: if it’s just a small leak, one can first use a sealant rod to plug it, then apply metal repair compound, and cover it with 528 and 568 to easily resolve the issue ； In the case of large leaks, if the pressure and temperature are not high, simply wrap the inner tube several extra times; once the leak is stopped, cover it with epoxy glass cloth. Additionally, in the conversion process, water removal devices generally use UPVC/FRP pipes, while the inlet and outlet pipes of the converter are usually carbon steel pipes. If funding permits, considering the use of steel-lined PTFE in the water removal device is an option; it is said that many newly built PVC devices use this approach, and the results are good.
Use a PTFE gasket; otherwise, the best solution is to replace the pipe. Use carbon with a PVC gasket
To solve a problem, it is necessary to analyze its causes. Corrosion of equipment and pipelines indicates that the gas contains high levels of moisture; this should be the focus of attention. Plugging the issues isn’t a sustainable solution!
This method is practical, but to address the root cause, it is necessary to start by reducing the moisture content in the feed gas.
When sealing leaks, it’s also important to prevent them from occurring. In vinyl chloride systems, it is essential to enforce strict control over process parameters and ensure proper operation during production. This includes: 1) the removal of water from acetylene gas. Acetylene is usually transported in a wet form, and effective dehydration of this gas is necessary before it reaches the mixed gas preheater. Low-temperature dehydration at +5 degrees Celsius is typically used, and temperature control via coolers as well as regular drainage management are required. 2. Water removal from the gases used in greening processes: Water content in hydrogen chloride gas implies the presence of a high concentration of hydrochloric acid; therefore, great attention must be paid to the management of water removal from hydrogen chloride gas. Deep refrigeration dehydration or concentrated sulfuric acid dehydration is usually employed, and it is necessary to strengthen index control and effect evaluation. 3. Operate strictly in accordance with the process design to prevent unauthorized flow of hydrogen chloride gas. In some enterprises, due to problems with production process control, hydrogen chloride gas is mistakenly directed toward the acetylene system, causing corrosion and damage to the equipment and pipelines in that system ； After all, the acetylene system is mainly made of carbon steel, which is not resistant to hydrogen chloride corrosion.
Reply 5# bbs.hcbbs.net to agree with the above views
Thank you to all the experts for their advice. The suggestions provided by everyone are truly very practical. If there is anything else, please feel free to add it. I hope we can exchange more and better technical knowledge; thank you all!
Reply to 1# -1 degree: I agree with what was said on floor 5; how much can you block anyway? ! Steel-lined PE is also not good: the pipe diameter decreases, the pipe becomes heavier, and leaks are particularly likely to occur at the flange welding areas! Steel-lined PE pipes are used to produce hydrogen chloride from hydrochloric acid; they often leak, and the pipes have to be ordered from other suppliers...
Personally, I believe that the issue of corrosion caused by water should be addressed by focusing on process parameters, primarily by controlling the temperature at various points and ensuring effective water removal. If the amount of corrosion-related leakage is small, sealing the leak may suffice; however, if the area of corrosion is large, the pipe must be replaced.