Problems encountered during driving regarding the material of the alkali pipeline
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This post was last edited by sunjl1981 on 2013-1-6 at 20:01. The alkali pipelines in our factory are made of stainless steel, rubber-lined steel, and PPH reinforced fiberglass. The alkali pipes running from the alkali sump to the electrolyzer, as well as those running from the electrolyzer to the circulation tank, are all made of PPH-reinforced fiberglass. The system has only been in operation for 5 days; due to the excessive distance between the support points (approximately 6 meters apart), the 250-diameter PPH pipes were bent under the pressure of the alkali solution. There was a weld leak in the alkali pipe leading into the tank; at first, 2 buckets of alkali leaked out every half day, but the leakage accelerated over time. Roughly speaking, 3.6 cubic meters of alkali leaked out per day, which forced us to stop operations today and replace the pipe. Based on the observations I’ve made in my workplace, I can summarize the following points: Stainless steel is used for transporting alkaline solutions at lower temperatures, but it suffers severe corrosion due to high-temperature alkalis. Rubber-lined steel is used for transporting alkaline liquids at high temperatures; it is generally applied to the pipes before and after the pump inlet and outlet, can withstand high pressures, and is resistant to corrosion by hot alkalis. PPH pipes are used for the inlet and outlet overflow pipes of electrolyzers; although they are not corroded by alkalis, their strength is too low to withstand pressure, and their welds are prone to leakage. Due to these two issues in our unit, I am now very skeptical about PPH-reinforced fiberglass pipes. I’d like everyone to discuss the following: 1. Have you encountered similar problems at your respective factories? Are most PPH pipes quite fragile? Is it possible that the pipes purchased by my company have quality issues? What are the advantages and disadvantages of 2PPH pipes? What advantages does it have over rubber and stainless steel in terms of steel? Can the PPH pipes for entering and exiting the electrolyzer be replaced with rubber-lined steel ones? (Nickel pipes need not be mentioned; ignoring economic factors, they are better than any other ones.) ） .Note♀ ） # ♀ ， 。
Using steel-lined PTFE pipes can solve the problem; you can contact me at 13965956360
PPH pipes are used in alkaline pipelines with high temperatures; their high coefficient of expansion can easily cause the joints to crack, which is very unsafe. (It seems that PPH pipes are still performing well abroad; perhaps the manufacturing standards in China are not yet advanced enough.) Pipes with a steel lining covered in PTFE are a good option, and 310S material is preferable if possible. Steel-lined pipes are difficult to install, as it’s hard to make changes once they have been prefabricated, while 310S makes installation easier.)
Fluorinated lining pipes seem nice; they should be very durable and safe
Reply to 3# Xiaoye: Oh, from what you say, it might be a quality issue!
Hehe, it’s best to use 310S; Beihua Machinery and Asahi Kasei both use it. If the manufacturer requires that metals not be used, then the only option is to use a steel lining. Changing the lining to steel is quite troublesome, and it’s necessary to check carefully whether the lining is in good condition; otherwise, any problems that arise later will make it difficult to determine where the issue lies
The selection of pipes around the electrolysis cell is crucial. For high-temperature alkaline pipelines, 310S is the best choice; although the initial investment is high, it offers reliable performance and a long service life ； Alkaline pipelines in low-temperature environments can be made of 304 or 316 materials. PPH is difficult to repair, has low strength, ages easily, and its lifespan is likely to be no more than 6 years. Steel-lined rubber products also suffer from aging issues; even if there is no delamination during use, cracks caused by aging will appear in the rubber after about 8 to 10 years of use. Steel-lined with fluorine is a good option, but its price is also quite high. I suggest you weigh the options.
Our factory’s electrolyzer inlet and outlet pipes are also made of PPH material, which has many disadvantages. One of them is that its expansion capacity is too high, requiring the installation of a large number of expansion joints； Second, the strength is too low, making the weld area extremely prone to breaking. We are planning to gradually replace it with 310S material.
Thank you all for your advice. Although it’s not possible to replace the pipes at the moment, I’ve learned a lot from discussing this with you, and I’ll use this knowledge in the future as well
Everyone might consider using steel-reinforced plastic composite pipes as a substitute for PPH and steel-lined rubber pipes. Of course, the maximum operating temperature for such pipes is 80°C; as long as this limit is not exceeded, they are suitable for use. They are resistant to alkali corrosion, easy to install, have high strength, and a low linear expansion coefficient.
If calculated carefully, the price difference between steel-lined PTFE pipes and SS304 stainless steel pipes is not significant, www.czjfl.com