Consultation on seal materials for pumps in strongly alkaline media
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This post was last edited by 156026692 on 2019-5-17 at 19:07. Our company is a enterprise specialized in the deep processing of liquefied gas. Recently, the company installed 4 new chemical pumps, which handle highly alkaline chemical solutions. The sealings used for these pumps are of the bimetallic type, with models 25 and 45; they are not ordinary external PTFE seals. May I ask what specification this type of mechanical seal has? Is it a standard-specification mechanical seal? In addition, in the medium of one of these two sets of pumps, namely the set with model 45, there was still a certain amount of chloride ions, which resulted in significant corrosion of the impellers made of 304 material, as well as of the impeller nuts, shaft sleeves, and mechanical seals. If everything is to be replaced, what type of spare parts would be the best choice? Below are the pictures of the mechanical seal
What specification is this machine seal?
2507 can also be used; it’s better than 2205!
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If chloride ions are present, it is not recommended to use stainless steel pumps. Use a tetrafluoride pump. The mechanical seal can be replaced with a modular double-faced mechanical seal; an WB2 seal installed externally is also an option. It’s only now that it’s been determined that the friction surface should be made of pressure-sintered silicon carbide
Since it is a strong alkaline chemical, ordinary centrifugal pumps should not be used; instead, magnetic pumps or hydraulic diaphragm pumps are preferable. If possible, shielded pumps can be chosen. For seals, use fluororubber O-rings with silicon carbide (hard) stationary rings and resin-impregnated graphite (soft) moving rings. Sealing springs, push rings, and ring seats made of 316L or 904 stainless steel. The impeller, cover, and pump casing all need to be replaced with 316L material. It might be better to switch to a magnetic pump; it’s just my personal opinion, but I hope it can help you
This is a standard mechanical seal; if the material needs to be changed, you can turn to a professional manufacturer. 15162675113
Given your current conditions, it’s not easy to recommend a specific material directly. As for the resistance of stainless steel to chloride corrosion, it’s necessary to know the operating temperature of the medium; you can find relevant tables by searching on Baidu. Generally speaking, 316L is sufficient
Hello. I have a question: according to mechanical design manuals, silicon carbide is not resistant to strong alkalis, and the stationary ring is made of a soft material while the rotating ring is made of a hard material. Are there any special considerations here?