Pipeline material selection and valve selection issues
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I came across a small project recently. The materials include 75% phosphoric acid solution, KOH solution, etc. To transport such fluid, the pressure is less than 0.3mpag and normal temperature. What kind of pipe material is suitable? Is stainless steel suitable? Does it need to be lined with PTFE? For small-diameter pipelines, DN50 or DN32, that transport similar solutions, is it better to use gate valves or ball valves? Do valves need to be lined with PTFE? Please give me some advice from Master Haichuan, thank you! ! Also, does the pump also need to be lined with PTFE? Also, what does PTFE lining mean?
Phosphoric acid belongs to: Medium-strong acid, often used as metal surface treatment agent in industry ； KOH is corrosive and toxic, and easily dissipates heat when exposed to water. If the normal temperature of LZ refers to 0~60 degrees, the pressure of 0.3MPA is not too high, and the pipe diameter is not large. It is recommended to consider a ball valve made of UPVC. Economical and applicable!
Polytetrafluoroethylene lining is for metal valve bodies. There is a PTFE coating on the valve cavity and seals. As for pumps, I am sorry that I am not too familiar with them, but the principle should be the same! This is to prevent corrosive media from directly contacting the metal body of the valve or pump.
The material can be two-way steel. This material is both corrosion-resistant and abrasion-resistant. For small-diameter valves, it is recommended to choose ball valves, which have better sealing performance and overall performance. Pumps are also available in bidirectional steel. Teflon lining refers to the lining of polytetrafluoroethylene on the surface of pipeline components that come into contact with fluid. The temperature and resistance of all rubber-lined equipment is limited by the properties of the rubber.
This post was last posted by tuotuo518 on 2010-1-6 19:25 Editor: The diameter of the pipeline is small and it is a corrosive medium. It is best to use a ball valve. If the temperature is not too high, a polypropylene ball valve can be used. The pipeline can also be lined with PTFE or PP. The pump can be reinforced polypropylene or a ceramic pump. The cost is not high. Now a corrosion-resistant pump with a pump body material of PFA has just been released, with a temperature resistance of 200°C.
The temperature and pressure are not high. I personally recommend using a plug valve. The plug valve is entirely lined with PTFE (the valve core and valve body are both lined with PTFE), and WCB is sufficient for the valve body. Because the valve core and valve seat of the plug valve are always in contact, the medium in the valve cannot reach the packing. Even if the valve is connected to the packing, the valve is still sealed by the packing, so it can be guaranteed that there will be absolutely no leakage. For toxic media, double sealing structure must be used. Valve and pump linings are made by lining the cast valve body or pump body with a layer of PTFE material on the inner wall. For places with high corrosion requirements, it is recommended to use DuPont or Daikin materials as PTFE materials. If no lining is used, CD4MCU or 20# alloy can be used.
It is best to use a fluorine-lined ball valve because the diameter is relatively small! As for what fluorine-lining is, the valve body is covered with a layer of rubber to prevent corrosive media from reacting with the metal, thus affecting the service life of the valve! If you still don’t understand it, just look at the actual picture to see it!
Use stainless steel ball valve and pneumatic pump. carbon steel pipeline