Revisiting the material issues related to hydrogen peroxide pipelines
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There was a post earlier discussing the material issues related to hydrogen peroxide pipelines. See https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=2182602&highlight=%CB%AB%D1%F5%CB%AE%B9%DC%B5%C0. Coincidentally, I currently have a 27.5% hydrogen peroxide pipeline and equipment available. Party A asked which medium to use. I checked the \"Corrosion Data and Material Selection Manual\" – both 304 and 316L can be used, but there is one requirement: PH > 7. Does this need alkali solution to be added to maintain it? If 304 and 316L are chosen, does that mean the hydrogen peroxide purchased by the client needs to have a pH value of >7?
For 27.5% hydrogen peroxide, it is feasible to use 304 or 316L stainless steel as the pipe material, but attention must indeed be paid to the pH level. This is because under acidic conditions (pH < 7), hydrogen peroxide causes severe corrosion to stainless steel. It is generally recommended that the pH of hydrogen peroxide be maintained at neutral or slightly alkaline to reduce the risk of corrosion. If the pH value of the existing hydrogen peroxide is less than 7, it can indeed be adjusted to a pH greater than 7 by adding an appropriate amount of alkali (such as sodium hydroxide). This requires adjustment based on the actual conditions, while monitoring the pH value to ensure it remains within a safe range. Therefore, you can suggest that the client request hydrogen peroxide with a pH value greater than 7 at the time of procurement, or take the necessary adjustment measures to ensure the long-term stable and safe operation of the piping system. It is also necessary to consider regularly monitoring the pH value of hydrogen peroxide to ensure it remains at an optimal level. .
T/CUWA-10104-2023 - Technical Specifications for Ozone Water Treatment Engineering: 3.7.2 The materials shall meet the following requirements: 1. Equipment, valves, pipes, etc. that come into contact with ozone or gases and liquids containing ozone shall be made of 022Cr17Ni12Mo2 stainless steel or other materials resistant to ozone corrosion； The sealing material should be an ozone-resistant material such as polytetrafluoroethylene ； 4 When the chloride ion concentration in the raw water fed into the ozone contact tank is higher than 800 mg/L, corrosion-resistant materials such as 022Cr23Ni5Mo3N stainless steel (UNS S31803) should be used for the materials in contact with ozone and the raw water.
In accordance with the requirements of the \"T/CUWA-10104-2023 - Technical Specifications for Ozone Water Treatment Projects\", for equipment, valves, pipes, etc. in ozone water treatment projects that come into contact with ozone and ozone-containing gases or liquids, it is recommended to use 022Cr17Ni12Mo2 (equivalent to 304L or 316L stainless steel) or materials with higher resistance to ozone corrosion. Furthermore, the sealing material should be an ozone-resistant material such as polytetrafluoroethylene. When it comes to raw water intake, if the chloride ion concentration is above 800 mg/L, it is recommended to use the more corrosion-resistant 022Cr23Ni5Mo3N stainless steel (UNS S31803, commonly known as duplex stainless steel 2205). This material has a greater tolerance to chloride ions and can better withstand highly corrosive environments. In summary, when designing and selecting materials, appropriate materials should be carefully chosen based on the ozone concentration and the properties of the medium in contact, to ensure the long-term stability and safe operation of the system. .
Hydrogen peroxide pipelines can use 304L or 316L. The pipeline is ready once it has been pickled and passivated.
The normal pH of hydrogen peroxide should be around 3. Stable in acidic conditions; for normal use, 304 steel or fiberglass is used.