Corrosivity of propylene oxide

It is best to use stainless steel storage tanks; PO can resist the corrosion caused by propylene oxide

If your company has the financial means to use titanium

You need to take into account the requirements of the products you produce, especially if it is necessary to control metal ions! Then stainless steel 304 will do. Previously, carbon steel tanks could be used, but it seems that the new chemical industry standards require stainless steel tanks now.

Thank you all, but using titanium for the PO is a bit of a waste, haha. I’ll check the specifications.

The whole 304 version isn’t too expensive

I. Corrosion Analysis 　　(1) Chloropropene reaction and quenching system: If propylene contains water, hydrochloric acid is generated, which corrodes the equipment following the mixer. The quenching tower, reboiling separation tower, bottom reboiler, and top condenser are all made of carbon steel, and they are subject to uniform corrosion caused by hydrochloric acid. The reactor material is 316L, which is susceptible to uniform corrosion by hydrochloric acid and chloride-induced stress corrosion cracking. 　　(II) Reaction product discharge cooling and dechloropropane system: The reaction gas coming from the tower top condenser contains chlorides; if the feedstock is moist or improper operation leads to an excessive amount of water, it will cause uniform corrosion of carbon steel equipment. There is corrosion in the feed tank of the depropanization tower and below the middle section of the depropanization tower. 　　(III) Chloropropane distillation system: Water-containing organic chlorides enter this chloropropane distillation system, causing uniform corrosion of hydrochloric acid on the low-boiling-point tower, condenser, and top tank of the carbon steel equipment. 　　(IV) Propylene washing and compression system: The gaseous propylene coming from the top of the hydrochloric acid absorption tower contains hydrochloric acid, which reacts with alkali in the alkaline washing tower. The propylene at the top of the tower enters the refrigeration compression process, where residual hydrochloric acid is neutralized with alkali in the inter-stage scrubber tower and the make-up alkali scrubber tower to produce clean high-pressure propylene. There is slight hydrochloric acid corrosion in this system; through the following process, the pH changes from acidic to alkaline, which reduces the problem of uneven corrosion on the equipment. However, the issue of alkali embrittlement cracking still needs to be considered; it can occur when the concentration exceeds 5% and the temperature exceeds 50°C. This situation tends to arise during steam purging when the system is shut down or when steam is used for heating alkali pipelines. 　　(5) Propylene drying and condensation system: The high-pressure propane supplied from the alkali scrubber at T107 contains a small amount of moisture. If the pH level in this system is not properly controlled, there may be a small amount of hydrochloric acid, which can cause corrosion to the carbon steel equipment in this system, such as the propylene collection tanks, propylene separation tanks, and accumulation tanks. 　　(VI) Dichloropropane reaction system: In this system, chlorine reacts with water to form hydrochloric acid; the dichloropropanol produced as a result of this reaction, together with water and hydrochloric acid, causes corrosion of downstream equipment due to the hydrochloric acid. Such as: dichloropropanol storage tanks, pipelines, etc. 　　(7) Dechlorohydrin system: Dichloropropanol, which contains water and hydrochloric acid, reacts under alkaline conditions, simultaneously neutralizing the hydrochloric acid. Carbon steel equipment corroded by hydrochloric acid includes: dichloropropanol heat exchangers, mixers, and the top section of the stripping tower. E204 uses titanium equipment, which is prone to crevice corrosion and galvanic corrosion. 　　(8) Propylene oxide purification system: The propylene oxide coming from the upstream system contains water; this system uses 304L and 316L materials, and it is necessary to take into account the risk of stress corrosion cracking caused by chloride ions. For titanium equipment, issues such as crevice corrosion and galvanic corrosion may arise. For Monel 400 alloy equipment, the presence of oxygen in the medium accelerates material corrosion. 　　(IX) Other corrosion: Corrosion under the insulation layer ； Circulating water corrosion ； Atmospheric corrosion ； Soil corrosion of buried pipelines. 　　II. Anti-corrosion recommendations The protection measures mainly include three aspects: improvements to the manufacturing process, enhancement of the corrosion resistance of equipment, and improvement as well as addition of corrosion detection methods. For corrosion under mild conditions, process-based anti-corrosion measures are the primary approach, with the use of corrosion-resistant materials serving as a supplementary measure ； For corrosion in high-temperature environments or those with large temperature differences, it is advisable to use corrosion-resistant materials. Ensure that all equipment can undergo maintenance every two, three, or four years. 　　(1) Strengthening process anti-corrosion At present, the corrosion in epichlorohydrin plants is mainly caused by hydrochloric acid. To eliminate this potential hazard, process anti-corrosion measures should be the primary approach, supplemented by the use of corrosion-resistant materials; efforts should be made to reduce the levels of HCl, water, and other substances in the process media, in order to mitigate or avoid corrosion caused by hydrochloric acid. 　　The propylene drying unit was improved by adding a desiccant before chlorine enters the mixer, and strict control was exercised over the water content in the feed stream to keep it within acceptable limits – that is, the water content in propylene should be less than 1 ppm, while the water content in chlorine should be less than 10 ppm. 　　Install a device other than HCl after T-101. 　　An operation unit can be added between TK-201 and E-203 to remove acid and water, or one of them. To reduce perforation corrosion on E-203. 　　(II) Improving the quality of equipment: Equipment management, maintenance, testing, and diagnosis. China Equipment Management Network: http://www.sbgl.netwCU. 1. The proper selection of materials for equipment is crucial for corrosion prevention; using appropriate material selection as a key strategy in this regard, establishing one’s own standards for material selection, and keeping abreast of the latest international developments and new materials are all important steps to enhance corrosion resistance and ensure long-term safe operation. 　　2. Improve the structure of the equipment; by analyzing the corroded areas and the mechanisms of corrosion, it can be seen that hydrochloric acid accumulates in the gaps, resulting in high concentrations of this acid and thus pitting corrosion. Most heat exchange occurs at the interface between the baffle and the tube bundle; by using a plate heat exchanger, the presence of dead zones can be reduced. 　　3. Applications of surface modification techniques, such as surface diffusion infiltration and chemical conversion ； The use of corrosion-resistant materials, such as phenolic resins, epoxy resins, glass, ceramics, etc

Stainless steel storage tank (304) – that’s sufficient

In the propylene oxide production process, there are highly corrosive substances such as HCl and Cl2, so stainless steel is required for the equipment. According to the standards for industrial propylene oxide, galvanized iron drums are sufficient as transport packaging. According to the available information, carbon steel storage tanks are used for daily storage. I have never seen storage tanks made of stainless steel; could an expert please indicate the source?

What would be the cost to construct a TA storage tank with a capacity of thousands of m³? The 1400m³ PO storage tank designed by a certain design institute uses Q235-A material and has its inner wall treated with hot-dip zinc plating for corrosion protection; it is equipped with an internal floating roof and stainless steel chilled water coils to control the storage temperature and prevent evaporation. For reference only

The pipes that were newly installed in our factory are also carbon steel! What are the new chemical industry standards?