Questions regarding acetic acid corrosion

This post was last edited by Litaotao1314 on 2011-11-16 at 09:53. Using PTFE coating or PTFE-lined plates both yields excellent results, with a service life of around 20 years

Hastelloy B-2 alloy: I. Corrosion resistance. Hastelloy B-2 is a Ni-Mo alloy with extremely low levels of carbon and silicon; these low contents reduce the precipitation of carbides and other phases in the welds and heat-affected zones, thereby ensuring good corrosion resistance even in welded conditions. As is well known, Hastelloy B-2 exhibits excellent corrosion resistance in various reducing media, and can withstand the corrosion of hydrochloric acid at any temperature and concentration under normal pressure. It exhibits excellent corrosion resistance in non-oxidizing sulfuric acid at moderate concentrations without inflation, phosphoric acids of various concentrations, high-temperature acetic acid, organic acids such as formic acid, bromic acid, and hydrogen chloride gas; moreover, it is also resistant to corrosion by halogen catalysts. Therefore, Hastelloy B-2 alloy is commonly used in various demanding petroleum and chemical processes, such as the distillation and concentration of hydrochloric acid ； In production processes such as the alkylation of ethylbenzene and low-pressure carbonylation to produce acetic acid.

This post was last edited by hbwxuan on 2011-11-14 at 17:01. I wonder what the maximum temperature can reach with your setup, which is around 100 degrees? It is true that 316L has good corrosion resistance to high-temperature acetic acid, so it is suitable for use in storage tanks or heat exchangers and the like. But since your device is a reactor, for a critical piece of equipment, the issue of safety factor in use also needs to be taken into account – namely, how many years it can operate without problems. It is unlikely that the material can provide such a guarantee (imported materials would be better; this has nothing to do with being overly fond of foreign things). As mentioned above, it’s not practical to use Hastelloy for the entire structure; instead, it is recommended to install a Hastelloy lining in the areas of the reactor where the temperature is high, and that will solve the problem. Additionally, regarding the material issue at atmospheric pressure you mentioned. Given your conditions, the material choice has little to do with pressure; what’s important is the maximum operating temperature of the acetic acid, as well as its concentration.

Reply to 4# hbwxuan: Glacial acetic acid can reach temperatures higher than the boiling point of acetic acid, up to 190°C. .

Reply to 3# wxalloy: Is Hastelloy expensive? What price range is it around?

If it is glacial acetic acid, there will be no problem at this temperature, but the condition is that since it is a reactor, the reaction medium must not contain water. Test data show that 316L exhibits excellent corrosion resistance in glacial acetic acid at temperatures below 204 degrees.

The material contains acetic acid; the temperature is as high as 190°C and the pressure is 1.0 MPa. There are likely other components in this material as well. Could the original poster provide more detailed information? Under these operating conditions, 316L is not corrosion-resistant and will suffer from severe pitting corrosion. As mentioned on the 3rd floor, Hastelloy B or Hastelloy C exhibits excellent corrosion resistance to high-temperature acetic acid; it is possible to consider using carbon steel as the base structure with Hastelloy B/C sheets as linings. The thickness of these linings is determined by the intended service life, and it is generally between 3 and 6 mm. Additionally, safety requirements for standard reaction vessels are quite high; a structure with a titanium lining and a carbon steel core, offering higher reliability, can be considered, with 3mm thick TA2 lining plates being sufficient in most cases. Although Hastelloy and titanium plates are expensive, the manufacturing cost of using a liner structure is not high.

Reply to 7# hbwxuan: I’m hungry. However, the corrosion resistance of stainless steel in acetic acid depends on the surface passivation film. Acetic acid is a weak electrolyte, so the possibility of hydrogen evolution corrosion is low. Theoretically, in the presence of a small amount of water or oxygen, the surface passivation film should form more easily, resulting in better corrosion resistance. .

Using Hastelloy thin plates as a lining is a viable option. 1. Corrosion resistance of Hastelloy C-276: The C276 alloy is suitable for use in various chemical processing industries involving oxidizing and reducing media. The higher contents of molybdenum and chromium enable the alloy to resist corrosion by chloride ions, while tungsten further enhances its corrosion resistance. C276 is one of the few materials capable of withstanding corrosion by humid chlorine, hypochlorite, and chlorine dioxide solutions; this alloy exhibits significant corrosion resistance to high-concentration chloride solutions (such as ferric chloride and copper chloride). 2. Corrosion resistance of Hastelloy B: The nickel-molybdenum alloy Hastelloy B has extremely low levels of carbon and silicon, which reduces the precipitation of carbon and other impurity phases in the weld heat-affected zone; as a result, its welds also possess sufficient corrosion resistance. Alloy Hastelloy B-2 exhibits excellent corrosion resistance in reducing media, such as hydrochloric acid solutions at various temperatures and concentrations. It also exhibits excellent corrosion resistance in sulfuric acid solutions of moderate concentration (or those containing a certain amount of chloride ions). It can also be used in acetic and phosphoric acid environments. Alloy materials can achieve the best corrosion resistance only when they are in an appropriate microstructural state and have a pure crystal structure. Applications of Hastelloy B: Alloy Hastelloy B is widely used in the fields of chemistry, petrochemicals, energy production, and pollution control, especially in industries such as those involving sulfuric acid, hydrochloric acid, phosphoric acid, and acetic acid. For thin plates, Hastelloy C-276: the domestic version costs around 340 yuan, while the imported version costs around 390 yuan

At a temperature of 100°C, with pure liquid acetic acid, 316 is definitely suitable; 316L can be used at up to 170°C in the presence of liquid acetic acid. If CL or Br plasma is present, it won’t work; it is recommended to use S22253 duplex steel or 6MO steel. There’s no need to choose Hastelloy