What special gaskets are used in the production of acetic acid?

There are many types of gaskets for acetic acid applications (the following is based on my personal work experience; as I am not a personnel specialist in equipment, I am an amateur, so the information provided here is for reference only): Special material gaskets: Zirconium-based materials – Generally, the inner layer of special material gaskets is made of Zr702, and they are used in highly corrosive high-pressure pipelines, matching those made of zirconium material. The outer ring is made of stainless steel, typically using 316L material. The central sealing ring is also made of Zr702 material; polytetrafluoroethylene is commonly used as well. Polytetrafluoroethylene possesses excellent corrosion resistance, being virtually immune to corrosion by all corrosive substances. It can also be used in conditions with sudden temperature changes, thanks to its good deformation properties. However, its operating temperature ranges only from -160°C to 250°C; care should be taken when using it at temperatures approaching 200°C or possibly above 250°C, in order to preserve its integrity. Hastelloy C276: Generally, the inner ring, outer ring, and central seal ring are all made of Hastelloy alloy C276 material, with the central seal ring coated in polytetrafluoroethylene or graphite. Graphite is easy to deform, but it can withstand high temperatures of up to 3000°C, and it also has good sealing properties. It is generally used in the distillation section of acetic acid systems, where there are certain oxidizing substances present. The price of C276 is relatively low among special materials, and it can also be used in oxidizing media. Hastelloy B3: This type of metal wound gasket is relatively rare, as Hastelloy alloys are used in low-pressure systems, with typical maximum operating pressures of less than 150 lb. Therefore, this special type of gasket is most often replaced by PTFE gaskets; data shows that some PTFE gaskets can withstand maximum operating pressures of up to 6 MPa. The inner ring, outer ring, and central seal ring of this special-type gasket are all made of Hastelloy alloy B3 material, with the central seal ring being coated with polytetrafluoroethylene or graphite. The material is cheaper than zirconium, but more expensive than Hastelloy alloy C276. Its corrosion resistance lies between that of zirconium and C276; however, it cannot be used in environments with oxidizing media. Therefore, it is generally employed in the synthesis sections of acetic acid systems, in media protected by reducing substances. Regular metal wound gaskets: 304L metal wound gaskets: These are very rare in acetic acid applications; generally, the material used for the inner ring and the central sealing ring is SS304L, with polytetrafluoroethylene or graphite wrapped around the central sealing ring. The outer ring is made of stainless iron, and it either has or is coated with an anti-corrosion coating, which can be easily identified with the naked eye. 316L metal wound gasket: The most common type of metal wound gasket in this industry; generally, the material used for the inner ring and the central sealing ring is SS316L, with polytetrafluoroethylene or graphite wrapped around the central sealing ring. The outer ring is made of stainless iron, and it may have an anti-corrosion coating applied to it. Ordinary metal wound gaskets: These are also extremely rare in such applications. The inner ring, outer ring, and central sealing ring of these gaskets are all made of stainless steel; the central sealing ring is usually coated with graphite. They are suitable for environments with low corrosion levels and high pressure requirements. Under normal circumstances, for convex-sealed flanges with a surface roughness of Ra6.0~10.0, it is recommended to use non-metallic gaskets for sealing (with different pressure ratings depending on the thickness); whereas for surfaces with a roughness of Ra3.0~6.0, metal wound gaskets are recommended. Generally, the pressure rating of metal wound gaskets varies depending on the width of their outer ring. For specific use, please refer to the design specifications provided by the chemical engineering design institute as well as the manufacturer’s instructions. Due to overheating some time prior to acetic acid production, most special materials were in short supply, resulting in a tight supply situation and making it difficult to purchase these special materials. It can be said that special materials were not something that could be bought with money at that time. Since the production of many special materials is still within the patent period, only certain foreign manufacturers are able to produce them. There are few domestic suppliers as well, so it should be quite easy to find information on them. However, as this relates to trade secrets, no details can be disclosed

Are you in the gasket business? If so, you can contact me on QQ609088064

Currently, there are quite a number of manufacturers in China that produce gaskets made from special alloys such as zirconium and C276. The purchase of thin strips of zirconium and 276, however, takes some time

If you need to know more, feel free to contact me. 　　baoseti@sohu.com I am from the US Huachang China representative office

The main materials used in acetic acid production are zirconium, titanium, and 316L

I have experience using Hastelloy materials, which were applied as gaskets in the Danyang acetic acid project. This post was last edited by scholar on 2009-4-4 10:15]