It is a Monel alloy butterfly plate with polytetrafluoroethylene (PTFE) embedded on it to help seal.

The valve stem is externally threaded and has a bracket

The packing is GRAFOIL, which is the name of a company's registered trademark. You can search the company's website using Google or Baidu.

Monel alloy is a high-nickel alloy, its main components are smelted from 64 to 70 nickel and 26 to 33 copper. Because nickel alloys easily absorb gases, mainly H2, CO and other gases, this further causes dispersion and shrinkage, resulting in "hornet's nest" defects. In severe cases, they will connect to each other and penetrate the entire casting. Coarse grains promote the precipitation of impurities in the grain boundaries that cause dendrite shrinkage, which is a big problem in Monel alloy casting. To solve this problem, a series of measures such as advanced vacuum smelting and vacuum casting are currently adopted.

Monel alloy valves are resistant to hydrofluoric acid (HF), uranium fluoride (UF6, UF4), dilute sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, strong alkaline solutions, salt water, seawater and halogen elements. It has excellent corrosion resistance, so it is widely used in key parts of the pipeline systems of large modern enterprises such as petrochemical industry, petroleum refining, atomic energy industry, and pharmaceutical industry.