Why can’t copper be used for vinyl chloride equipment, pipes, etc.?
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I just came across a statement stating that for equipment, pipes, valves, and instruments in contact with vinyl chloride, steel, cast iron, or cast steel materials should be used; the pipes carrying vinyl chloride before it enters the reactor should be made of stainless steel. The use of copper, silver (including silver welding), or mercury is strictly prohibited. What is the reason?
The medium contains a certain amount of acetylene, and acetylene cannot come into contact with copper – this is determined by the properties of acetylene.
It easily forms copper acetylide; silver and mercury are highly explosive substances
The VCM monomer contains a small amount of acetylene gas, which forms compounds with metals such as copper and silver**
1. Acetylene reacts with copper, mercury, and silver to form metal acetylide compounds, which can explode even with slight vibration； 2. The liquid phase of VCM in the polymerization unit is mostly made of stainless steel, as the moisture content in the monomer can increase iron ions, thereby affecting product quality ；
The key is the content, which must not exceed 70%, as this can lead to the formation of copper acetylide and an explosive reaction. You can take a look at the national standard safety technical regulations for vinyl chloride using the acetylene method.
The VCM monomer contains a small amount of acetylene, and acetylene readily forms highly explosive compounds such as copper acetylide, silver acetylide, and mercury acetylide when it comes into contact with metals like copper, silver, and mercury