Power pipe caps, also known as inner stoppers or inner plugs for power pipes, are widely used, easy to install, and commonly found in people's daily lives.

Pipe caps for electrical conduits, when in hot solvents, some thermoplastic plastics will be attacked and dissolve, such as polyethylene dissolving in xylene. Thermosetting plastics cannot be dissolved in solvents. As a source of rapid industry development, the plastic bottle cap industry has great potential. For products with high requirements, such as electrical conduit plugs and inserts, when using solid powder or granular additives, the grinding must be done on a three-roll mill equipped with plasticizers and plastic valve caps.