With which type of pipe can plastic cleanout plugs only be used?

Plastic cleanout plugs are designed to be used specifically with plastic piping systems because they provide a reliable seal and fit that is compatible with the material's properties. When installed in plastic pipe systems, these plugs help to maintain the integrity of the plumbing system while allowing for easy access for cleaning and maintenance.

Although plastic cleanout plugs can technically be compatible with metallic pipes, generally, this compatibility is not recommended due to differences in expansion, contraction, and potential corrosion issues that can arise when using plastic with metal. Therefore, while the initial answer suggests they can be used with both types, best practices recommend using plastic plugs specifically with plastic pipes where their design and material properties are optimized for dependable use.

Thus, understanding the use of plastic cleanout plugs primarily in plastic pipe systems highlights the importance of matching materials to ensure longevity and functionality in plumbing installations.