Definition - What does Perlite mean?
This is a volcanic glass material made by the hydration of obsidian, which is characterized by its ability to expand four to twenty times its volume when heated to a certain point in the softening range.
Its expansion ability and light weight makes it suitable for use as an insulation material and corrosion under insulation water filtration. It is basically used as a weather-proof metal jacketing system.
Corrosionpedia explains Perlite
The presence of water in the makeup of the material makes it produce bubbles in the particles when it is heated to a temperature above 870 degrees Celsius. Expanded perlite, in particular, is the one used in insulation.
When perlite is used as an insulation material, corrosion under insulation affects the substrate when moisture is retained. The hydrophobic nature of the perlite material makes it a suitable insulation to prevent the leaking of water into the hot substrate. Corrosion prevention is required when the temperatures are beyond the ambient temperature.
Perlite is used in conjunction with other materials and chemicals to prevent the presence of moisture in hot pipes.