PEX is a type of petrochemical industries derived from petroleum, specifically from Ethylene, which is a gas, means or granules, which are symbolized by a scientific letter (PEX), and when this material is heated and placed under a certain pressure, its composition changes from ethyrene to polyethylene. The polyethylene and other plastics such as polystyrene belong to a group called thermoplastic, these materials soften at certain temperatures, and if the process of determination of heat is repeated,these materials lose their mechanical properties, which makes them lose their validity for use.