PP Tanks are made with the thermoplastic polymer used in a wide variety of applications such as the manufacture of chemical storage tanks. Polypropylene tanks, which fall into the broad categorization of plastic or poly tanks, are all-purpose containers invented from a typical thermoplastic chemical compound. Polypropylene chemical tanks could be a lightweight, durable thermoplastic that's denser, stiffer, and stronger than polyethylene and also includes a high melting point.