What is a pressure test tank? A pressure test tank or a PT tank is a fabricated plastic tank that is filled with fluid in which hoses, assemblies, and other industrial parts are pressurized with air and submerged in order to test for and detect leaks. It is important to note that the tank itself does not withstand pressure or explosion; it serves as the vessel in which the test takes place. We make test tanks to your specifications. Most are made out of clear polycarbonate material. We also make polypropylene pressure test tanks, some with clear polycarbonate windows and some without.