A pressure vessel assembly, and method of use, for storing a gas at an elevated pressure. The assembly includes a vessel body having a rigid wall with an inner surface defining a storage chamber and with an inlet allowing the gas to enter the storage chamber. The assembly includes a flexible liner positioned within the storage chamber to be in fluid communication with the inlet to receive any fluid entering the vessel body. The liner is formed of an elastic inner layer contacting the gas and a metallic outer surface. The inflated, unrestrained liner volume is generally at least as large as the chamber volume and more typically, slightly larger. Stored gas contacts the inner surface of the liner and expands the liner from a smaller deflated volume until the outer surface of the liner contacts the wall of the pressure vessel.