of the rectangular panels 12 results in spaces 48 being created near the edge of the tank these spaces are caused by the insulation panels not perfectly aligning with the curvature of the tank in order to cover the spaces 48 circumferential panels 32 shown in fig4 are utilized the circumferential panels 32 have an upper side 34 a lower side 36 an inside edge 38 an outside edge 40 a left edge 42 and a right edge 44 the circumferential panels 32 are located near the edge of the tank and float on top of the rectangular panels 12 that have already been installed the inside edge 38 is positioned toward the center of the tank while the outside edge 40 is positioned near or on the edge of the tank left edge 42 and right edge 44 of circumferential panels 32 have locking rim 28 the locking rim 28 of circumferential panels 32 can be designed similar to the locking rim 28 used on the rectangular panels 12 the locking rim 28 of circumferential panels 32 also defines a locking channel 30 which allows one circumferential panel 32 to become engaged with an adjacent circumferential panel 32 this prevents the circumferential panels 32 from moving apart.