of the rings and how they work are described in u s pat no 5 286 040 by gavin u s pat no 5 286 040 is hereby incorporated by reference wall 100 arcs outward having a lower radial thickness than wall 102 or 104 provides a moderate sealing force and provides room for diametric expansion of wall 104 wall 104 is shown in fig3 and 4 operating as an annular interface 124 it is shown operating as an annular interface 124 on a major diameter 142 and on a minor diameter 144 having a radial thickness equal to radial height 152 wall 104 has high resistance to diametric expansion it expands normal to axis 110 contributing a high sealing force wall 104 can also crush and rotate slightly about annular connecting joint 156 cast in concrete seal 160 in fig5 has annular interfaces 164 and 168 provided by radial walls 172 and 174 respectively which apply a higher total sealing force on pipe 176 referring to fig1 and 9 cast in concrete seal 180 holds pipe 54 in asymmetrical opening 184 through the seal of radial wall 186 the asymmetrical opening was provided by removing section 192 of the seal within weakened annular separation ring.