A lightweight high pressure repairable piston composite tie-rod accumulator that does not use a load bearing metallic liner. An exemplary accumulator includes composite tie rods that sustain the axial stress induced by pressurization of the accumulator, while the shell is designed such that it sustains the stress of pressurization in the hoop direction. The tie rods can be secured using a wedge-type tie rod retention mechanism. As a result, no pretension is applied to the tie rods and the composite shell may be designed entirely for hoop stress.