Abstract

A filament wound pressure vessel is disclosed and has a spherical shape including a polar opening with a fitting disposed in the opening and protruding therefrom. A plurality of layers of filaments are wound about the polar fitting. Each layer comprises a sequence of polar winding patterns wound with incrementally increasing wind angles away from the polar fitting, creating voids at the junctures of adjacent patterns near the polar fitting and thus between sequential layers at said junctures. One or more annular fill doilies are installed in annular regions about the polar fitting to fill the voids between the layers at the junctures of adjacent winding patterns. The doilies are circular in configuration with a central opening for installation concentric with the polar opening. Preferably, a plurality of the doilies of increasing diameters are installed to fill respective voids at the junctures of the winding patterns of increasing wind angles, with the larger of the doilies installed over the smaller doilies between the filament wound layers.