Abstract: A filament-reinforced resin-impregnated hollow body having at least one internal circumferential strengthening flange or rib is fabricated by winding a first filamentary winding on each of two mandrel portions, the filament being wound across at least one end of each portion so that the winding extends inwards towards the axis of each mandrel portion. With these two ends spaced opposite one another, a second filamentary winding is wound between the inwardly extending parts of the first winding. A third winding is then applied over the first and second windings. After curing the resin-impregnated windings, the mandrel is removed, leaving an internal flange formed by the inwardly extending parts of the first winding in conjunction with the second winding.