A filament-wound tank portion of an electric water heater has a wall opening
through
which an electric heating element of other structure extends into the interior
of the tank. The opening is reinforced by a stacked series of single layer, open
weave patch members which are interdigitated with layers of the filament winding
and through which the opening extends. The filament winding and the patches are
impregnated with and intersecured by a cured resin material. As an alternative
to cutting portions of the patches during formation of the tank wall opening, the
patches may be provided with suitable pre-formed openings with reinforced peripheries,
the subsequently formed tank wall opening extending through these reinforced, pre-formed
patch openings. The single layer, open weave patches are also utilized to reinforce
other types of filament-based tank wall structures.
