Abstract: Improved multi-wall containers and pipes for transporting fluids which have to be protected against leakage and mechanical forces, have an inner and outer wall separated by a continuous foam layer integrated into the containers. Improved strength and resistance to axial inertial pressure is provided by the method of manufacture using chopped glass fibers, continuous windings of glass fibers and suitable polyester resins and circumferential ribs spaced at stress points and integrally incorporated into the containment walls. Vessels produced according to the methods of the invention have a moment of inertia strength of about 4.67 in.sup.4 substantially eliminating torquing, buckling and rupture.

Abstract: Improved multi-wall containers and pipes for transporting fluids which have to be protected against leakawge and mechanical forces, have an inner and outer wall separated by a continuous foam layer integrated into the containers. Improved strength and resistance to axial inertial pressure is provided by the method of manufacture using chopped fiberglass, continuous windings and suitable polyester resins and circumferential ribs spaced at stress points and integrally incorporated into the containment walls. Vessels produced according to the methods of the invention have a moment of inertia strength of about 4.67 in.sup.4 substantially eliminating torquing, buckling and rupture.