Abstract: The present invention is directed to the formation of pressure resistant buoyancy structures with a given buoyancy efficiency at smaller sizes. The invention involves embedding into syntactic foam metallic spheres which preferably are substantially hollow and comprise high strength, high performance, light weight metal alloys which can be precision forged. The weight per unit space of the metallic spheres is less than that of the syntactic foam. As a result, the metallic spheres can decrease the size of the structure required to achieve a desired buoyancy efficiency.

Abstract: A method for making a reinforced pipeline comprising determining the thicknesses of a metallic liner and a reinforcement which are effective to limit stresses on a reinforced pipeline at a known operating pressure to a known percentage of the specified minimum yield strength and a known percentage of at least one actual yield strength along the length of the pipeline which differs from the specified minimum yield strength. Preferably, the reinforced pipeline is pressurized to produce yielding which results in a residual stress pattern effective to resist ductile fracture propagation along a longitudinal axis of said metallic liner along a length of the pipeline comprising at least two actual yield strengths.