Acrylic Plastic Spherical Pressure Hull for 2439 m (8000 ft) Design Depth: Phase I

Abstract

A program has been initiated to provide the oceanographic community with a manned submersible with panoramic visibility for 2439 m (8000 ft) design depth. The first phase of the program is to validate the design of the acrylic plastic pressure hull utilizing model scale spheres with different diameters and thickness to inside diameter (t/Di) ratios. This papers summarizes 1) the criteria used in the design of the acrylic plastic hull for 2439 m (8000 ft) depth, 2) the experimental test plan for validation of the hull design, and 3) the fabrication, and short-term pressurization to destruction of the first scale model with an aluminum hatch. The 457-mm (18-in.) o.d. acrylic sphere with t/Di ratio of 0.2 successfully withstood 1-hr long pressurizations from 0 to 6.9, 13.8, 20.7, 27.6, 34.4 and 41.3 MPa (1000, 2000, 3000, 4000, 5000, and 6000 psi) followed by 1-hr long relaxation periods after each pressurization prior to imploding at 110.2 MPa (16,000 psi) under 4.5 MPa/min (650 psi/min) pressurization. The selected t/Di ratio 0.2 appears to exceed the design depth requirement for 2439 m (8000 ft).