Stiffened Cylinder Calculator This is a Microsoft Excel tool using ABS design rules to calculate the maximum pressure and depth for stiffened cylindrical hulls.   It also calculates depth ratings for hemi-spherical and semi-ellitical tank heads. Penetration & Opening Reinforcement A Discussion of Area Replacement Method in Opening Reinforcement Design Openings in ASME Code Pressure Vessels Using the ASME VIII-1 Nozzle F Factor (UG-37) Tank Heads 2:1 Elliptical Weight, Buoyancy, and Pressure Chart This spreadsheet provides the weight, displacement, buoyancy, and ABS pressure rating for common sized tank heads.