Composite vessels for high pressure gas storage are commonly used these days because of their competitive
weight reduction ability maintaining strong mechanical properties. To supplement permeability of composite
under high pressure, it is usually lined by metal, which is called a Type 3 vessel. However, it has many
difficulties to design the Type 3 vessel because of its complex geometry, fabrication process variables, etc. In
this study, therefore, GUI (graphic user interface) optimal design code for Type 3 vessels was developed based
on semi-geodesic algorithm in which various factors of geometry and fabrication variables are considered and
genetic algorithm for optimization. In addition, hydrogen vessels for 350/700 bar that can be applied to
FCVs(fuel cell vehicles) were designed using this code for verification.