This paper concerns with the aspects of the Object Oriented Programming used to develop a Finite Element technique for limit analysis of axisymmetrical pressure vessels. The concepts of inheritance, polymorphism, encapsulation and modularity are extensively explored. The analysis processor is part of a global computation system and it is integrated with two graphical modules defined as modeler (preprocessing) and post-processor, both of them associated to a new CAD technology. The problem used to illustrated the limit analysis technique implemented is a standard ASME torispherical vessel subjected to internal pressure. The obtained results are compared with other numerical and analytical solutions.