The experience gained by PETROBRAS over eleven years operati ng several floating product ion systems based on extensive use of flexible pipes, indicated that such a concept was a reliable alternative for deep water exploitation. To properly predict the behavior of flexible pipes in deeper water applications, more sophisticated analysis tools are naturally required. For such a reason, TUBFLEX, a P.C. program was recently developed in cooperation with the Federal University of Rio de Janeiro. TUBFLEX takes into consideration two distinct mathematical models for pipes with either bonded or unbonded layers. Basically the input data cons1st in the follow1ng: mechanical characteristics of the layers (geometry and material propert1es), loading condition (internal and external pressure, tension, torsion, bending moment or imposed bending radius) and boundary conditions. Pipe global strains, ultimate stress conditions and pipe stiffness are typical output data. Both mathematical models are described and examples of practical applications are presented. Different concepts of pipe design are analyzed and output results are compared. Finally, some important points where PETROBRAS is making efforts to optimize the use of flexible pipes are presented.
Almost four years ago PETROBRAS decided to act more directly 1n the flexible p1pe market not only as a client, but trying to influence the market as a major consumer. In fact, PETROBRAS is the largest client of flexible pipes in the world and more than a half of the total footage of flexible pipes already produced is installed in Brazil. Additionally, that material represents one of the most expensive items for developing satellite fields in the Campos Basin (from 25% to 50% of the overall investment). Moreover, flexible pipes represent a vital component of deep water floating production systems.