Indexed on: 09 Mar '16Published on: 27 Sep '14Published in: International Journal of Mechanics and Materials in Design
This study presents a comparative evaluation of the various acceptance criteria in API579-ASME/1 fitness-for-service (FFS) code for equipment suffering from metal loss, using a case of severe corrosion in a pipe subjected to internal pressure and supplemental loads. All three assessment levels were conducted to evaluate the remaining life of the pipe under various acceptance criteria assuming constant corrosion rate. In particular, Level-3 assessment was performed using three-dimensional parametric limit finite element analysis to evaluate the remaining life. The model accounts for the observed metal loss, with the aim of evaluating the plastic collapse pressure of the corroded pipe. The remaining life was estimated using both global and local failure criteria and the conservatism of various methods and criteria is assessed. Results showed a potential trade-off of continued operation at the original design pressure for shorter period against a pressure de-rating procedure for extended operation.