Fitness-for-Service Assessment for Pressurized Components with Geometric Distortion

Fitness-for-Service (FFS) is a set of quantitative methods used to determine the
integrity and remaining life of degraded components. Structural integrity of a
pressurized component can be put at risk with the presence of geometrical
discontinuities. FFS assessment is carried out based on API 579 code of practice to
determine if equipment is safe and fit for continued service until the end of some
desired period of operation. The objectives are to study and understand the FFS
procedures covered in Section 8 of API Recommended Practice 579, as well as
performing Level 1, Level 2, and Level 3 assessment procedures for cylindrical shell
with out-of-roundness as per API 579. The project was further expanded by
comparing data from the FFS assessment procedures with ANSYS simulation, a
Finite Element Analysis (FEA) software to evaluate the acceptance criteria. The
project demanded multi disciplinary engineering practice, ranging from applying
codes and standards, solving case study, as well as computer simulation. The scope
of work was targeted on out-of-roundness in terms of dent. The final step of this
project would be comparing all analysis done on the model with FFS assessment for
verification. Based on the results obtained, reference stress used for failure criteria
for FFS Level 2 Assessment is based on the yield strength of the material of the
structure.