PIPING STRESS ANALYSIS AND
FINITE ELEMENT ANALYSIS (FEA) FOR CREEP ASSESSMENT

In order to precisely simulate actual conditions of the systems, a strain hardening material model was considered in creep analysis to implement creep strains effect. Moreover, inelastic properties of the material (plasticity) were also taken into consideration, defining such properties as variables based on temperature.

Creep damage assessment was performed according to the API 579-1/ASME FFS-1 by means of Finite Element Analysis (FEA). The analysis sequence included:

1. Previous damage characterization (corrosion, cracks, ovalities,…)
2. Material characterization (plasticity + creep proprieties)
3. Consideration of cyclic operating conditions, based on operational history.
4. Obtaining results of Stress and deformation states: damage assessment due to creep-fatigue plastic collapse and/or ratcheting