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

The owner of a steel plant in DURGAPUR (India) requested CADE to assess the remaining life and mechanical integrity of eight gas piping systems in a power generation cycle (60MVW), including the evaluation of hanger/support points and equipment terminal connections as well.

For this purpose, both flexibility analysis and subsequent stress analysis were performed in order to validate the following failure modes:  plastic collapse, ratcheting and creep-fatigue. Other identified issues  such as corrosion, ovalizations-deformations and cracks, directly related to the plant aging, were considered on this evaluation.

METHODOLOGY AND ANALYSIS

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

Results of analysis allowed to determine the accumulated damage due to creep-fatigue effect along  cyclic operational history of the plant, as well as the remaining life of the piping systems evaluated for current operating conditions.

piping system creep analysis

EXPERIENCE

CADE provides advanced engineering, simulation and consulting services for critical equipment, piping systems or structures when they are not operating as expected, when a mechanical or structural failure occurs, or when it is necessary to evaluate its mechanical integrity and remaining life. 

CADE Engineered Technologies

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