Erweiterung einer Finite-Elemente-basierten Methode zum normkonformen Festigkeitsnachweis von unbefeuerten Druckbehältern

Translated title of the contribution: Extending a finite-element based method for a standardized strength assessment of unfired pressure vessels

Dorothea Beck-Mannagetta

Research output: ThesisMaster's Thesis


One of the referred standards of the European Pressure Vessels Directive is the EN 13445 for unfired pressure vessels. The aim of this master thesis is to set up an automatic calculation of local degrees of utilization according to this standard in the software package “IBF-Fatigue” of Ingenieurbuero Fiedler GmbH based on linear elastic calculated finite element stress results. The different assessment methods of EN 13445 are analysed regarding the applicability for given 3D CAD models, the applicability based on linear-elastic calculated finite element stress results as well as the scope and prerequisites for the application of the standardised design methods for a static, fatigue strength assessment and for an assessment in the creep range. For each selected method, a calculation procedure is implemented in a mathematic program. Finally, by carrying out test calculations for welded and unwelded areas of an exemplary pressure vessel, the results according to EN 13445 are compared with the FKM guideline "Calculated strength analysis for machine components" for local stresses. The in-depth comparison of the test calculations with the FKM guideline shows that the most important difference between the static test calculation of the FKM guideline and EN 13445-3 is the stress classification according to EN 13445. This allows dividing the effective stress by 1.5 times the allowable stress and thus results in 2 to 29% lower degrees of utilization according to the EN 13445 than to the FKM guideline. The fatigue strength test calculations in FKM guideline are based on a material safety factor of 1.25, which leads to lower allowable stress ranges than EN 13445. The total degrees of utilization of the fatigue test calculations in welded areas differ mainly due to the different used values of FAT-classes. For the calculation in the creep range, the most important difference between the FKM guideline and EN 13445 is the allowable stress, which is 53 to 92% higher in the FKM guideline than according to EN 13445. This deviation causes the additional weld factor of EN 13445 in the creep range of 0.8 and the different values of the material safety factors in creep strength assessment. In detail, the FKM guideline recommends a safety factor of 1.072 for welds and 1.057 for base material and EN 13445 states a factor of 1.5 for welds as well as base material. This results in 12 to 22% higher degrees of utilization in the creep range according to EN 13445 than according to the FKM guideline.
Translated title of the contributionExtending a finite-element based method for a standardized strength assessment of unfired pressure vessels
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Stoschka, Michael, Supervisor (internal)
  • Leitner, Martin, Co-Supervisor (internal)
  • Fiedler, Georg, Supervisor (external), External person
Award date23 Mar 2018
Publication statusPublished - 2018

Bibliographical note

embargoed until 15-03-2023


  • EN 13445
  • finite-element
  • strength
  • assessment
  • pressure
  • vessel
  • unfired
  • IBF-Fatigue
  • fatigue life
  • creep strength
  • creep range

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