LIFE ASSESSMENT EVALUATION OF PIPING BRANCH CONNECTION UNDER CREEP AND FATIGUE

The comparative results of fatigue life assessment analyses are presen ted for piping branch connection of Tee type (Tee) of power station ma in steam piping. The results are derived using the German Standard TRD approach with and without usage of modified finite element analyses o f transient thermal stresses, occurring during power station startup o r shutdown. The traditional TRD approach for Tee stress analyses is co nservative due to the use of formulas which are the upper estimate of transient thermal stresses. The TRD assumption about the coincidence o f creep and fatigue maximum stress areas is very conservative as well. The analyses results enable us to extend the power station piping com ponents life assessment. (C) 1997 Elsevier Science Ltd.