Study on random vibration fatigue evaluation method of small branch pipe welded joints in nuclear power plants
YANG Jiandong
GAO Hongbo
XU Yangyang
ZHOU Shuai
LIN Lei
PENG Liang
SHI Hongxing
LUAN Zhenxing
ZHAO Yue
Abstract：[Objective]Aiming at the fatigue life evaluation of welded joints of small-bore pipes in nuclear power plants under random vibration loads,fatigue life evaluation methods based on test data,the in-service fitness-for-service(FFS)assessment method specified in ASME FFS-1 and the equivalent structural stress method were investigated.[Methods]The fatigue life evaluation approaches based on test data,ASME FFS-1 fatigue analysis method and equivalent structural stress method were compared,and comparative verification was conducted via random vibration fatigue tests.[Results]The research results reveal that the ASME FFS-1 fatigue analysis method is susceptible to mesh sensitivity when dealing with complex structures,which may lead to excessively conservative fatigue life evaluation results.The fatigue analysis method based on measured stress also presents high conservatism and may cause unnecessary increase in maintenance costs.In contrast,the equivalent structural stress method can more accurately take into account the local stress concentration effect of welded joints,effectively adapt to complex random vibration environments,and possesses higher prediction accuracy and engineering applicability in fatigue life prediction.It can provide an important reference for formulating effective preventive maintenance strategies.
Keywords：Small branch pipeWelded jointRandom vibrationEquivalent structural stressFatigue life
Publication Date：2026-06-30
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：7( 110-116 )