Experimental investigations on a model of a power plant flange under steady state and transient load

ABSTRACTThe design and operation of conventional power plant components is affected by load changes, with the balancing of renewable energy generation leading to an increase in warm and hot starts. Essential parts of these power plant components are flanges e.g. connecting pipes and turbine housings. While being structural rather simple, many influences affect the functionality of these flanges, like the high-temperature behaviour of the bolt material or the temperature distribution in the components. This paper presents parts of a recently finished research project on different influences on the relaxation behaviour of flanges. To investigate the influence of the bolt material, tests were carried out on a model of an IP turbine flange using martensitic X12CrMoWVNbN10-1-1 and nickel-based Ni80A bolts. Each tests included 2000 h of steady state and 3000 h of transient load with a retightening of the bolts after 1500 h. Exemplary relaxation tests on the X12 material provide additional information towards the observed behaviour in the flange tests.KEYWORDS: Stress relaxationcreepturbine flangetransient loadsretightening of boltscomponent testhigh temperature testing AcknowledgmentsThe presented results were obtained at MPA Stuttgart within a research project carried out in the industrial collective research programme (IGF No. 20088 N). It was supported by the Federal Ministry for Economic Affairs and Climate Action (BMWK) through the AiF (German Federation of Industrial Research Associations eV) based on a decision taken by the German Bundestag. The authors would also like to thank the research partners from the IfW Technical University of Darmstadt and the experts from member companies especially from GE Power GmbH, Siemens Energy Global GmbH & Co. KG und MAN Energy Solutions SE for their contributions in the project working group and the provision of various benefits in kind.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work was supported by the AiF Projekt [20088 N].