Correlation and capability of using site inspection data and small specimen creep testing for a service-exposed CrMoV pipe section

ABSTRACT

This paper presents for the first time an investigation on the creep damage evolution of an ex-service CrMoV pipe section through impression creep test (ICT) and metallurgical inspection data. The study emphasises the importance of correlating the operating conditions (temperature and stress) of power plant components with the results from metallurgical examinations and small specimen creep tests. The paper seeks for a correlation among micro- and macro-hardness measurements, surface replicas data and minimum creep strain rates (obtained by ICTs) of the parent material of the pipe section. Also, optical and scanning electron microscope (SEM) micrographs have been used to assess possible metallurgical differences through the thickness of the pipe section. This investigation shows how miniature creep test specimen data could be practically used in a holistic approach for the evaluation of life consumption of power plant components and concludes that the studied parent material could have been retired from service too early.

KEYWORDS:

• CrMoV pipe
• hardness
• impression creep
• replica
• site inspection data

Acknowledgements

This work is supported by the Engineering and Physical Sciences Research Council (EPSRC) through the Flexible and Efficient Power Plant project (Flex-E-Plant): [Grant Number EP/K021095/1]. We also thank the following partners for their valuable contributions: GE Power, Doosan Babcock Limited, Centrica plc., EDF Energy (West Burton Power) Limited, Uniper Technologies Limited, Goodwin Steel Castings Limited, NPL Management Limited, R-MC Power Recovery Limited, RWE Generation UK plc., Scottish and Southern Energy (SSE) plc., Siemens Industrial Turbomachinery and TWI Limited.

The authors would like to acknowledge the Flex-E-Plant consortium and EDF Energy for permission to publish this paper and also Mr Shane Maskill (the University of Nottingham) for his expert assistance in experimental testing and Mr Mike Goodbun (RWE Generation UK plc), Mr Bin Azahari Ahmad (the University of Nottingham) and Dr Xu Xu (the University of Loughborough) for their help and support on material characterisation of the present paper.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Engineering and Physical Sciences Research Council: [Grant Number EP/K021095/1].