Fumitoshi Sakata

Theoretical and Experimental Investigation of Pipe Wall Thinning Detection Using Guided Waves

A method to investigate pipe wall thinning using guided waves has been developed for pipes in thermal power generation facilities. In this paper, the reflection coefficient and the transmission coefficient are derived for the torsional waves which propagate along a pipe and a simplified method to predict the waveform is proposed. The predictions of the waveforms by the FEM and a simplified method based on the reflection of torsional waves are also examined by comparing with experimental data.Copyright

A New Heat Treatment Technology for On-Site Life Extension of High Energy Pipe Weldments Degraded by Creep Damage

This report presents the development of technology enabling temporary countermeasures for the on-site application of life-extending induction heating to high energy pipe weldments having experienced degradation due to creep. The results of an investigation into the cross-sectional structure thus suggested that material life can be extended by the application of regenerative heat treatment. The life-extending effect of regenerative heat treatment is greatest toward the short-life vicinity of the pipes outer surface, thus providing an efficient life extension. The remaining life converted for an actual installation from the result of real scale creep burst test increased from 63,000hrs before treatment to 200,000hrs after treatment, confirming that life can be extended by approximately 130,000hrs.Copyright