Life and maintenance optimisation of reheater tubes


  • 2¼CrMo reheater tubes in a natural-gas fired 270MW power station with 40,000h service


  • To optimise the chemical-cleaning frequency, based on achieving a further 100,000h service


  • Probabilistic life assessment, centred on a mechanistic model addressing creep, fireside and steamside corrosion and using quantitative inspection data


Tube life shown to be sensitive to acid-cleaning interval
Cleaning every 30,000h shown to be required in order to achieve the desired life


  • Tube life determined
  • Optimum maintenance regime identified
  • Identification of a material upgrade, to 12%Cr, as a cheaper and less disruptive option than the three acid-cleaning operations required to achieve 100,000h
Effect of acid-cleaning interval on tube failure probability


Brear, J.M., Jones, G.T., Jarvis, P. and Sanders, J,
“On-line monitoring of power plant components”
ERA Conf ‘Engineering Asset Management for Utilities, Industry and Commerce’, London, 7-8 October 1997. Paper 3.7

Brear, J.M., Williamson, J., Cane, B.J., Jones, G.T. and Leavy, K,
“Predictive evaluation of superheaters and reheaters - a probabilistic treatment’
VGB, KEMA, CRIEPI, EPRI Int Conf ‘Life Assessment and Extension’, The Hague, The Netherlands, June 1988

Plant Integrity