Steam Turbine Risk Assessment - A Tool To Assist In Optimizing Inspection And Overhauls Of Industrial Steam Turbines.

Abstract

There are currently no-or at best, very limited-industry guidelines or requirements on which to quantify the risk associated with turbine inspection intervals. Insurance industry data indicate that steam turbines are a major machinery loss item with underwriters. Thus, there are clear incentives to develop better tools within the industry to optimize the overhaul and inspection requirements for steam turbines. A steam turbine risk assessment project was initiated to develop a methodology to address the issue of optimization of overhauls by identifying and quantifying the risk associated with maintenance, operation, and engineering. Furthermore, this risk is related to the economic impact of the decision. The methodology followed is an adaptation of ASME RiskBased Inspection Guidelines. This process, in principle, has been previously applied in the petroleum industry for pressure vessel inspection. The process consists of five steps: • System definition • Qualitative risk assessment • Quantitative risk analysis, which includes failure modes, effects, and criticality analysis (FMECA) • Inspection program identification • Economic optimization. The result is incorporated into a computer model that will permit scenarios for individual turbines to be evaluated on a cost-riskbenefit basis. Beta testing is scheduled to begin in third quarter 1997.