Critical piping systems of a 500 MW super thermal power plant were analysed by ProSIM (www.pro-sim.com) for structural integrity.  Study included MS, HRH, CRH, HPBP, LPBP pipelines.  Plant was in service for more than 25 years.  Study conducted by ProSIM to a primary EPC contractor included site inspection, data collection on site, comparison of the design drawings with as as-is-where-is condition of the plant piping, conducting finite element analysis (FEA), analysis of effect of defects including microscopic defects, corrosion effects, and weld defects / discontinuity.