Abstract:
Risk Based Inspection method was employed for life assessment of 3RYSH superheater tubes in athermal power plant. Data collection related to the causes of corrosion attacked outside boiler tubessuch as operating conditions, materials selection, and fuel usage were used as parameters for lifeassessment of superheater tubes. The estimated values of remaining life were around 5-41 years.The 3RYSH superheater tubes having the lowest remaining life of 5 years located above 2RYSHsuperheater tubes and closed to the waterwall tubes were recommended to be annually inspected.Na and V in fuel oil, the main elements that cause oil ash corrosion, were detected in fire-side-oxidescales using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and X-ray Diffractrometry(XRD). Microstructures of 3RYSH superheater tubes were investigated using an optical microscopy(OM) and a scanning electron microscopy (SEM). The observed microstructures revealed precipitationof carbides at grain boundaries and porosity at the outer surface of the tubes. All evidences confirmed that the 3RYSH superheater tubes were attacked by oil ash corrosion.