This paper sets forth guidance on how to establish a justifiable internal corrosion rate following a first time inspection to predict re-inspection or replacement timing for raw water piping. A novel approach leverages actual plant-wide piping inspection data, leak history, repair history, and corrosion monitoring results together to inform integrity decisions based on experience at a reliably-operating, nuclear power plant. Data is applied on a risk-conscious basis to piping systems based upon failure consequence and uncertainty and differs from the typical approach of reporting location-specific, time-averaged rates. Excavation and in-plant inspection results can now inform commercially-friendly conservatism that reduces leak risks while also minimizing total inspection and maintenance costs.
While directly applicable to buried piping, this method can be applied to any corrosive system / location. Information is presented in a format that readers can readily follow to develop similar justifications for their own sites / systems. Guidance on applications, limitations, and areas for improvement are also provided.