PR335-233813-R01 Prioritization Methodology for Hard Spot Manufacturing Anomalies

This report describes a methodology for evaluating pipelines containing hard spot manufacturing anomalies and prioritizing such anomalies identified from In-Line Inspection (ILI). It is reported here to evaluate and enhance ILI tool technology and analysis capability to reliably detect, size, and quantify the pipeline integrity threat posed by hard spot manufacturing defects that have led to notable industry failures. This report covers one task of the project which is development of a specific methodology for evaluating the predicted failure pressure (PFP) of cracking that initiates in pipe body hard spots. A deterministic method is provided that details a process for evaluating whether a hard spot with a crack that has initiated will rupture as a function of hard spot size, pipeline pressure, temperature and base material toughness outside of the hard spot. This method was developed to assist in prioritizing hard spot defects identified from ILI results for further excavation and remediation.

Using the PFP evaluation methodology, an approach for completing a probabilistic evaluation was then developed. The probabilistic evaluation considers environmental and material factors which may make a crack likely to initiate in a hard spot and considers ILI tool uncertainty. The probabilistic method provides insight on the level of risk reduction that would be achieved through excavation and/or remediation activities in response to hard spot ILI results.