Should tool tolerances be considered when determining if a detected anomaly meets repair criteria?
Yes. Operators are required to integrate relevant information on the condition of the pipeline in making decisions on excavation timing and other mitigative actions. Tool tolerances should be considered as part of the data integration process. Information on tool tolerances should be used to assure that defects requiring early excavation and mitigative action are properly identified and characterized. This does not necessarily mean simply adding the vendor-supplied tolerance value to reported depth of indications. Several sources of data may be used, in conjunction with vendor-supplied tool tolerances, to characterize pipeline defects. These include results of previous excavations, confirmation digs, results of concurrent inspections, and comparison to prior inspections. Uncertainties in this data should also be considered. In addition, information on tool tolerances may be incorporated in engineering analysis such as “probability of exceedance” to help operators prepare a comprehensiv
