Comparing Near-Field Electromagnetic Inspection Tools

Near-field electromagnetic inspection of prestressed concrete cylinder pipe (PCCP) water transmission mains and pressurized sewer mains has become the best practice in the proactive management of these assets. This nondestructive testing method reports the location and approximate quantity of broken wire wraps on individual pieces of pipe in a PCCP main. Until 2022, there was only a single provider of such services. Now, multiple providers are offering this service, providing end users increased competition and its associated benefits. To realize benefits from increased competition, the efficacy of new technologies and the inspection results from the providers must be trusted. To determine the efficacy of new providers, the authors reviewed data from two inspections to evaluate if a new technology provider is producing results consistent with other inspection methods. In one inspection, the pipeline was inspected by a long-term provider of these services and by a newer provider. For the second inspection, the broken wire wraps data was compared with visual and sounding inspection results, specifically for pipes exhibiting visible evidence of deterioration. A comparison of results between the experienced and new technologies is provided. The comparison focuses on two variables: (1) Identification of pipes with broken wire wraps and (2) Variability in the quantification of the number of broken wire wraps.