Improving Magnetic Flux Leakage In-Line Inspection Corrosion Sizing using Focused Guided Ultrasonic Waves

In-line inspection is an integral part of many pipeline company integrity management plans. The most common inspection technology for both natural gas and liquid pipelines is magnetic flux leakage (MFL). MFL was first used in the 1960's and was significantly improved in the 1980's and 1990's. While improvements are still being implemented, the performance capability of MFL tools has remained relatively unchanged for a decade. The major attribute of MFL is the ruggedness of the implementations that enable this technology to perform under the rigors presented by the pipeline environment. The most commonly reported deficiency of this technology is the lack of precision in reported sizes of the anomalies detected. The nominal depth sizing specification of most MFL in-line tools is a tolerance of +/-10% of wall thickness with a certainty of 80% (4 of 5 depth readings are within the tolerance). The depth of long narrow axially aligned anomalies are particularly problematic. The goal of this development is to improve corrosion anomaly depth sizing of MFL tools by adding a second complimentary technology, focused guided-wave ultrasonic inspection technology. An electromagnetic acoustic transducer (EMAT) sensor was developed to generate and receive the focused ultrasonic energy at the anomaly. The design has been tested in the laboratory and on pipe pulled from service at the Pipeline Simulation Facility. This EMAT sensor uses focusing to provide better resolution of the ultrasonic waves over commercially available implementations of EMATS used for pipeline inspection. Since anomalies are typically smaller than the lateral resolution of common sensors, detection can be good but sizing will be a challenge. Focusing of the guided waves generated by the EMATS can provide tight beam for interrogating pipeline anomalies. This project resulted in new technology to augment MFL tools for improved corrosion sizing. MFL tools would still be used to detect corrosion and provide typical sizing information. The guided wave technology will provide additional information for the better characterization of depth. The configuration developed on this program primarily addressed long narrow axially aligned anomalies. The improved accuracy provided by this in-line inspection technology will help pipeline owners better assess corrosion anomalies and more accurately determine corrosion growth rates to enhance their integrity management programs.

  • Record URL:
  • Corporate Authors:

    Battelle Memorial Institute

    Columbus, OH  United States 

    FBS, Incorporated

    143 Hawbaker Industrial Drive
    State College, PA  United States  16803

    Conoco Incorporated

    Houston, TX  United States 

    Pipeline and Hazardous Materials Safety Administration

    Department of Transportation
    East Building, 2nd Floor, 1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Nestleroth, J Bruce
    • Van Velsor, Jason K
  • Publication Date: 2010-9-30


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 64p

Subject/Index Terms

Filing Info

  • Accession Number: 01641066
  • Record Type: Publication
  • Report/Paper Numbers: G006084, N105348
  • Contract Numbers: DTPH56-08-T-000004, Project 232; SALAMMM
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 17 2017 9:32AM