Improvements to the External Corrosion Direct Assessment Methodology by Incorporating Soils Data

To enhance the external corrosion direct assessment (ECDA) process, this project evaluated whether soils data could be used in a model to predict locations where external corrosion would be an issue. If by adding soils data to the previously collected ECDA datasets it could be shown that areas suffering corrosion could be predicted consistently, then operators would have an additional tool at their disposal to help maintain the country’s natural gas pipeline infrastructure safely and reliably. The approach targeted soils-corrosivity, because if corrosivity dominated a very simple model would be viable as a screening tool – with such a model then viable when other data are not available, unreliable, or difficult to obtain. Soil corrosivity was characterized in terms of a model that couples soils type with topography and drainage, with consideration also given to a simpler approach based on pH and resistivity. The results indicated that there is essentially no correlation between corrosion susceptibility based on soils-corrosivity expressed in terms of these two models. While an attempt was made to calibrate these measures of susceptibility using ILI data for corrosion incidence and severity, the frequency of corrosion for the sites evaluated was limited, which confounded this process. Important conclusions include: 1) little correlation existed between external corrosion and soils corrosivity for six sites. It follows that corrosivity cannot be viewed as a dominant factor controlling corrosion susceptibility; 2) the lack of correlation is not surprising given the effectiveness of cathodic protection (CP) and coating integrity at the six sites evaluated; 3) soils models to guide ECDA must consider CP and coating integrity; 4) the observation that local corrosivity is not important if the coating and/or CP system is working well indicates sites for ECDA should first be chosen in regard to CP history to identify areas where CP is effective and/or the coating functional in contrast to areas susceptible to corrosion; and 5) where the ECDA process identifies deficiencies in either coating or CP, then higher level measurements of corrosivity (e.g., resistivity) will likely suffice to decide locations for further examination as part of the ECDA process.

• Record URL:
  https://primis.phmsa.dot.gov/matrix/FilGet.rdm?fil=2187&s=6894241545A047269601D7AFD7396D98
• Summary URL:
  https://primis.phmsa.dot.gov/matrix/PrjHome.rdm?prj=118&s=6894241545A047269601D7AFD7396D98
• Supplemental Notes:
  • Title on cover: Improvement of External Corrosion Direct Assessment Methodology by Incorporating Soils Data. Date on cover: November 2005.
• Corporate Authors:

  Battelle

  505 King Avenue
  Columbus, OH  United States  43201-2693

  Pipeline and Hazardous Materials Safety Administration

  Department of Transportation
  East Building, 2nd Floor, 1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Leis, B N
  • Clark, E B
  • Lamontagne, M
  • Colwell, J A
• Publication Date: 2005-10-1

Language

• English

Media Info

• Media Type: Digital/other
• Edition: Final Report
• Features: Appendices; Figures; References; Tables;
• Pagination: 85p

Subject/Index Terms

• TRT Terms: Cathodic protection; Coatings; Corrosion; Corrosive soils; Natural gas pipelines; pH value; Soil types
• Uncontrolled Terms: External corrosion direct assessment process; Soil resistivity
• Subject Areas: Maintenance and Preservation; Pipelines;

Filing Info

• Accession Number: 01651128
• Record Type: Publication
• Contract Numbers: DTRS56-03-T-0003
• Files: TRIS, ATRI, USDOT
• Created Date: Nov 20 2017 4:45PM