Final Report on Improvements to the External Corrosion Direct Assessment (ECDA) Process (WP # 360) Potential Measurements on Paved Areas (Project #243)
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2010-06-01
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Alternative Title:Improvements to the External Corrosion Direct Assessment (ECDA) Process Potential Measurements on Paved Areas
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TRIS Online Accession Number:01640949
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Edition:Final Report
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Abstract:On June 28, 2007, PHMSA released a Broad Agency Announcement (BAA), DTPH56- 07-BAA-000002, seeking white papers on individual projects and consolidated Research and Development (R&D) programs addressing topics on their pipeline safety program. Although, not specifically suggested by PHMSA, three Direct Assessment projects were proposed by Corrpro based on an in-house gap analysis of the External Corrosion Direct Assessment (ECDA) process. A white paper was submitted for a consolidated Research and Development (R&D) program entitled "Improvements to the External Corrosion Direct Assessment (ECDA) Process". It was eventually approved for implementation by PHMSA with the following 3 projects: - Cased pipes - Severity ranking of ECDA indirect inspection indications - Potential measurements on paved areas The ultimate goal of each of the programs was to present the results and recommendations to the applicable Standards Development Organizations (SDOs) to ensure the strengthening of industry consensus standards and the timely implementation of research benefits for improved safety, environmental protection, and operational reliability. It was also to expand DA applicability and increase the knowledge of the DA methodology. The accomplishments and conclusions of the research on potential measurements on paved areas are summarized as follows: - Gravel & Asphalt: - Simple, straightforward pre-survey surface resistance measurements can be used to determine if on-pavement potential surveys will yield accurate results - A surface resistance threshold of ~2x105 ohm-ft2 has been determined, i.e. standard potential measuring procedures can be used with reference electrodes on the paving when surface resistances are less than this value - A standard 3" diameter reference electrode with wetted towel or sponge is adequate to minimize the effect of contact resistance - Concrete: - No clear, consistent method for making accurate pipe-to-soil potential measurements was determined, other than through the use of drilled holes - Future research is in order to evaluate the feasibility of accurate DCVG and or ACVG measurements with reference electrodes placed on the concrete surface
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