The Office of Pipeline Safety (OPS) of the US Department of Transportation requires all pipelines to be inspected regularly to ensure public safety. The reassessment interval currently in use was stipulated by OPS to be seven years, a single number regardless of differences in pipeline operational and environmental conditions. Since the reassessment interval can be determined by the size and the growth rate of a defect or a flaw in the pipeline and corrosion plays a key role, the goal of this work is to simulate mathematically the pipeline corrosion and compute the disbondment corrosion rate and potential. O2 is here assumed to be a dominant corrosive species. A simple algebraic equation and a corresponding simple measurement procedure have been developed. This procedure allows the pipeline operators to estimate conveniently the underneath corrosion potential and rate and can be considered for use in the external corrosion direct assessment procedure. It has been found that aerated crevice corrosion rate or potential with or without cathodic protection (CP) can be reproduced by simple anodic or cathodic polarization in deaerated condition. The steel potential (phi) at a distance (z) under disbondment from the holiday can be estimated by: (phi-E(OCP)):(phi(0)-E(OCP))=e(exp-C(1). All variables in this equation can be measured or estimated. The crevice corrosion rate can be computed from the Tafel equation.


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    Titel :

    Reassessment interval estimate based on corrosion rate under a delaminated coating with O2, with or without CP


    Weitere Titelangaben:

    Berechnung des Wiederbewertungsintervalls basierend auf der Korrosionsgeschwindigkeit unter einer abgelösten Beschichtung mit O2, mit oder ohne kathodischen Korrosionsschutz


    Beteiligte:
    Song, F.M. (Autor:in) / Sridhar, N. (Autor:in)

    Erschienen in:

    Corrosion 2006, 61 ; 06186/0-06186/18


    Erscheinungsdatum :

    2006


    Format / Umfang :

    1 Seite, 15 Bilder, 1 Tabelle, 7 Quellen


    Anmerkungen:

    1-18


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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