Mathematical models for cathodic protection of an underground pipeline with coating holidays. Part 1: Theoretical development

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Corrosion

DOI:https://doi.org/10.5006/1.3280467· OSTI ID:477468

Orazem, M E; Esteban, J M ^[1]; Kennelley, K J ^[2]; Degerstedt, R M ^[3]

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1. Univ. of Florida, Gainesville, FL (United States). Dept. of Chemical Engineering
2. ARCO Exploration and Production Technology, Plano, TX (United States)
3. Alyeska Pipeline, Anchorage, AK (United States)

Mathematical models were developed to predict cathodic protection (CP) requirements for coated pipelines protected by parallel anodes. This work was motivated by the need to estimate current and potential distribution on a pipe when anodes are placed nearby or when discrete coating holidays expose bare steel. The mathematical model solves Laplace`s equation for potential with boundary conditions appropriate for the pipe being protected, the anode, and any region through which current does not pass. The current density on bare steel was assumed to be composed of contributions from corrosion, reduction of dissolved oxygen, and evolution of hydrogen. Kinetic parameters were obtained from independent experiments. The anode was assumed to have a constant potential, and current was allowed to flow through the coating under the assumption that the coating is a high-resistance ionic conductor. A boundary element technique coupled with Newton-Raphson iteration was sued to solve the governing equations for two-dimensional (2-D) and three-dimensional (3-D) configurations. Results showed good agreement with experimental values and can be used to assess viability of CP designs.

• Sponsoring Organization: USDOE
• OSTI ID: 477468
• Journal Information: Corrosion, Journal Name: Corrosion Journal Issue: 4 Vol. 53; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
36 MATERIALS SCIENCE
CATHODIC PROTECTION
DEFECTS
DESIGN
EQUIPMENT PROTECTION DEVICES
MATHEMATICAL MODELS
PIPELINES
PROTECTIVE COATINGS