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Modeling of potential distribution of subsea pipeline under cathodic protection by finite element method
Author(s) -
Marcassoli P.,
Bonetti A.,
Lazzari L.,
Ormellese M.
Publication year - 2015
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201407738
Subject(s) - subsea , cathodic protection , finite element method , galvanic anode , coating , anode , materials science , electric field , electric potential , galvanic cell , potential gradient , mechanics , marine engineering , engineering , structural engineering , composite material , electrical engineering , metallurgy , voltage , physics , electrode , quantum mechanics
This paper deals with the evaluation of the subsea pipeline integrity through the combination of potential profile, electric field gradient, and the modeling of the electric field originated by bracelet galvanic anodes by finite element method (FEM). The potential profile as well as the electric field gradient measured during a survey provide the representation of the cathodic protection (CP) level and the location of anodes and coating defects. Nevertheless, by overlapping the electric field calculated by a dedicated FEM modeling, a more accurate interpretation is achieved in order to estimate the critical coating defect size and to evaluate the effect of the presence of multiple defects. FEM modeling was based on a simplified 2D domain reproducing the main geometrical, physical, and electrochemical parameters, such as sea depth, mud burial depth, seawater and mud resistivity, current density and potential distribution. Boundary conditions were defined by assuming constant potential at galvanic anode, electrical insulation of the coating and by considering Butler–Volmer equation for steel surface at coating defects. Coating defect size, sea depth, mud burial depth were considered in a generalized parametric equation. An example of the application of the model is shown on the basis of results obtained by an inspection campaign.