CEMAR PC – R&D Cathodic Protection


Electrochemical Marine Corrosion – Cathodic Protection

Recherche protection cathodique - Corrosion accélérée en milieu portuaireProgram

CEMAR-PC aims to improve the knowledge of the properties of steel/environment interfaces of structure in order to optimize the implementation and design of a cathodic protection system.

puce corrodysFinancial backers, coordinators, partners

CEMAR PC (Corrosion Electrochimique MARitime – Protection Cathodique) is a collaborative project within industrial partners (ArcelorMittal, BAC Corrosion Control, ACCOAST, A-CORROS), le CETMEF, Grands Ports Maritimes (Nantes-Saint-Nazaire, Le Havre, Marseille, Dunkerque) and Research Laboratories (LEMMA – University of La Rochelle and LISE – CNRS/UPR15, Corrosion Institute, Corrodys).

Arcelor MittalBAC protection cathodiqueACCOAST Corrosion portuaireA-CORROSCETMEF Recherche et développement en protection cathodique

Port de Nantes Saint-Nazaire

Port du HavrePort de MarseillePort de DunkerqueLEMMA Laboratoire d'Etudes des Matériaux en Milieux AgressifLISE Laboratoire Interfaces et Systèmes Electrochimiques Institut de la Corrosion

puce corrodysLe contexte

Phénomène de corrosion accélérée en milieu portuaire

Metallic infrastructures of port works, mainly sheet piling and retaining piles, are made of carbon steel. In the area of bass waters (upper part of the immersion, discovery zone only to strong tidal coefficients), these infrastructures are sometimes affected by a localized accelerated corrosion phenomenon whose mechanisms are not fully controlled.

schéma des vitesses de corrosion differentes en environnement portuaireIn order to combat this type of corrosion, the most used method in the port environment is the galvanic anode cathodic protection. The principle of this technique is to reduce the potential of the metal and thus reduce the rate of corrosion in electrolytic medium by establishing a galvanic coupling between the metal to protect work and anodes composed of a metallic material less noble than the structure.

Schema of variable speeds corrosion for the same structure. Click on the diagram to enlarge.

puce corrodysObjective

Industrial objective

  • Improve procedures for sizing and therefore the effectiveness of cathodic protection in sites subject to the tide.
  • Estimate the risks of corrosion associated with a rupture of the cathodic protection.
  • Write a manual of good practices of engineering on the protection against corrosion. Make available to managers of sea or river works, a practical manual advice for the implementation of protection against corrosion, suitable the structure to protect and its environment.

Scientific objective

  • Know the characteristics of the deposits which may form on the surface of steels in order to understand and anticipate the influence of these deposits on corrosion and protection processes.
  • Understand the influence of physico-chemical parameters, along the water column sites subject to the tide on the potential of corrosion and cathodic polarization.

puce corrodysResearch method

This research work is based on the analysis of the physico-chemical and electrochemical characteristics of deposits formed on coupons of steel exposed several years, under different conditions of protection in area of low water, on port sites.

Portique d'essais de protection cathodique en milieu portuaire - recherche protection cathodique

Analyses and measures realized

  • Physico-chemical measurements on the water column in continuous (temperature, dissolved oxygen, salinity, resistivity, pH, speed)
  • Analyses of the deposits: structural and elemental analysis by SEM / EDS, analysis in destructive layer by Micro-spectrometry Raman, powdered analysis of crystalline phases by x-ray Diffraction.

puce corrodysPictures

puce corrodysIssues raised by the R&D cathodic protection program

  • What are the main physico-chemical factors to take into consideration for the sizing study?
  • What is the electrochemical behavior of steel and anodes depending on their position along the water column, particularly on sites exposed to tides?
  • What are the possible risks of momentary break of cathodic protection (during the few months that may precede the anode replacement, or when the anode fall down)?

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