Marine Corrosion & Cathodic Protection

Today  much of our infrastructure built upon steel  components is seriously threatened by a destructive and persistent enemy: Corrosion.
This  undesirable process is initiated  by the  formation of  corrosion  cell  which  has  three essential  components : an  anode  and  a  cathode  coupled  in  an electrically conductive  solution  ( electrolyte).The  corrosion  of bare  steel occurs  by an electrolytic  mechanism  requiring  the  presence  of  water  and  oxygen. The  overall  reaction  may  be  expressed as : 4 Fe + 3O2 + 2H2O →2 FeO3  H2O  (rust).
This is the  result  of  two  separate  reactions , one taking place at  anodic areas and  producing electrons , another at  cathodic areas and  consuming electrons.

Anode 4Fe → 4 Fe++ + 8e
Cathode  2O2  + 4 H2O  + 8e → 8OH

The  ferrous  and  hydroxyl  ions  produced  by  these reactions then  react  to  form  ferrous  hydroxide , which  in  the  presence  of  oxygen  is  oxidized  to  hydrated ferric  oxide  , or  rust.

4 Fe ++  + 8 OH → 4 Fe ( OH) 2
4 Fe (OH2) + O2 → 2Fe2O3  H2O  + 2 H2O

Accordingly  in  the  rusting of iron there is a flow  of  electrons in the metal from  the  anodic to the cathodic  areas  and  a corresponding corrosion current in the  electrolyte carried  by the  movement of ions in solution. It has been demonstrated  that the amount of current that is flowing  is  equivalent  to  the amount of metal corroded, in  accordance  with Faraday’s law. Corrosion  always develops at the anode where current  leaves the  metal  and  enters the  electrolyte , whilst a protective  effect occurs at  the cathode. Thus  if  the  whole  metal made sufficiently  cathodic , corrosion will not  occur.
This  is the  basic principle of cathodic protection – the  practice of  using electrochemical  reactions to prevent  the  corrosion  of steel  structures.
The essential  factor  in cathodic  protection  is  to  ensure that the unwanted anodic  reactions  are  suppressed  by  the  application  of an opposing  current.
This opposing current can be  achieved by either of two techniques:

1.    Sacrificial Anodes – By corroding away a more reactive metal.
Anodes based  on  alloys of  Zinc , Aluminum and  occasionally  Magnesium are  attached to the structure  and  corrode in preference to  the  protected metal. Consequently  these  anodes  require  renewal  at routine intervals.

2.  Impressed  Current – A protective  current  is impressed  on  the  structure through  semi-inert anodes.

THE COMPANY

ZBA-CATHODIC PROTECTION SERVICES is a privately owned company established in 1980 by mr Zymaris Vasilios. From date of inception to present the company has been involved in the manufacturing of sacrificial anodes ( Zinc, Aluminum, Magnesium ) for shipping offshore and industrial applications. Since the late 80's ZBA focused in providing innovating cathodic services in marine market.

The company's involvement in corrosion control spans all aspects of the marine sector including anodes for leisure boat market to commercial deep sea shipping and shoreline structures such as piling, jetties, lock and dock gates, pontoon systems.

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GET IN TOUCH

Phone 1: +30 210 4612413

Phone 2: +30 210 4620977

Fax: +30 210 4616859

Email: info @anodia.gr 

Address: Head Office: 46, Akti Kondili Str., Piraeus

Facilities: 27 Km Palea Ethniki Odo Athina-Thiva, Mandra Attikis Tel.: +30 210 5557542 FAX.: +30 210 5557839

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