Types of AF anodes

Cathelco has developed a range of anodes with mountings which enable them to be installed in the seachests or strainers of almost any type of vessel.

The size of the anodes is determined by the flow rates and their anticipated design life, taking into consideration the scheduled dry docking period.

Detailed drawings are supplied for every ship to assist in installation and ensure that the anodes are positioned for maximum effectiveness in the seawater flow.

The anodes can be installed using a number of mounting arrangements including steel flanges, steel sleeves, nylon mountings and cofferdams.

  • Steel pipework – protected by copper and aluminium anodes.
  • Cupro-nickel pipework – protected by copper and ferrous anodes.
  • Anodes with integral cathodes – used where there is no return path for the current in close proximity. Nano and Omni anodes are examples.
  • Seachest mounted anodes – generally installed at newbuilding and are replaced at drydocking.
  • Strainer mounted anodes – can be replaced at any time when the vessel is alongside.
  • Anodes with dedicated cathode arrangements. Used where strainer bodies are internally lined and the strainer basket is isolated.

 

Copper anodes 

These are used in the majority of installations to protect steel pipework against bio-fouling through the creation of copper ions. Standard sizes range from 60mm to 120mm in diameter and 100mm to over 1,000mm length. The photograph shows the anode fitted with a flange mounting arrangement.


Aluminium anodes  

The purpose of aluminium anodes is to assist in anti-fouling process through the production of aluminium hydroxides when protecting steel pipework. They also produce a cupro-aluminium film which acts as an anti-corrosive layer on the internal surfaces of pipes. The anode is shown with a weld-in mounted sleeve.
 


Dual purpose anodes

In cases where there is a requirement for anti-fouling and corrosion suppression, but only space to fit one anode in a strainer, this dual purpose design provides an effective solution. Dual purpose anodes can be produced with either copper/aluminium or copper/ferrous in a single assembly. It is shown here with a nylon mounting which simplifies installation.


Ferrous anodes

These are used to protect cupro-nickel pipework which is commonly found on naval vessels. By producing ferrous ions, the ‘soft iron’ anode helps to maintain a protective oxide layer on the internal surfaces of pipes to suppress corrosion. The anode is shown with a cofferdam arrangement.


Stub length anode with steel sleeve

These anodes are used on vessels such as patrol craft, tugs and fishing vessels which have small seachests with relatively low sea water flows.


Stub length anode with plastic sleeve

This anode is designed for use in a strainer and has a plastic sleeve. It can be used in strainers made from any material such as cast iron or copper nickel.


Omni anodes

Small and versatile, Omni anodes have been developed for fitting in the smaller types of seachests and strainers found on workboats and luxury yachts. Designed with integral cathodes, they can be fitted in plastic strainers, pipes and areas where a suitable cathode does not exist.


Nano anodes

These miniaturised anodes have been developed for installation in the strainers of luxury yachts and work boats. Their compact design means they can be used in a wide range of applications.


Pico anodes

As the smallest in the Cathelco range, Pico anodes can be fitted in 3” diameter pipes on yachts and workboats. They provide a ‘trace’ of copper which is sufficient to prevent bio-fouling in small pipework systems.


Cathodes

In some cases, when using standard anodes, it may be beneficial to have a dedicated cathode to avoid any problems resulting from stray current corrosion. This particularly applies where strainer bodies are internally lined and the metallic strainer basket is isolated. It is also advisable in situations where seachests are well painted and do not contain sacrificial anodes or where there is the need to avoid any interference with impressed current cathodic protection systems (ICCP). The cathode can be either isolated (dedicated) or connect to the ship’s earth.