CATHODIC PROTECTION

Cathodic Protection is a method to protect the steel pile wall of a jetty for corrosion. The Cathodic Protection on the steel piles works in the water (electrolyte) and will only be active from the area below the splash zone and the bottom of the Splash zone jacket till in the seabed.

The protection of the area covered on the steel pile in the seabed depends on the method of the Cathodic Protection.

Advanced-Cathodic-Protection-Steel-Jetty-Piles 

There are in principle two methods for Cathodic protection on the jetty piles, e.g.Sacrificial Anodes and Impressed Current. Impressed Current covers the whole length of the pile in the seabed as the Sacrificial method has a limited reach.  

 

I - Sacrificial Anodes Cathodic Protection

With the Sacrificial Anodes method an anode is welded on every pile, mostly a Aluminum or a Zinc anode. This Cathodic Protection method is working for every pile independently and has no effect on the other piles in the area. The anode material corrodes under the influence of the steel, and eventually it must be replaced.

It has to be taken into consideration that the protective current is only working until ± 5 meters in the seabed. For larger structures, like jetties, the economical border between an installation - protected by means of sacrificial anodes or impressed current - is approx. 10 years. If a protective period of more than 10 years is required, in general impressed current systems are more economical.

Note: The protection only covers the (out) side wall of the steel piles on which the anode is attached. For the corrosion protection of the inside steel wall we offer other solutions. Read more about Internal Corrosion protection on Jetty Piles  ....

CP-Sacrificial-Anodes-Steel-Jetty-Piles 

 

In the pictures below are samples of heavy weight aluminum anode which was "fallen" from a pile and recovered from the seabed.

Anodes-AL-400 

Within Indonesia there are two additional disadvantages when using Sacrificial Anodes. It is very difficult to control the well-functioning of such a system. You need qualified staff and divers to do regular maintenance checks. Next to that especially aluminum anodes are a commodity which are largely in demand. Therefore, jetty owners are often faced with an illegal change of ownership, which is not immediately noticed.

 

II - Impressed Current Cathodic Protection (ICCP)

For larger structures, like most Jetties, Sacrificial Anodes cannot economicallydeliver enough current to provide complete protection.

With the Impressed Current Cathodic Protection (ICCP) method a TRU(Transformation Rectifier Unit) is installed and connected with cables to the "bounded" piles (-) and to an external anode (+). With this method all the jetty piles in the area needs to be bounded with each other. The bonding takes care that all jetty piles of the structure are connected and form one electrical unit. A limited number of anodes can be placed on piles or placed on the seabed. However, we prefer wherever possible to bury anodes onshore. This prevents that parts of this ICCP system are illegally removed from the system.

As an ICCP system is in general designed for a theoretical lifetime of 25 years, only simple maintenance is required. The owner can easily check on a day-to-day basis whether the system is working without any heavy inspection. 

The placement of onshore anode beds in Indonesia has proven that it is the most reliable system.

If installed incorrectly a pile or a group of piles could become an anode by itself and could lead to an even faster corrosion process of these piles.

Note: The protection only covers the (out) side wall of the steel piles. For the corrosion protection of the inside steel wall we offer other solutions. Read more about Internal Corrosion protection on Jetty Piles  ....

CP-Impressed-Current-Steel-Jetty-Piles 

 

The pictures below shows a TRU (Transformation Rectifier Units). From this central unit the power supply to the jetty is provided and controlled.

  TRU

 

Survey on existing Jetties

For existing jetty piles we can conduct a survey – at cost - by our experienced engineers to do a comprehensive analysis of the installation at your site and advise you what needs to be done to extend the lifetime of the jetty piles in case the current protection is not adequate. Read more about Survey on Jetties  .....

 

More Information

We shall be pleased to explain more in detail about our anti-corrosion products and services, as well as to work together with you to find appropriate and cost effective solutions for your or your customers’ anti-corrosion problems and issues.

To be able to make an assessment of the current status and a preliminary proposal for Advanced Cathodic Protection System of your Jetty piling we will need at least the following information:

  • Type of piling
  • Number and length of piling
  • Depth of piling above and below seabed
  • Type & Specification of pile coating
  • Method of bounding of piling
  • Existing Cathodic Protection Systems in use
  • Power supply type and availability
  • Facilities for isolation from nearby structures
  • Classified hazardous areas
  • Layout drawings of the jetty and piling

 




Choose your Topic of Interest:

Corrosion Prevention on Jetties
Imbema Pacific Indonesia Solutions

1.Splash Zone ProtectionProject example
2.Cathodic ProtectionProject example
3.Internal CorrosionProject example
4.Pile Cap ProtectionExamples of unprotected jetty piles