Category Archives: Marine

What is The Best Anode For Low Temperature Seawater Applications?

A MATCOR customer recently inquired about mixed metal oxide (MMO) anodes for low temperature seawater environments amid a concern over the formation of chlorine hydrates.  

This article describes a special low temperature MMO anode formulation that addresses these concerns. MATCOR is currently working on two projects that will potentially benefit from this modified MMO anode.

What is the best anode for low temperature seawater applications?
What is the best anode for low temperature seawater applications?

What concerns are there over the use of MMO anodes in cold water environments?

As a general rule, MMO anodes perform exceptionally well in chlorinating environments such as seawater.  Almost all MATCOR anodes are manufactured using a standard MMO coating formulation that is designed to operate efficiently in a wide range of electrolytes and environments.

In low temperature seawater, however, there is the possibility that high localized concentrations of chlorine can be formed in conjunction with a significantly reduced pH environment. 

Chlorine hydrate is a chlorine molecule caged in 8 molecules of water.  The generation of chlorine hydrate is strongly related to localized mass transport limitations which are greater at lower temperatures. There is no direct impact of chlorine hydrates to the titanium anode substrate or the anode coating. However, the presence of significant amounts of chlorine hydrate may result in inhomogeneous current distribution due to the differences in the conductivity. This could impact both the effectiveness of the current distribution being applied to the cathodically protected structure, and, over the long term, the wear rate or life of the coating.

Localized factors have a significant effect on the conditions that result in chloride hydrate formation. In addition, the properties of the MMO coating can have an impact.

MATCOR’s standard MMO formulation is suitable for low temperature chlorinated environments.

A modified formulation provides the best anode for low temperature seawater applications

By modifying the formulation, we can lower the oxygen overpotential to promote greater oxygen generation and less chlorine. This modified formulation reduces the quantity of chlorine gas while favoring the generation of oxygen.

This “cold” MMO formulation in low temperatures can be expected to reduce chlorine and boost oxygen generation by as much as 15%.

The other factor that has a large influence is current density, as it is this current density that determines the quantities of both oxygen and chlorine gas that are evolved. Reducing current density reduces the quantity of chlorine gas being generated.

In summary, MATCOR’s standard MMO coating formulation is a broad-based formulation that works in a wide range of electrolytes.

For areas of significant concern due to a combination of low temperature electrolyte and high current density, a special low temperature formulation is available. This formula reduces chlorine generation in favor of oxygen, helping to reduce any concerns over low temperature and chlorine hydrate formation.


If you have questions, or would like information on MATCOR’s special MMO anodes for low temperature applications, please contact us at the link below.

Contact a Corrosion Expert

Impressed Current Sled Anodes for Marine Structures – FAQs

Impressed current sled anodes to prevent corrosion of near shore marine structures such as docs, piers and jetties.
Impressed Current Sled Anode for Marine Structures

MATCOR is a leading manufacturer of impressed current sled anode systems and as such we tend to get asked a lot of questions about sled anodes.  Here are some frequently asked questions:

Does it matter whether sled anodes are to be installed in seawater, brackish water or freshwater?  What if the water salinity varies with the season or with tidal action?

These are two related questions, and both have to do with the conductivity (or resistivity which is merely the inverse of conductivity) of the water where the anodes will be located.  The conductivity of the water plays a critical role in determining the overall system resistance and current output of the system.  For freshwater locations, the relatively low water conductivity requires a significant quantity of anodes to keep the overall system resistance down.  In those instances, a sled anode may not be the best design option as sled anodes are most cost effective in brackish or saltwater environments. For environments where the conductivity can vary seasonally or with the tides, such as estuaries or tidal river boundaries, special consideration may be required such as constant current or auto-potential controlled power supplies.

Why would we use impressed current sled anodes as opposed to galvanic anodes? 

Depending on the application, there are compelling reasons for the use of each type of system. Galvanic anodes do not require an external power supply, are less subject to interference issues, and can be closely coupled directly to the structure. The impressed current sled anodes can greatly simplify installation, reduce overall costs, typically have a longer life, and can produce a lot more current from a lot fewer anodes. The choice of anode type is very much a site-specific consideration requiring a proper engineering evaluation during the design phase.

Are there any specific concerns with marine wildlife when evaluating cathodic protection systems?

Marine wildlife is generally unaffected by the presence of a cathodic protection system. Cathodic protection systems have been used in commercial aquariums and fish hatcheries without any impact on the marine life. At the structure, cathodic protection can result in a localized environment that reduces or inhibits the growth of barnacles while changes in the pH at the structure’s surface encourage the growth of calcareous deposits which reduce the current requirements and provide a form of protective coating for the steel structure.

The MATCOR sled anodes utilize a wooden base – are there any concerns with the deterioration of the wooden base releasing in chunks of wood that could damage intake structures?

We have not experienced any such problems – the wooden base is designed to sink into the mud along the sea floor and provide an anchor.  Wood holds up very well in this environment; however, over time the wood will slowly become food for cellulose processing bacteria and eventually will slowly be degraded. This process is a natural process and occurs over a long period of time.  There is no expectation that the wood base would break into pieces that could damage an intake structure. MATCOR can provide an inert non-metallic plastic base that would be like wood but not subject to natural biodegradation.

How do you protect the cabling from the Sled Anode back to the system rectifier?

MATCOR utilizes an HMWPE cable that has a very robust exterior jacket that is suitable for direct burial in soil or water environments. The cable is housed inside a 1” diameter flexible drilled PE pipe that provides mechanical protection for the cabling. We recommend the use of concrete weights to secure the cable along the seafloor. The drilled PE pipe holes facilitate the cabling sinking into the seafloor mud providing additional protection for the cabling.

What about dredging operations?

For locations that are subject to occasional periodic dredging operations every few years or so, MATCOR can provide a locator float and lifting lugs to allow for the anodes to be removed prior to dredging operations. If the frequency of the dredging operations is such that this would be a regular occurrence (multiple times per year), then consideration should be given to alternate designs that would not require anode removal on regular basis.


For information on MATCOR’s Sea-Bottom Marine Anode Sleds or for assistance with marine near shore cathodic protection system design, please contact us at the link below.

Contact a Corrosion Expert

6 Sled Anodes Replace 274 Galvanic Anodes for Marine Jetty Corrosion Protection

Marine environments can be some of the harshest environments on the planet for corrosion of steel structures. Indeed, the earliest application of cathodic protection can be traced back to Sir Humphrey Davy and the British Navy’s investigation into corrosion on copper sheathed wooden vessels. This video demonstrates MATCOR’s impressed current sled anodes that are successfully being used to protect steel piles for jetties, docks and other similar steel structures in marine environments.

At 1:03 in the video, we demonstrate how the marine anode sled operates with a trade show model.

Sled Anode
Sea-Bottom™ Anode Marine Sled Anode

At 4:05 you see a MATCOR Sea-Bottom Marine Anode Sled being lowered into the water as part of the cathodic protection system protecting a steel jetty structure in Indonesia. The jetty is constructed with four interior rows of concrete piles and an exterior row of 247 bare metallic piles. The operator initially considered galvanic anodes to protect the jetty from corrosion – until they compared the cost, time and effort to install the required 374 aluminum anodes each weighing 200 each. Instead they opted for six marine anode sleds, taking only three days to install.


For assistance with near shore marine anode systems, please CONTACT US.

Sled Anode Cable Connections

What is the best way to prevent damage to sled anode cable connections due to rough sea current and waves?

MATCOR marine sled anodes (Sea-Bottom™ Anodes) are designed with the cable connections routed inside a high density polyethylene (HDPE) protective pipe with holes to provide a level of mechanical protection. Then we use concrete weights to help secure the HDPE pipe (with the cable inside) to the sea bottom so that they are not subject to wave or tidal action.

Sled Anode Cable ProtectionThe protective housing is pictured here and called out as item 4 on the drawing on page 3 of our Sea-Bottom Marine Anode Sled brochure. For the concrete weights, you can use a variety of methods from sacks of concrete to custom formed concrete cast weights. Below is a photo of the weights that were locally supplied to us for a recent project in Indonesia. These weights are installed by divers during the sled anode installation.

sled anode concrete weights

For assistance with impressed current anode system design, MATCOR’s Sea-Bottom Marine Anode Sleds, project management or installation, please contact us at the link below.

Contact a Corrosion Expert

Impressed Current Anode Systems for Jetty Piling

One of the key decisions for any cathodic protection system design is the choice between an impressed current anode system or a galvanic (or sacrificial) anode system. This is especially true for marine applications where cathodic protection is commonly applied to structures such as steel piling systems on jetties and piers for corrosion protection. A recent MATCOR project highlights the choice between ICCP and Galvanic systems on a newly constructed jetty in Surabaya, Indonesia.

Impressed Current Anode Systems vs Galvanic Anode Systems

impressed current anode systems for jetty piling
Click on the image above to read the full case study comparing impressed current cathodic protection utilizing marine anode sleds with a galvanic anode system.

This case study article, which appeared in the October issue of Materials Performance includes a comparison of key factors for commonly used galvanic (aluminum) anodes and impressed current (titanium with mixed metal oxide) anodes. The key differences between an impressed current anode system and a galvanic anode systems include:

  • Anode consumption rates
  • Current density (CD) limits
  • Driving voltage
  • Anode quantities
  • Installation time and costs

The article describes these key differences in more detail.

Conceptual Design – Galvanic vs Impressed Current

Jetty applications can be designed using either galvanic anodes or impressed current anodes, and often it is a matter of client or designer preference. For this project in Indonesia, the cathodic protection designer reviewed both system types to determine the ideal design for this application based on a 30-year anode life. The final decision was based on several factors including total number of anodes and installation time required, in addition to safety considerations.

Impressed Current Anode System Installation and Commissioning

The final design called for the installation of six marine anode sleds, which took less than a week to complete.

For more details about this impressed current anode system solution for jetty piling cathodic protection, please read the full article in the October issue of Materials Performance. You can also access the full article HERE.

For assistance with impressed current anode system design, MATCOR’s Sea-Bottom Marine Anode Sleds, project management or installation, please contact us at the link below.

Contact a Corrosion Expert

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