Category Archives: MarineTech

Five Commonly Asked Questions About Cathodic Protection

Cathodic Protection

Cathodic protection is an important step that every homeowner and business owner should take because it really does make a huge difference. Unfortunately, not many people are aware what cathodic protection even means or what it involves. Check out some of the most commonly asked questions about cathodic protection below:

 

 

1. What is Cathodic Protection?

Cathodic protection is a method used to help protect metals that are buried deep in the ground from corroding. This is done through either turning the corroding metal into a cathode by an impressed direct current or attaching the metal to a galvanic anode. When cathodic protection is performed well through an impressed current, there must be an external power source employed like solar or AC. This method is also generally applied to those metal units that have large surface areas like storage tanks and transmission pipelines. With galvanic cathodic protection, though, it is all self-powered. That means it is the simplest type of cathodic protection. It’s typically used on metal units found in a soils environment. However, this method can also be employed to those bigger structures found in sea water.

 

cathodic-protection

 

 

2. How Do We Know That the Cathodic Protection is Effective?

Cathodic protection has been employed for many years to protect underground pipelines, offshore oil platforms,antifouling, shaft grounding found in ship hulls and underground steel storage tanks. That’s because many of these units are exposed to marine environments that are full of ballast water that causes corrosion. With all these years of employing cathodic protection, it’s clear that it really does work to protect your units from corrosion.

 

How Cathodic Protection Works?

3. Is There Any Maintenance Required Once the Cathodic Protection System is in Place?

As soon as the cathodic protection system is installed, you’ll need to get routine maintenance performed on it. This is typically done yearly. That’s because there is always the possibility for something to go wrong over time. However, with this routine maintenance, you are ensuring for any problems to be caught early on. For those impressed current systems that are used, the maintenance involves a visual inspection of the unit and checks regularly after that. With all the new forms of technology, though, many individuals opt for remote monitoring systems. They feel this is a much more convenient way of having their systems maintained.

 

4. Does Cathodic Protection Involve a Lot of Electricity?

Many individuals are under the assumption that cathodic protection systems use up a lot of energy since they run continuously. Even though they are left on 24 hours a day, this is not the case. Actually, very little energy is used with your cathodic protection system. That’s because most cathodic protection systems only use between 100 and 1,000 watts of power. This makes having one of these systems much more affordable.

 

Professionals

Look for proper training and certifications for the installation.

 

5. Do Cathodic Protection Systems Have to be Installed by Professionals?

While there is always the option to install your own cathodic protection system, this can be extremely risky. Unless you have the proper training and certifications, installation and maintenance of your system should be left to the experts.

The Role of Anodes in Deepwater Cathodic Protection

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Simply put, corrosion is defined as the process or action of corrosive chemical behaviour, which is a progressive modifi-cation or deterioration due marine growth prevention system, antifouling system, copper anodes
to chemical oxidation.

When it comes to certain job responsibilities and daily tasks many people associate the process of corrosion to the wasting away or rusting of a pipe that’s buried beneath the ground. And so, corrosion can be thought of as the way natural forces continuously try to restore the developed works of humans to revert back to their original state of natural symmetry. Therefore, when it comes to a buried pipe, the process of corrosion is the earth and surrounding natural elements simply trying to restore the existing iron within the steel pipe to its original constant form of native iron ore or iron oxide.

The kind of corrosion that most people are familiar with and the kind that causes the most amount of damage to a buried pipe is known as electrochemical corrosion. This type is also commonly referred to as galvanic corrosion and sometimes known as electrolysis.

Using Anodes in Cathodic Protection

Sacrificial anodes’ are often used in cathodic protection systems. The anode consists of metal alloy containing a more active voltage than the structure’s metal it’s protecting, or the cathode. When it comes to potential, the difference between either metal indicates that the material of the sacrificial anode will corrode rather than the structure itself. This process successfully stops how the oxidation process reacts to the structure’s metal that’s being protected.

Also, there needs to be two other existing conditions in addition to the cathode and anode in order for the sacrificial anode process to work. Essentially, there needs to be a return existing path for the electrons to properly flow from the said anode to the targeted material it’s intended to protect (physical contact is the most common way) and an electrolyte (i.e. humidity or water) to transmit the electrons.

Sacrificial Anodes

Sacrificial anodes usually come in three different metals: zinc, aluminium, and magnesium. Of the three, magnesium contains the most negative electro-potential and is more appropriate for on-shore pipelines since electrolyte (water or soil) resistivity is considerably higher. However, if the difference in electro-potential is too much, the cathode (protected surface) can possibly become brittle or sometimes cause the coating to “disbond”.

Aluminium and zinc are typically used in salt water since the resistivity is usually lower. General uses include the hulls of boats and ships, in salt-water-cooled-down marine engines, inside the walls of storage tanks, on small boat rudders and propellers, and on offshore production platforms and pipelines.
The main benefits of using sacrificial anodes include the following:

• Easy to install
• No external power source required
• Overprotection is highly unlikely
• The low voltage and current that runs between the protected surface and the anode rarely produces stray current
• Monitoring and inspection is easy for trained staff

On the other hand, there are some disadvantages as well such as a restricted current capacity relative to the anode’s mass, ineffectiveness regarding high-resistivity environments, increased water and air flow on moving structures (i.e. ships), and more weight on the structure being protected as well. Find out more at www.cathodicme.com.