Cathodic Protection Services
Normally used in conjunction with coating systems, cathodic protection is a dynamic preventative measure, that can stop or reduce the rate of corrosion in aggressive soil or electrolyte conditions.
Electrochemical in nature, cathodic protection is used to prevent corrosion on buried or submerged metallic structures such as pipelines, storage tanks and offshore structures.
Since 1950, Corrosion Service Company Limited has been at the forefront of advancing the science of cathodic protection, and today ranks as one of North Americas leading specialist corrosion prevention companies. With highly trained engineers and technicians certified at various levels by the National Association of Corrosion Engineers International and located across North America, Corrosion Service can design, supply, install and maintain any type of cathodic protection system. Please select from the categories below, to learn how Corrosion Service is able to ensure the longevity of your assets.
The Corrosion Service Technical Library that Documents our Past and Defines our Future
Since our founding Corrosion Service has and remains a leader in the corrosion control industry, supporting the various industries in North American and around the World, ensuring asset integrity by providing responsible engineering services. As part of our continued commitment we would like to welcome you to our electronic Library as the place to view our various technical paper written and presented over the past 69+ years that have supported the corrosion industry advancement.
We also converted a prime corner office into a Library at our Head Office and dedicated the room to Sorin Segal for his commitment to Corrosion Service, the numerous papers presented, the engineering mentoring within Corrosion Service and to our industry. We would be pleased for you to come and view this comprehensive library that includes various text books, relevant publications, all NACE Materials Performance magazines presented since first publication, technical bulletins and various other related corrosion related print material.
The History of Cathodic Protection
London 1824, cathodic protection was first described by Sir Humphry Davy in a series of papers presented to the Royal Society. In the same year the first application of cathodic protection was to attach sacrificial anodes to the ship HMS Samarang. The anodes were made from iron and each were attached directly to the hull clad copper sheath below the waterline and it was successful in dramatically reduced the corrosion rate of the copper. Due the cathodic protection reaction of passivation at the cathode, the side effect of was the increase in marine growth on the copper cathode. Usually, copper when corroding releases copper ions which have an anti-fouling effect. Since excess marine growth affected the performance of the ship, the Royal Navy decided that it was better to allow the copper to corrode and have the benefit of reduced marine growth, so the application of cathodic protection was discontinued.
Davy was assisted in his experiments by his pupil Michael Faraday, who continued his research after Davy’s death. In 1834, Faraday discovered the quantitative connection between corrosion weight loss and electric current and thus laid the foundation for the future application of cathodic protection.
Thomas Edison experimented with impressed current cathodic protection on ships in 1890, but was unsuccessful due to the lack of a suitable current source and anode materials. It would be 100 years after Davy’s experiment before cathodic protection was used widely on oil pipelines in the North America and cathodic protection was applied to steel gas pipelines beginning in 1928 and more widely in the 1930s.
Cathodic Protection System Types - Galvanic/Sacrificial Anode
These Systems are based on a galvanic/sacrificial anode, a piece of a more electrochemically “active” metal, attached to the metal surface to be protected from corrosion when it is exposed to an electrolyte. These anodes are selected because they have a voltage (more negative electrode potential) than the metal of the target structure (typically steel). These systems do not require a Power source or controller and are self regulating and require very little maintenance.
Polarization of the target structure is caused by the electron flow from the anode to the cathode, through direct metallic contact either by bolting the anode to the structure or attaching a wire cable between the two metals. The driving force for the cathodic protection current is the difference in electrode potential between the anode and the cathode. During the initial phase of polarization, high initial current is required to move the to be protected structure more negative. Over time the galvanic anode continues to corrode, consuming the anode material until eventually it must be replaced. Galvanic or sacrificial anodes are specially alloys made in various shapes and sizes of zinc, magnesium and aluminium. For galvanic cathodic protection to work, the anode must possess a lower (that is, more negative) electrode potential than that of the cathode (the target structure to be protected).
Cathodic Protection System Types - Impressed Current Systems (ICCP)
These systems are powered by a DC electric current source and is used to drive the protective electrochemical reaction.
The system consists of discrete anodes connected to a DC power source, often a transformer-rectifier connected to AC power. In the absence of an AC supply, alternative power sources such as solar panels, water wheels, wind power or gas powered thermoelectric generators have been used successfully.
Anodes for ICCP systems are available in a variety of compositions, shapes and sizes. Common anodes are tubular and solid rod shapes or continuous ribbons of various materials. These include high silicon cast iron, graphite, mixed metal oxide, platinum cladding and basic materials like steel.
For land-based assets like pipelines, watermains, etc, anodes are arranged in groundbeds either distributed or in a deep vertical hole depending on several design and field condition factors, including current distribution requirements and land space availably. For water based assets like docks, pilings, etc., the anodes are secured to the sea floor, suspended from pilings or secured to support structure.
Cathodic protection transformer-rectifier units (TRU) or rectifiers come in standard offerings proving basic transformer diode rectification, AC to DC conversion and as well custom offerings where the wave form is chopped providing high efficiency capabilities. A variety of additional features, including remote monitoring, remote control, digital displays, integral GPS synchronous current interrupters and various type of electrical enclosures to house the components based on the environment to be located. The output DC negative terminal can range from one to many and are connected to the structure to be protected by the cathodic protection system. The pipeline rectifier DC positive output terminals can also consist of one or multiple dependant on the design requirements and are connected the anodes. The AC power cable is connected to the pipeline rectifier input power feed terminals.
Cars and Cathodic Protection
We are commonly asked about the commercially available devices sold to provide cathodic protection for cars. Harry Webster took it upon himself to publish the article Cars and Corrosion in NACE Materials Performance to assist the public on this topic and please feel free to review. In 1996 the FTC ordered David McCready, a person that sold devices claiming to protect cars from corrosion, to pay restitution and banned the names “Rust Buster” and “Rust Evader”.
To our Knowledge, there is no peer reviewed scientific testing and validation supporting the effective use of the devices.
Since our founding in 1950, we have built an extensive portfolio of specialist products for the corrosion prevention industry.
Our materials supply team has access to a full-range of Cathodic Protection materials both manufactured in-house and sourced from partner suppliers. Our dedicated supply chain team is based in Toronto alongside our material distribution hub, which is capable of delivering materials throughout the world on short notice.