Improving cathodic protection

In the foothills of the Andes, among the sprawling vineyards of picturesque Mendoza, Argentina, stands an innocuous equipment cabinet located by the side of an infrequently used mountain pass. The cabinet’s superficial surface rust belies its importance as one of the most significant technological developments in modern day corrosion prevention.

The cubicle, battered from years of shot blasting by an abrasive cocktail of arid Patagonian winds and coarse earth, hides the cradle of a revolutionary approach to cathodic protection. The equipment within the cabinet resulted in an entirely new range of products that was the brainchild of two visionaries – Federico Meyer of AMETEK Solidstate Controls Inc. and Norberto Pesce of Omnitronic S.A.

Both Federico and Norberto became allies following a chance meeting some twenty-plus years ago. Federico a talented power electronics engineer, and Norberto, a fledgling corrosion engineer and entrepreneur, happened to exchange ideas. Norberto had identified how technically crude approaches to cathodic protection were at that time.

Engineering resources, he believed, were so extensively utilized in corrosion prevention to the point where questionable economics severely impeded the viability of many hydrocarbon processing and transport facilities.

Both men resolved to apply to cathodic protection many of the new technologies they had learned during their formative years as students and businessmen. Federico was especially keen on a new technology at the time – switch-mode power control; while Norberto, who in addition to being a NACE-certified cathodic protection professional, had a more than passing understanding of communications and monitoring applications.

The partners approached an Argentinean company, Perez Company, with their idea, and it became a participant in developing their solution for cathodic protection. The result was a first article test system placed in the Piedras Coloradas oil field in the Mendoza region owned by Perez Company. At the time, switch-mode technology was considered somewhat complex and not fully understood. However, the application of sound fundamentals resulted in an incredibly stable, efficient, reliable and resilient solution.

That pilot system protected half a dozen well casings. The rectifier and deep ground bed system were located in the center of the field approximately equidistant to each of the producing boreholes. Now after 18 years, a recent visit to the facility witnessed the continuing silent, maintenance-free, corrosion protection of the facility. Although peak oil production from the field is now well in the past, it continues to modestly contribute to the country’s infrastructure. It is a testament to the solid application of sound engineering principles combined with new technologies that yielded incredible results.

Today, essentially two types of cathodic protection are used to protect steel and other structures from corrosion. The first employs the use of galvanic or sacrificial anodes in various shapes and alloys with a more negative electrochemical potential than the metal (typically steel) structure they are designed to protect. The sacrificial anodes corrode over time, sparing the remainder of the structure. The anodes have only a limited life. Once they are no longer capable of protection, the structure begins to corrode.

This method also is unable to provide complete protection for larger structures, such as pipelines. Those applications require impressed current cathodic protection system that includes a rectifier, which converts an alternating current power source to a direct current that is properly calibrated to provide the required protection. Since the power source is delivered to the anode and not generated by degradation of the anode, the power supply may be recalibrated to the anode to provide additional power, when needed (as long as the anode remains functional), and to provide optimal protection to the pipeline or other structures.

Evolving CP systems

Over time, advanced cathodic protection systems evolved from these early breakthroughs to more reliable switch-mode technology. Much was learned regarding lightning protection in different terrains and the affect of altitude and geographical dynamics, none of which had ever appeared in textbooks. Spurred on by their early success at Piedras Coloradas, Mssrs. Pesce and Meyer developed a Mark 2 system.

The second-generation rectifier system had many subtle refinements. Newer switch-mode-specific components had been introduced to the market that further enhanced the system’s already impressive product reliability and efficiency. The system also benefited from innovative application of environmental protection strategies. In addition, Omnitronic S.A. worked hard to design a remote monitoring and control system that would further revolutionize the use of corrosion engineering resources. The theory was that by leveraging new communications technologies, engineering personnel could spend more time analyzing data and prioritizing corrosion prevention in a pro-active mode rather than reacting to high consequence corrosion threats.

To do this, Omnitronic had to overcome the vast distances pipelines covered as well as their often remote location with little supporting infrastructure. With this in mind Norberto formed a strategic alliance with Orbcomm S.A., a low-earth orbit satellite communications provider. By integrating a data transport layer as part of the system and offering it in combination with Omnitronic’s analytical software, AMETEK’s power conversion solution was complete. The Mark 2 system was a resounding success. The system incorporated digital and analog control loops enabling highly accurate constant potential cathodic protection. This complemented new polymer pipeline coatings (such as fusion bonded epoxies), being developed at the time that were particularly susceptible to disbondment with excessive protective potentials.

What always has been paramount in CP design has been the need for the accuracy of automated potential control; and yet, many of the older manual systems in the field still rely on moving coil volt meter and ammeter indications. With the incorporation of digital controls, newer systems remove the possibility of parallax errors that occur when observing a needle on a meter from differing, non-perpendicular angles, thus compromising the calibration and tolerance of the indicating device. The resultant increased accuracy helps to deliver optimized energy conversion, maximizing the effectiveness of the corrosion control device.

The Mark 2 was deployed in significant numbers by the transport division of Repsol YPF in the late 1990s. In particular, 53 units were placed on their oil pipeline, which starts at the Lujan de Cuyo refinery in Mendoza and runs all the way through Montecristo (Cordoba), ending in San Lorenzo in Santa Fe province near Rosario, Argentina. The feedback from Repsol YPF was extremely encouraging, so both companies continued their evolution of their advanced cathodic protection system.

By 2000, Frederico Meyer’s firm was part of AMETEK Solidstate Controls, a recognized leader in uninterruptible power supplies and battery management systems. At that time, AMETEK released ACTS 2000, a revolutionary single module cathodic protection system, which incorporated the very latest in component technology as well as unique digital control loop topologies. At the same time, Omnitronic had significantly advanced their capabilities, incorporating internet-based structures and broadening systems connectivity from just satellite to include fiber optic, VHF/UHF radio, microwave, and cellular modem, among others.

Flexibility was the keyword. With the ability to remotely control as well as monitor the most remote locations, companies such as Repsol YPF, Petrobras Argentina, PEMEX, PDVSA, Oldelval, Camuzzi and BP saved significant operating costs. Once again, the new systems were successfully deployed and achieved the same level of reliability as their ancestor unit all of those years before in the foothills of the Andes.

Particularly attractive to users was the system’s ability to remotely initiate an instant-off test synchronized to a highly accurate GPS clock. This in itself was not new, but when integrated with switch-mode technology and advanced state-of-the-art communications capabilities, the end result was a radically different operating experience. With a technologically advanced, automated and intelligent network, engineers were no longer required to trek to remote locations to conduct field maintenance or analysis.

In addition, users had the ability to select and refine cathodic protection remotely on an a la carte basis. For instance, users were now able to alter operation mode between constant potential, voltage or current or altering set points, all from behind a desk without the deploying field resources. And, it goes without saying that all outputs are automatically self-regulating, thus removing the need to have engineers carry out potentially lethal tap-changing procedures leading to only an approximated protection potential, notwithstanding the significant threat to personal safety.

Driven by the economic advantages of remote control and monitoring and system automation, AMETEK developed the ACTS2002. It is a multi-module system that, while similar to its predecessors, also has the ability to protect multiple assets at one time while also providing controlling and monitoring services through a single communications conduit. These features significantly reduce the amount of initial capital required for cathodic protection systems in applications where multiple storage tanks, pipelines and well casings are co-located. However, because of the system modularity, power modules can be paralleled for higher power outputs.

Operators now have the benefit of a “one system fits all” solution. This leads to reduction of spares holding, easier engineer training and the benefits of reduced operating costs. At the same time, Omnitronic released their Servmail 2 web-based portal software, which provides a complement to the ACTS2002. This permits multiple personnel to monitor and securely control systems at one time. It also empowers operations and engineering users to be mobile while still connected to their cathodic protection network.

The open architecture of the Servmail 2 software system allows users to potentially integrate the cathodic protection systems into third-party software analysis asset management products, should they so wish. Omnitronic continues to integrate additional modules such as a powerful defect progression system that allows the network to report faults (however infrequent they are) and to expedite necessary rectification through to full network serviceability. These enhancements provide additional tools to underpin 100% asset integrity.

Safety also is at the forefront of advanced CP rectifier design. In recent years, due to the extended life of pipelines, older CP systems have become less relevant to the needs of the modern corrosion engineer. In addition, several trends have made owner/operators increasingly aware of the need to enhance safety through training, shielding and system interlocks. These include a number of high-profile cases of fatalities and injuries which resulted from exposure to potentially lethal voltages. Owners and operators have also become increasingly aware of the need for a safe working environment when troubleshooting or setting up of an increasingly archaic infrastructure.

Among the most significant recent advancements in advanced CP systems is the ability to digitally implement setup, control and monitoring parameters. The simple issue of creating a panel with push buttons rather than the older method of “hands-on” manual turning of potentiometers with live potentials provides for a much safer work environment. Physical error-proofing safety barriers and reducing the need to interact with equipment on-site greatly increases personnel safety as well as reducing client liability.

Future CP systems

Modern CP systems should not only be able to protect an asset or multiple assets, but also should provide a quantifiable return on investment. It should be a total systemic approach with supplemental communications conduits and analytical software that is easily accessible from mobile locations. The solution should increase resource flexibility and responsiveness to specific unplanned events. It should have the ability to turn data into information by answering such typical questions as: Where do we need to intervene? Or, how well is the system performing? By benchmarking against these common questions and integrating with geographical and meteorological data, significant overall savings can be realized. Owners and operators can also be pro-active and in control of corrosion rather than a slave to it effects and consequences.

Several decades have passed since implementation of the first hybrid switch-mode concept at the Piedras Coloradas oil field. However, from that simple idea of applying smarter technology in response to a client’s environmental and economic needs, a new approach to cathodic protection emerged. No longer is cathodic protection a necessary evil. Instead, it is now a sophisticated and powerful tool that can extend the life of a production, transportation or storage asset well beyond previous expectations and do so at a fraction of traditional costs. This makes new geologically challenging fields, such as those recently discovered in Brazil and elsewhere in Latin America, well placed opportunities for cathodic protection.