Coke Column Guidelines for Deep Anode Systems

OH NO, My Anode Bed is Not Performing!

This article explores a deep anode system gone wrong and guidelines for properly sizing the system coke column.


Earlier this year, we received a call from a pipeline customer with whom we have a solid relationship.

Historically, they used graphite anodes for their deep anode installations. But over the past few years, they began trying the MATCOR Durammo® Deep anode System with success.

When one of their new Durammo anode installations started having strange operating data, it was time to get MATCOR on the phone pronto and figure things out.

MATCOR reviewed the RMU operating data on the wayward installation and found that the data was indeed strange.

The DC output oscillated from periods of robust DC current output to periods of no discernible DC output. We also looked at the deep anode system design and noted the rather short coke column height. The height was only 100 ft of active anode in an 8-inch column. We sent a technician to the site to investigate.

First, we checked the installation and operation of the remote monitoring unit (RMU). Was a poor RMU connection causing intermittent good/bad data? This was not the case.

Next, we checked the continuity of the two anode lead cables. The Durammo® system has a top lead cable and a bottom lead cable. These two cables should be electrically continuous. In this installation, they checked out properly.

Finally, we checked the vent pipe for obvious issues.

Having confirmed that the spurious data was not the result of a poor RMU connection and that the anode system cabling appeared to be intact, we began to suspect that the problem was in the coke column and its immediate environment.

The Culprit? A Small Coke Column.

When we investigated further, we determined that the on-again, off-again readings could be the result of excessive gas generation into a rather small coke column. Both phenomena are heavily impacted by the anode system’s coke column to earth current density.

When the anode system generates more gas than can be exhausted through the vent pipe and diffused through the surrounding earth, gas molecules begin to accumulate between the column particles and at the anode to coke and coke column to earth interfaces. Gas is not electrically conductive, and with enough trapped gas in the column, the system resistance can quickly rise to a point that the anode system cannot overcome this resistance, and the current output drops quickly.

A short-term solution is to turn off the anode system for a period, allowing the gas to disperse inside the coke column and the system should return to normal operation. At least until the gas molecules build up again to block the anode system.

Coke Column to Earth Interface Current Density: The Magic Number

The magic number often cited for anode coke column to earth interface current density is 150mA/ft2. Anything above this number might cause problems. Below this number, history shows that the impact of gas blockage and drying out are generally minimal.

In our example, a 100 ft coke column with an 8-inch diameter hole means that any current output above 31 amps would be pushing that 150mA/f2 threshold.

The 150mA/ft2 current density assumes a high-quality, properly installed coke. This forms a well-compacted column that promotes electronic conduction and limits electrolytic conduction. A well-formed coke column is critical for anode systems using mixed metal oxide anodes, since MMO anodes have an inherently smaller surface area available to be in contact with the column.

It is unclear why the cp system designer recommended a short anode active length for this anode system – other than perhaps the cost saving of using less coke backfill.

While a shorter column does have a positive cost impact, the performance can become an issue, as was the case with this installation. Ultimately, this customer is planning a new Durammo® anode installation for this location with a significantly longer active area.


Need information or a quote for MATCOR deep anode systems? Please contact us at the link below.

MATCOR Successfully Completes Tank CP Project In Mexico

JA Electronics explosion-proof rectifiers for tank CP project in Mexico.

MATCOR recently completed a significant tank CP project in the Mexican port city of Altamira along the Gulf of Mexico. The project consisted of design, detailed engineering, supplying materials, providing installation supervision, and commissioning and testing the systems upon completion of the installation for nine above-ground storage tanks.

Tank CP Project Utilizes Linear Anodes

The cathodic protection system utilized MATCOR’s SPL Linear Anode Concentric Ring tank system that consists of individual, factory assembled, and tested anode segments. This approach facilitates a simple installation that does not require cutting, splicing, or joining anode assemblies in the field. The anode rings utilize a redundant anode cable feed system that assures reliability. This cost-effective solution protects the bottom of tanks on projects across the United States and around the globe.

Explosion Proof Rectifiers

MATCOR also supplied customized explosion-proof oil-cooled rectifiers (pictured above) for each of these tanks from our sister company, JA Electronics. These rectifiers are used in Class 1 Div 2 hazardous areas. Additionally, cast aluminum Class 1 Div 2 junction boxes were also manufactured and supplied by JA Electronics.


Click below to get a quote for your tank CP project, or learn more about MATCOR’s cathodic protection solutions.

Training the Next Generation of Corrosion Technicians

MATCOR hiring corrosion technicians; entry level cathodic protection jobs.

Entry Level Cathodic Protection Technician Opportunities

The Cathodic Protection industry is a great niche that offers entry-level opportunities with tremendous long-term advancement potential. Unfortunately, we do not have enough Cathodic Protection technicians for the short, medium, and long term.

It’s not a sexy industry, but it has great-paying jobs located in the US. Once you are trained and have a few good years of experience, entry level cathodic protection jobs enable you to pick where you want to live, enjoy tremendous job security, and gain new opportunities.

A growing regulatory environment, aging pipelines that require more frequent monitoring and servicing, aging of the existing CP technician workforce, and decades of failing to attract new people in sufficient numbers has led to a significant shortage of CP technicians.

The Great Resignation

You have probably heard about the Great Resignation, an ongoing economic trend in which employees are resigning from their jobs. According to a recent Times article, Ryan Roslansky, the current CEO of LinkedIn, defined this differently as the Great Reshuffle. We have seen a 54% increase in the number of people changing their job descriptions. For Gen Z, that increase is 80%.

The bottom line is that workers, especially younger generations, are quick to change jobs as they attempt to find their interests in the world. These changes are occurring in the high-paying technical and industrial jobs as well.

Looking for a Great Opportunity?

So, if you are looking for your next job and hoping to find something that can lead to a meaningful career, look no further. MATCOR is always looking for eager young men and women who have an aptitude for hands-on mechanical work and sound math and science skills to fill entry level cathodic protection jobs.

Travel and Training!

Early in your career, you can expect regular travel as you gain more experience – about 75% of the time. We will also provide the requisite training. Many of our technicians advanced within MATCOR or took an opportunity elsewhere to work for pipeline companies as area technicians where the travel requirements are significantly less.


If you are interested in a challenging, rewarding career in an industry where the opportunities are endless, please contact MATCOR. We are hiring! Learn more about MATCOR careers or click below to apply for open positions.

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