All posts by MATCOR

Cathodic Protection Connections: Exothermic Welding vs Pin Brazing


Exothermic welding and pin brazing are two methods to connect a cathodic protection system to the protected steel structure. These connections route back to the rectifier to complete the circuit for an impressed current cathodic protection system. Or they connect to the anode lead cable in a galvanic anode system. They are an essential part of any cathodic protection system.

Exothermic welding and pin brazing cathodic protection connections resulted from historical needs in the railroad industry. In addition, both have a long history of use in the cathodic protection industry.

MATCOR has the experience and capability to use either connection technology depending on the client’s specifications or requirements. In the absence of a customer preference, MATCOR generally defaults to pin brazing for CP applications.

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Exothermic Welding for CP

The older of the two technologies is Exothermic or Thermite welding. More prevalent in United States specifications, this technology utilizes the heat generated from the reaction when you ignite a mixture of Aluminum powder and Iron Oxide III (ferric oxide Fe2O3). The resulting reaction is vigorously exothermic, generating temperatures more than 2000 C – sufficient to create molten iron.

Initially developed by German Chemist Hans Goldschmidt in 1893, exothermic welding connected steel rails on the Essen train line. In the 1930s, the technology gained widespread use for connecting bonding cables to railroad ties. This was thanks to the efforts of Charles Cadwell, a physicist for the Electric Railroad Improvement Corporation (ERICO.)

The Cadweld connection process has changed very little over time. It involves cleaning the structure surface down to the bare metal and laying the connector attached to the structure in a graphite mold. Next, you place an appropriately sized cartridge containing the aluminum powder and ferric oxide ready for igniting in the mold. Finally, using an ignitor sparks the reaction. As a result, an iron slug melts and flows over the copper conductor, welding it to the steel surface.

Cathodic Protection Connections: Exothermic Welding vs Pin Brazing

Pin Brazing for CP

Like exothermic welding, the railroad industry developed the second standard cable-to-structure technology—pin brazing.

In Sweden in the 1950s, high heat from thermite welding caused grain growth in the copper cable. As a result, connections to the rails were subject to fatigue failures from cyclical stresses associated with the movement of the rails as trains passed.

To solve this issue, the railroad industry developed lower-temperature joining technology using brazing. Brazing uses a range of silver-based filler metals to achieve the bond. These filler metals have a melting temperature between 620 and 970 C – well below the temperatures reached during exothermic welding.

Commonly specified in European standards, the pin brazing process has remained fundamentally the same since the 1950s, with some refinements to the equipment.

The pre-assembled welding pin and the pin brazing gun are the keys to pin brazing. The pin consists of a stud with a defined amount of flux encapsulated in the brazing metal. When you press the trigger, current flows through the pistol via the pin to the steel pipe. At the same time, an electromagnet is energized, drawing the pin holder and pin away from the steel surface, forming an electric arc. The arc heats the steel and starts to melt the tip of the pin. As a result, it causes the flux to melt and flow onto the steel. The electromagnet de-energizes when the current flow ceases, and the spring forces the molten stud onto the fluxed pipe surface. With the arcing stops, solidification is very rapid.

Comparing Exothermic Welding and Pin Brazing for Cathodic Protection Connections

Safety

Both methods are safe procedures when trained personnel follow the correct procedures. Neither method poses any environmental threat, although users should be sure to properly store and handle the thermite powder charges. For thermite welding, the process can be sensitive to moisture which could vaporize on contact with the molten iron slug. As a result, the potentially dangerous hot metal can be spat out of the mold. For this reason, you should conduct the pin-brazing process in damp environments and offshore applications.

Cathodic Protection Connection Reliability

Both connections have been used extensively and are widely accepted in cathodic protection. Unfortunately, no published data detailing the reliability of either connection technology exists, and reports of Cathodic Protection connection failures are infrequent and anecdotal. Lab testing on tensile load indicates that pin brazing is a slightly stronger bond; however, the loads at failure far exceeded any load possible in regular service. Nevertheless, both techniques will provide reliable, low-resistance connections when properly performed.

Metallurgical Effects

Both processes are thermal and will affect the metallurgical condition of the pipe. Many piping codes typically advise that the design consider the impact of any changes in the parent metal due to localized heating during the attachment process. Microhardness testing has shown that both connections are safe for the normal range of carbon steel pipe; however, some consideration must be given to thin-walled structures. Pin brazing results in lower temperatures and greater process control and should be considered for all thin-walled steel and alloyed piping.

Effects of Cathodic Protection Connections on Internal Coating and Fluids

Using thermal bonding to the exterior pipeline wall of a pipeline filled with highly flammable hydrocarbons requires some consideration. In addition, where internal coatings exist, it is reasonable to question whether or not thermite welding or pin brazing might damage the interior coating. Based on testing, the inner wall temperature rises more with thermite welding than with pin brazing; however, neither method’s results were sufficient to give any reason for concern.

If you need assistance with a cathodic protection assessment, please contact us. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

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[ARTICLE] Cathodic Protection Failure

Restore, replace, extend, or do nothing?

In the Autumn 2022 issue of Tanks and Terminals, MATCOR’s Ted Huck delves into four strategies you can take when your cathodic protection system is no longer working.


MATCOR provides industry-leading cathodic protection and AC mitigation solutions to tank and terminal operators around the globe.


If you need assistance with a cathodic protection assessment, please contact us. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

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AC Mitigation: 4 Approaches

AC mitigation is the process of designing and applying pipeline grounding systems to:

  • Prevent voltage spikes during fault conditions
  • Reduce AC current density to protect against AC-induced corrosion
  • Maintain AC step and touch potentials below 15 Vac to protect personnel from shock hazards

AC mitigation prevents voltage spikes and corrosion and protect workers

Pipelines that parallel overhead high-voltage AC transmission power systems are subject to AC interference. AC interference has several potential adverse impacts on the safety of personnel and pipeline integrity. Assuming that these conditions exist, there are several measures that can be taken to mitigate the AC interference present in a pipeline. These AC mitigation strategies are detailed in various international standards including two AMPP (formerly NACE) standard practices: SP0177-2014 Mitigation of Alternating Current and Lightning Effects on Metallic Structures and Corrosion Control Systems, which primarily focus on safety for operators and other people working on or near pipelines subject to AC current and lightning events, and SP21424-2018. This addresses the guidelines and procedures for risk assessment, mitigation, and monitoring of AC-induced corrosion on pipelines.

There are four basic approaches to mitigating AC Interference. These mitigation strategies are:

1. Fault Shielding

One of the primary concerns with high-voltage AC transmission systems parallel to buried pipelines is the risk that a fault condition at a transmission tower could result in the rapid discharge of fault current near the pipeline. This could lead to direct current arcing in soil – rare but very damaging. More common is the rapid ground potential rise that subjects the pipeline coating to large voltage gradients that result in coating damage. Fault shielding is a suitably designed grounding system that is installed between the tower footing and the pipeline that acts to shield the pipeline and shunt harmful currents away from the pipeline by providing a low resistance path to earth. This typically takes the form of a parallel shielding wire, either copper or zinc, connected to the pipeline.

2. Gradient Control Mats

When high levels of AC voltage are present on a pipeline, either during a fault condition or as the result of an inductive coupling during normal steady-state operations, personnel in close proximity to and/or touching any above ground or exposed appurtenance are at risk for electrical shock step or touch hazards. Installing a gradient control mat, which is a system of buried bare conductors, typically galvanized steel, copper, or zinc, connected to the structure, provides localized touch and step voltage protection by creating an equipotential area around the appurtenance.

3. Lumped Grounding Systems

Lumped pipeline grounding systems consist of shallow or deep localized grounding conductors that are connected to the structure at strategic locations to reduce the AC voltage level along the pipeline. This provides protection to the structure during steady-state or fault conditions from the nearby electric transmissions.

4. Gradient Control Wire

Gradient control wire grounding systems function the same as the lumped grounding system. With this type of system, long continuous grounding conductor(s) are installed horizontally and parallel to the pipeline. They are strategically located and sized to reduce the AC-induced voltage along the pipeline during steady-state or fault conditions from the nearby electric transmission.

For mitigating high levels of AC-induced voltage along a pipeline, gradient control wires are the most common form of AC mitigation. Hybrid systems that combine lumped grounding systems with gradient control wires are also common. Regardless of the type of pipeline grounding system used, all of these AC mitigation approaches involve installing a grounding device to the affected structure to allow AC-induced current and fault current to be quickly discharged off of the pipeline.

AC Modeling

Prior to installing an AC mitigation system, it is common to use complex AC modeling software to evaluate the impact of fault currents and estimate the steady state induced currents that can be expected along the pipeline. This information is used to determine the quantity and location of mitigation required based on numerous factors, including the resistivity of the soil, the physical characteristics of the pipeline, the operating parameters of the HVAC transmission system and the spatial distances between them.

Engineered AC Mitigation Systems

Based on a thorough assessment of the pipeline and high voltage AC transmission system interaction, including modeling results when available, an AC mitigation system is designed by experienced engineers familiar with the mitigation strategies detailed above. This engineered AC mitigation system would detail the quantity and location of grounding installations required for a specific application. MATCOR’s MITIGATOR is an example of this type of AC mitigation system.

Other features of an engineered AC Mitigation system include:

Special Backfill

It is quite common to install the grounding conductor in a special backfill material. The purpose of the backfill can vary depending on the conductor material chosen and the type of backfill used. The benefits of various types of AC mitigation backfill include:

  • Enhanced surface area – conductive backfills such as carbon or conductive concrete are used to effectively increase the surface area of the grounding conductor reducing the overall resistance to earth.
  • Corrosion/Passivation Protection – some backfills are designed to protect the grounding conductor from corrosion or passivation of the conductor that could adversely affect the life or impede the performance of the grounding conductor.
  • Hydroscopicity – some hygroscopic backfills readily attract and retain water from the environment, helping to maintain a low uniform resistance around the grounding conductor.

Solid State Decouplers

These devices are almost always used in conjunction with AC mitigation systems and are usually installed wherever the grounding system is connected to the pipeline. These devices are designed to allow AC current to flow off the pipeline during steady-state or fault conditions while blocking all DC current. This effectively isolates the pipeline’s cathodic protection (CP) system from the AC mitigation system, preventing the mitigation system’s grounding conductors from taking CP current from the pipeline.

AC and DC Coupons and Remote Monitoring Test Stations

Regardless of which mitigation strategies are being used, it is important to
design and install a monitoring system to be able to affirm compliance with the AC Mitigation criteria established in SP21424-2018. This includes monitoring both AC and DC current densities. The monitoring system should be designed to collect representative data at regular and continuous intervals.  This usually includes remote monitoring of AC corrosion criteria.

MATCOR provides complete AC Mitigation solutions including design, supply of materials, turnkey installations, and comprehensive testing services.


If you are looking for help with AC Mitigation systems or services, please contact us. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

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MATCOR Adds a New Drill Rig to Our Fleet

Drill rig for cathodic protection installation

MATCOR is excited to announce the acquisition of a new drill rig to our existing fleet of HDD and vertical drill rigs.

Our newest rig is designed to be a cost-effective option for drilling shallow holes. The rig features a much smaller footprint than the conventional deep anode drill rigs used for installing Durammo® and other deep anode systems.

Drill Rig Features

The smaller and more agile auger rig allows MATCOR to be able to maneuver the rig in tighter areas than the full-scale vertical rig would allow. Additionally, the unit is available with a hollow stem drill pipe allowing us to lower anodes in place in environments where an open hole may not be feasible. The rig is capable of drilling holes down to 100 feet deep, but for hollow stem purposes, we are limited to a depth of only 50 feet.

What This Means for Our Future

MATCOR is excited to add this new rig to our industry-leading inventory of cathodic protection installation enabling us to better compete for:

  • Shallow conventional anode beds
  • Distributive anode beds around tanks and congested facilities
  • Mobility is increased since it is loaded on to a semi-trailer

For more information, please contact us at the link below, or reach out to your local MATCOR account manager.

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At What Distance Does Cathodic Protection Continue to be Effective?

This article explores the answer to a question posed by a student about the length of pipeline protected by a cathodic protection system.


What length of pipeline is protected by a cathodic protection system?

We recently received a question from our website from someone who self-identified as a Student. We love when people ask technical questions and are pleased that students visit the MATCOR website–we have always strived to have a content-rich website to help share CP knowledge. The question is as follows:

“For installed impressed current CP systems with 15 anodes, what would be the approximate radius/length of a 200-mile petroleum metal pipe that would be protected?”

So before diving into the answer, let’s frame this question with an assumption, identify some unknowns and provide a definition.

Assumption

The 15 anodes are part of a single anode bed. The anodes are electrically remote from the pipeline and connect to an appropriately-sized DC power supply (transformer/rectifier, solar power/battery unit, thermoelectric generator, etc.)

Unknown #1: Pipeline Details

Before doing any detailed engineering, there are a few details that must be specified:

  • Pipeline diameter and material of construction
  • Coating type and condition
    • The layout of the pipeline (location of pumping stations, valve stations, and metering stations)

Unknown #2: Soil Conditions

Understanding soil resistivity in terms of location, frequency, and spacing, is critical when designing cathodic protection systems for long-length pipelines.

Definition of Attenuation

a lessening in amount, force, magnitude, or value according to Merriam-Webster

When discussing at what distance cathodic protection continues to be effective along a pipeline, you must consider the attenuation of the CP current. At some point, the current diminishes along the length of the pipeline, becomes insufficient, and can no longer protect the pipeline.

The Answer: Impressed Current CP Systems are Complicated

We can effectively use attenuation calculations for signals generated on a uniform conductor and transmitted through a uniform environment.

In this case, the pipeline is not a uniform conductor; unless it is bare, it is anything but uniform. The coating has less than perfect effectiveness and an unknown number of defects distributed in an unknown manner. The environment is equally non-uniform; soil resistivities change based on location and weather changes. The more non-uniformity, the more inaccurate the results will be for any attenuation calculations.

It is virtually impossible to model mathematically for older pipelines with insufficient coatings. The only effective strategy is to collect data by installing a temporary current source to measure the effective current throw in each direction in multiple locations along the pipeline.

For new pipelines with very good coatings, it is possible to perform some attenuation calculations and empirically determine a reasonable separation distance between anode stations.

The math starts with determining something called the propagation or attenuation constant. To calculate this, take the square root of the resistance per unit length of the structure divided by the leakage conductance per unit length.

In Simple Words…

How hard is it for the current to travel along the pipeline versus how easy it is for the current to jump onto the pipeline?

The smaller this number, the further current will spread. Key factors affecting the attenuation constant include earth resistivity (higher resistivity soils mean further current spread) and coating quality (better coating means further current spread). Armed with this, there are six simultaneous equations that we can use, and that include hyperbolic sine and cosine functions.

Larger, new construction pipeline projects require you to consult with a professional engineer. A brief newsletter article will not adequately cover the mathematical gymnastics involved. We did say that the math is complex.

Well-coated, newer pipelines in moderate to high-resistivity soils can typically be protected for 20+ miles in each direction from an anode bed. Poorly-coated or bare pipelines in low-resistivity soils may require anodes every quarter mile or less.


Need more information? Please contact us at the link below.

Is My Tank CP System Working Correctly?


Ted Huck, Director of Manufacturing and QA/QC at MATCOR, recently published an article in the summer edition of Tanks and Terminals Magazine titled “Understanding Cathodic Protection Systems.” He explains how to assess the performance of cathodic protection systems for above-ground storage tank bottoms (Tank CP Systems).

When asked to summarize these performance assessments, Mr. Huck commented, “Tanks are pretty easy to test, except for those rare occasions when they are not. At that point seek professional help.”

Read the full article.


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

Three Ton Sled Anode Assemblies Head to Beaumont, Texas

MATCOR shipped four of the heaviest customer sled anodes we have ever fabricated this month – over three tons each. Headed to Beaumont, TX, the anodes are part of a Gulf Coast refinery expansion project. The anodes will protect a variety of marine piling structures as part of a light crude processing expansion at the refinery.

Sled Anode assembly – pouring the concrete bases.

Each anode is rated for 75 amps and weighs approximately 6300 pounds. Each anode assembly consists of a pair of two-inch diameter Mixed Metal Oxide coated titanium tubular anodes, five-foot-long. The anodes utilize MATCOR’s proprietary tubular anode connection technology for larger diameter anode tubes. Each sled anode has two concrete bases resting on a common wood base fabricated with stout 6” x 6” pressure-treated wooden beams. The concrete ends include lifting lugs to support installation by crane either from land or on a work boat. The function of the treated wood beams is to sink into the sea floor.

Completed Sled Anode assembly – waiting on the concrete to cure.

The anode lead cables are dual insulated HMWPE/ Kynar 1/0 cables housed in a proprietary HDPE jacket and held in place along the sea floor using concrete weights.

Sled Anodes are an exceptionally cost-effective means of protecting large near-shore structures such as dolphins, jetties, pilings, and sheet pile walls. They are easy to install and even easy to remove in advance of dredging operations.

More Information About MATCOR’s Sled Anode Products

Marine Anode Sled Product Page

Houston Sled Anode Installation

[YouTube Video] MATCOR Sea-Bottom™ Marine Anode Sled

[Materials Performance Case Study] Impressed Current Anode Systems for Jetty Piling


Need information or a quote for MATCOR custom sled anodes? Please contact us at the link below.

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.

Cathodic Protection Systems | Cathodic Protection Design | alternatives to sacrificial anodes and galvanic anodes