Category Archives: Pipeline Integrity

Linear Anodes for Hard-to-Reach Places [Rusty Talks]

Rusty and Josh Johnston chat about a recent project and case study involving the use of linear anodes for hard to reach places.


This month, MATCOR exhibited at the AMPP Central Area Conference held in Kansas City. MATCOR’s Mr. Josh Johnston, along with Mr. Chad Farris of Energy Transfer, jointly presented a paper—a case story using linear anodes as a shallow horizontal anode bed installed along two pipelines in central Kansas.

Rusty: Josh, tell us how it felt to finally be in a real-life conference interacting with people in person after the last year and half of cancelled conferences and virtual conferences.

Josh: It is always great to get to interact with our friends and industry colleagues, clients, suppliers and competitors to share information and discuss the challenges that our industry faces—especially given the events of the past couple of years. Presenting this paper was a great opportunity to highlight the use of linear anodes to protect hard to reach areas on older pipelines.

Rusty: Can you describe the problem that you covered in your presentation?

Josh: Energy Transfer had two older pipelines that were not meeting criteria in a rural location. As is typical in a lot of pipeline cathodic protection applications, the pipelines were being protected by impressed current anodes located at road crossings where power was readily available. The roads ran parallel to each other and were located one mile apart. The pipeline traversed these two roads and the area in between was mostly farmland. As a result of the age and coating condition, the shallow horizontal anode beds, located at the road crossings, were not able to project much more than a ¼ mile from each end, leaving approximately ½ mile in the center under protected. This was clearly identifiable in the close interval survey (CIS) data.Linear Anodes for Hard to Reach Places

Rusty: Couldn’t they simply increase the current output of the existing shallow ground beds at each end of the pipeline to drive more current to the center section in between?

Josh: They tried that approach, and it did not work, raising concerns that driving excessive current onto these older pipelines could actually make the situation worse by further disbanding any coating close to the existing ground beds.

Rusty: So where did MATCOR come into this project

Josh: MATCOR proposed linear anodes be installed parallel to each of the pipelines in the area between the two roads. MATCOR developed the very first MMO (mixed metal oxide) linear anodes over 30 years ago and we have the most experience designing linear anode CP systems.

Rusty: So it sounds easy, you take a couple of ½ mile segments of linear anode, trench them in parallel to pipeline and run a couple of long extension cord cables back to the road where there is power.

Josh: Well it does sound easy; however, in practice it is critical that any linear anode design carefully addresses voltage drop, and that the power feed cabling is configured so that each anode segment output is balanced. If this is not engineered properly, you could have a large disparity in the voltage being applied on one end of the anode segment relative to the other end. This would result in a very uneven distribution of current. Discussing the design considerations for the power feed cabling was the primary focus of this presentation.

Rusty: So how did it work out?

Josh: MATCOR was able to use some creative cabling analysis and routing to assure that the voltage difference from one end of an anode segment to the other was no more than a 10% variance. The post installation and commissioning CIS data delivered an outstanding current distribution.

Rusty: Thanks for providing a very quick overview of your presentation—any final thoughts or comments?

Josh: When designed properly, linear anodes can be a real problem-solving solution for older pipelines with current distribution and attenuation issues.

Oh yeah, Kansas City BBQ still rocks!

Have questions or need a quote for linear anodes or installations services? Contact us at the link below. For immediate assistance, please call +1-215-348-2974.

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Pipeline Internal Corrosion Prevention with VCI

MATCOR recently completed a significant pipeline preservation project at a newly constructed pipeline station in West Texas. The project involved injecting Zerust Vapor Corrosion Inhibitor into multiple above ground pipeline manifolds to prevent internal corrosion. The rest of the pipeline remains under construction.

Using vapor corrosion inhibitors (VCI) to protect internal pipeline surfaces is an established technology proven very effective for pipelines post hydrotest.

Preparing for VCI Installation for pipeline internal corrosion prevention

Typically, all pressure-containing piping requires hydrotesting once the piping fabrication is complete. This ensures that there are no faulty welds and that the piping system can handle the design pressure without any leakages.

This fitness for service testing, unfortunately, introduces water and possibly bacteria into the piping. After the hydrotest is completed, and the water is drained, there remains residual moisture (and potentially bacteria) that can prove very corrosive even with efforts to dry the internal surfaces.

For pipeline preservation applications, the VCI chemical is typically mixed with water into a slurry. Then, it is pumped into the piping manifolds using a series of injection pumps and injection ports through hoses from multiple mixing tanks.

How Does VCI Prevent Pipeline Internal Corrosion?

The VCI molecules diffuse and adsorb to the surface, forming a very thin (molecular level thin) protective layer that blocks water and oxygen from reacting with the internal metallic surface of the piping. The molecular level VCI barrier, when properly applied, can last for months and even years as the balance of the pipeline construction is completed.

For this project in West Texas, MATCOR prepared and installed over 24,000 gallons of VCI Solution inside the piping manifolds after their fabrication and testing. Because of the above ground nature of the project, we added methanol (anti-freeze) to the VCI slurry mixture to provide freeze protection for the winter months.

In addition to pipeline preservation projects, VCI is a great product for tanks and pipeline casings.


To get in touch with our team of cathodic protection experts for more information, to ask a question or get a quote, please click below. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

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Turnkey Project Includes Pipeline Recoating & CP Upgrade

Working with fellow BrandSafway company Industrial Specialists LLC, MATCOR successfully completed a turnkey pipeline recoating and cathodic protection upgrade project ahead of schedule and to the operator’s complete satisfaction.

pipeline recoating project
MATCOR & Industrial Specialists team up on a complex pipeline recoating project.

Earlier this year, MATCOR purchased two state of the art dual air/hydro vacuum excavators. We have put these units to work as we expand our capabilities to include pipeline recoating services.

“We recently completed a major project in Oklahoma for a midstream client that leveraged our ‘Big Air’ vacuum excavators. This complex project challenged our existing capabilities and allowed us to draw on the resources and capabilities of our parent company, BrandSafway, to provide a full service cathodic protection upgrade and pipeline recoating in multiple locations.”—Josh Johnston, MATCOR Director of Sales

Pipeline Recoating Added to Anode Bed and Test Station Installation

The project consisted of six (6) anode bed installations and seven (7) test station installations – standard CP work for MATCOR; however, at each of the test station locations, we were also tasked with coating removal and recoating of the approximately 20 ft of pipeline exposed at each location.

The coating removal was complicated by the presence of asbestos. Prior to 1980, asbestos was typically used in a felt wrapping around the pipe along with an asphaltic (tar) outer wrap.

Asbestos can still be found in the coating of hundreds of thousands of feet of buried pipeline installed prior to 1980. MATCOR’s crew received one week of asbestos removal training to be properly qualified to identify, remove and dispose of the coating containing asbestos.

MATCOR’s parent company, BrandSafway, has in its portfolio of businesses Industrial Specialists, LLC (IS), which is an extremely well-qualified industrial coatings services team with over 35 NACE trained and certified inspectors and over 1,700 painters and supervisors.

MATCOR was able to partner with the IS Tulsa, OK office to deliver the entire project using in-house BrandSafway resources, making us a one stop shop for this level of work. MATCOR’s CP construction crews performed the vacuum excavation and asbestos coating removal, and then the BrandSafway industrial services crew performed the blasting, inspection and recoating work. One big company with a wide range of industrial capabilities.

Project Completed Ahead of Schedule

The project was executed successfully, completed two weeks ahead of schedule and to the pipeline operator’s complete satisfaction. We even identified two areas where the pipeline was directly on top of rock and the owner asked that MATCOR install a layer of rock shield over the completed recoat areas. At the end of the project, the pipeline operator affirmed that they would be using MATCOR again for similar project work.


Have questions or need a quote for cathodic protection or pipeline recoating services? Contact us at the link below.

CONTACT A CORROSION EXPERT

Pipeline Corrosion — All You Need to Know

This article provides an overview of pipeline corrosion in the United States, the two categories of corrosion in pipelines and the primary methods of prevention.

Corrosion of Pipelines in the United States

pipeline corrosion prevention

The United States has over 2,225,000 kilometers of pipelines, the vast majority of which are transporting oil and natural gas. No other country comes close—Russia is a distant second with approximately 260,000 km of pipelines.  The US Pipeline network consists of hundreds of public and private companies that own and operate these pipelines within a national regulatory framework managed by the US Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA).  While pipelines have proven to be exceptionally efficient and very safe—pipelines are roughly 70 times safer than trucks1 and 4.5 times safer than rail2—the aging network of pipelines continues to be of concern because much of the nation’s pipelines are at least 50 years old and getting older.

Pipeline Corrosion Prevention Mitigates Devastating Failures

Corrosion is one of the biggest problems contributing to leaks and ruptures of pipelines. Corrosion is the natural process where materials made from metal electrochemically react with the environment and deteriorate.  Without proper engineering and preventative maintenance, this deterioration from the natural process of corrosion will result in an increasing frequency of pipeline incidents.  The good news is that with proper pipeline monitoring and maintenance, corrosion is completely manageable. Operators can utilize existing technologies to ensure the integrity of these critical assets and prevent damaging failures.

Two Categories of Corrosion in Pipelines

Pipeline corrosion can be broken down into two primary categories.  Internal Corrosion, which causes approximately 12% of all incidents, occurs on the inside of the pipeline, while External Corrosion, which results in approximately 8% of all pipeline incidents, occurs on the outside of the pipe. 

Pipeline Corrosion Protection Strategies for External and Internal Corrosion

Two primary mitigation strategies are employed to prevent external corrosion of pipelines:
  1. Pipeline coatings
  2. Cathodic protection

When these mitigation strategies are properly employed, monitored and maintained, steel pipelines can last indefinitely. While this sounds simple, pipeline coatings are never perfect and are themselves subject to damage during construction and degradation over time, while cathodic protection is a complex process that requires continuous monitoring and extensive testing, combined with regular maintenance to be effective.

Internal corrosion, in most cases, is a result of contaminants naturally occurring in the product being transported by the pipeline. Common contaminants include oxygen, hydrogen sulfide, carbon dioxide, chlorides, and water.

Many variables can affect the nature and extent of a particular internal corrosion reaction on a pipeline:
  • Contaminant concentrations
  • The combination of contaminants within the pipeline
  • Operating pressure and velocity
  • Pipeline geometry and holdup points
  • Operating temperature
  • Other factors
The primary pipeline internal corrosion prevention strategies include:
  • Controlling or minimizing contaminants prior to transporting them in the pipeline
  • Internal pipeline coatings
  • Injection of corrosion inhibitors
  • Increased frequency of internal pipeline cleaning to remove the accumulation of contaminants

For controlling both external and internal corrosion, regular monitoring and testing programs combined with the appropriate mitigation strategies, are a critical part of any pipeline integrity management program.  When performed properly, corrosion can be effectively controlled, assuring that pipelines remain safe from corrosion indefinitely.

1 propublica.org – Pipelines Explained: How Safe are Americas 2.5 Million Miles of Pipelines?

2 fraserinstitute.org – Pipelines are the Safest Way to Transport Oil and Gas


To get in touch with our team of cathodic protection and AC mitigation experts for more information, to ask a question or get a quote, please click below. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

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PHMSA Mega Rule Update

PHMSA Mega Rule
The PHMSA Mega Rule significantly impacts the US pipeline industry.

It has finally landed – the PHMSA MEGA rule has hit and will have a tremendous impact on the US pipeline industry, adding significant scope to the current pipeline integrity management requirements.  Some of the industry impacts that the PHMSA MEGA rule will have include:

  • An approximately 20% increase in the number of regulated pipelines in the United States
    The exact impact depends on some additional details not yet released; however, it is very clear that the addition of 20% more regulated pipelines will have a significant impact on an industry where highly qualified integrity professionals and related services are limited in supply and the industry is already struggling to meet demand.  These additional pipelines will require significant integrity resources.
  • Expedited reporting requirements
    The time restrictions for implementing the new rule have been accelerated, with initial reporting requirements in July, 2020, less than a year away. Time to comply with these regulations has been reduced 20% from the initial draft order timeline.
  • Increased cathodic protection requirements
    Many pipelines that previously were not regulated and have not had proper CP will now require a properly designed, maintained and tested cathodic protection system.

The PHMSA MEGA rule will be a challenge and an opportunity for MATCOR as midstream pipeline operators will be looking for partners to help them address these new regulations.  MATCOR provides a full range of cathodic protection and pipeline integrity services including:

  • Field Integrity Surveys
  • ECDA
  • CP Assessments
  • CP Design
  • CP Installations
  • Annual Testing Services
  • Test Station Installations
  • Remote Monitoring
  • CP Maintenance
  • AC Interference

It is going to continue to be exciting times in the midstream market.

Learn more about PHMSA regulations.


To get in touch with our team of cathodic protection experts for more information, to ask a question or get a quote, please click below. We will respond by phone or email within 24 hours. For immediate assistance, please call +1-215-348-2974.

Contact a Corrosion Expert

Cathodic Protection Remote Monitoring

This article provides a brief overview of the important role of cathodic protection remote monitoring systems in today’s pipeline operations. We will cover the CP equipment and features that can be monitored and how data is transmitted.

cathodic protection remote monitoring
Advanced cathodic protection remote monitoring systems are critical for today’s pipeline operator.

Modern pipeline operations face increasing pressures to incorporate advanced technologies to:

  • Drive down operating costs
  • Improve system reliability
  • Comply with regulatory requirements
  • Monitor the health of their pipeline networks
  • Monitor the critical systems that are integral to pipeline integrity

The use of advanced cathodic protection (CP) remote monitoring systems has become a critical component in the pipeline operator’s toolbox to meet these challenges.

CP remote monitoring (and control) has proven to be a reliable and cost-effective means to oversee the proper functioning of cathodic protection systems and AC Mitigation systems that are critical to assuring pipeline integrity and the proper protection against pipeline corrosion. Where operators in the past would have to send technicians out to remote pipeline locations to collect snapshot data on a frequent basis, the smart deployment of CP remote monitoring systems can provide continuous real time data that can be accessed from any cloud connected handheld or desktop device. Additionally, a remote monitoring unit for cathodic protection is well-insulated; this construction affords them excellent protection against lightning strikes. The financial, environmental and safety impact of eliminating hundreds of thousands of windshield hours is staggering across the vast pipeline industry.

Cathodic Protection Remote Monitoring – What can you monitor?

  • Cathodic Protection Rectifiers – the installation of RMUs with built in interruption capabilities should be standard on all new pipeline installations and retrofitting older units can provide significant cost savings and improve CP system reliability.
  • DC Cathodic Protection Test Stations – with today’s continuing advances in remote monitoring technology and costs, it is quickly becoming very cost effective to install remote monitoring units on all test stations. When combined with the ability to easily interrupt all of the influencing current sources on a pipeline, regularly scheduled testing of the CP system can be performed quickly and at virtually no cost.
  • AC and DC Coupon Test Stations – the latest NACE guidelines for AC Mitigation (SP21424-2018*) emphasize that the localized DC current density has a significant impact on AC corrosion and gathering data on both AC and DC current densities at areas of interest/risk is critical to a successful AC Mitigation strategy. Effectively doing so requires the ability to monitor these values over time as AC loads vary during the day and seasonally.
  • Critical Bonds – monitoring the effectiveness of critical bonds is necessary (and in many cases required by local regulatory bodies) to assure pipeline integrity.

NACE SP21424-2018 “Alternating Current Corrosion on Cathodically Protected Pipelines: Risk Assessment, Mitigation, and Monitoring”

How does a CP remote monitoring system transmit data?

remote monitoring unit cathodic protection
Mobiltex Cathodic Protection Remote Monitoring Unit (CP RMU)

Today’s operators have a range of options to assure that remote monitoring systems can regularly communicate data to their host data collection systems. The availability of conventional cellular networks combined with various commercial satellite systems assures pipeline operators of the ability to communicate with devices in even the remotest of locations. Your monitoring system provider can work with you to select the appropriate communications technology for each CP remote monitoring unit (CP RMU) location.

In addition to choosing how the communication is to occur, another key factor to consider is whether the communications are to be one way (monitoring only) or two-way (monitoring and control). For test station applications where data collection is the goal, one way transmission of the monitoring unit’s data is all that is required. For rectifier units, the ability to control the system output and/or the ability to initiate an interruption cycle for close interval surveys or test station polling purposes necessitates the ability of the cathodic protection remote monitoring unit to receive and act on communications as well as to transmit data.

Software Interfaces – Installing the appropriate CP RMU hardware is just one step in implementing a successful remote monitoring (and control) program. The data must be collected, stored, and accessible for the operator. Sophisticated cloud-based interfaces have been developed that incorporate critical features including firewall-friendly, password protected internet browser access. These systems allow for multiple client user accounts with configurable permission levels and automated alarm and status information including email and text alerts for designated alarm conditions.

In summary, the use of remote monitoring technology is a key component to the successful operation of any modern pipeline integrity management program. While MATCOR has extensive experience with all of the major RMU manufacturers, we have recently teamed up with Mobiltex, a leader in the field of remote monitoring, to bring state of the art technology to the pipeline and cathodic protection industry. Mobiltex’s CorTalk® line of CP RMU units combined with their CorView interface offers all the features necessary to implement a comprehensive, cost-effective, and highly robust cathodic protection remote monitoring program.


Please contact us at the link below if you have questions about cathodic protection remote monitoring, or if you need a quote for services or materials.

CONTACT A CORROSION EXPERT

PHMSA Rule Making Updates – a look at what is ahead on the US Regulatory Front

See our October 2019 Update on the PHMSA Mega Rule.

Overall
The US Pipeline regulatory environment is poised to see several new rules implemented to expand the scope and effectiveness of pipeline regulations with a goal to improve the integrity and safety of hazardous material pipeline. These rule changes were all initiated years ago and have been winding their way through the regulatory process, soliciting input from the industry and from concerned citizens, environmental groups and other interested parties.

The Liquids “Final Rule”
In January of 2017 in the last few days of the Obama Administration, the Department of Transportation’s Pipeline and Hazardous Materials Safety Administration issued a final rule amending its Rule 49 CFR 195 that among other things expanded integrity management and leak detections beyond high consequence areas (HCA’s). The Final Rule tightened standards and broadened data collection and monitoring requirements for pipeline operators. A few days into the Trump administration, the White House issued a directive to federal agencies to freeze sending new regulations to the Office of the Federal Register (OFR) and withdrawing any regulations sent to the OFR. Thus the liquids “Final Rule” that was 6 years in the making was withdrawn and is awaiting resubmittal by the new administration.
While the exact requirements of the Final Rule may be changed, some of the key changes from the withdrawn rule included:

• Assessment of non-HCA pipeline segments every 10 years in compliance with provisions of 49 CFR Part 195.
• Increased use of inline inspection tools for all hazardous pipelines in HCA.
• Requirement for leak detection systems for covered pipelines in both HCA and non-HCAs.

PHMSA anticipates coming out with their revised “Final Rule” in the Fall of 2018.

The Gas “Mega Rule”

On the gas side of the pipeline regulatory environment, 49 CFR Parts 191 and 192, several public meetings have been held regarding PHMSA’s proposed gas rules, often referred to as the Gas Mega Rule. The rulemaking changes originally recommended would have nearly doubled the current number of pages in the regulations. PHMSA has announced that instead of one Mega Rule, the effort would be broken into three separate rules that are expected to be introduced in 2018 and to go into effect in 2019. Part 1 addresses the expansion of risk assessment and MAOP requirements to include areas in non-High Consequence Areas (HCAs) and moderate consequence areas (MCAs.) Part 2 of the rule making focuses on the expansions of integrity management program regulations including corrosion control to gathering lines and other previously non-regulated lines. Part 3 of the gas rule making is expected to focus on reporting requirements, safety regulations and definitions to include expanding into related gas facilities associated with pipeline systems.

Remediation Options for Aging Pipeline Coating Systems

A linear anode system may be an economical alternative to applying a new pipeline coating system or replacing aging pipelines.

by Ted Huck

Introduction: Addressing Aging Pipelines and Pipeline Coatings

aging pipeline coatingExternal corrosion is one of the significant threats facing pipeline operators worldwide. Historically, pipeline owners have employed a two-tiered approach towards mitigating corrosion risks. The primary defense against corrosion has been to apply a pipeline coating system that acts as a barrier, protecting the steel pipe from its environment. Cathodic protection is employed to supplement the coating system by providing protective current to the holidays or defects within the coating system. As with any aging structure, however, time takes its toll – for older pipelines this often results in an older coating system that starts to degrade in its primary function of protecting the pipeline from its environment.

This paper addresses the fundamental issue that many operators will face when evaluating their aging pipelines and pipeline coating systems. That issue is, quite simply, what is the best strategy to remediate an aging pipeline with deteriorating coating systems to maintain compliance with international standards for pipeline integrity. The options are to improve/upgrade the cathodic protection system, recoat the pipeline, or replace the pipeline. Each of these options will be discussed in detail and a decision matrix will be provided to facilitate the operator’s decision-making process.

Pipeline Coating Systems

Coating systems have been used on buried pipelines during the last hundred years and the technology continues to be the subject of significant research and innovation. Pipeline coating manufacturers are continually searching for better coatings to meet the varied needs of industry. Initially, the coatings were simple mixtures of crude pitches and solvents. These early bitumastic/asphaltic systems evolved into engineered coal tar enamel coating systems, which were prevalent into the 1960’s. The introduction of fusion-bonded epoxies (FBE) in the 1970’s quickly captured much of the pipeline market, although polyethylene, polypropylene and coal tar enamels are still used as well. The coatings industry continues to research and develop improved methods of providing more reliable and more economical coating systems.

When evaluating aging pipelines, coating condition is one of the critical issues that must be addressed. The coating provides the primary defense against pipeline corrosion and as the coating system ages and deteriorates, then the risks of corrosion increase exponentially. One of the challenges that must be addressed by pipeline owners is properly identifying the type and vintage of the coatings along a given pipeline. In many cases, different sections of pipeline may have different coating systems depending on the age of the pipeline and the standards in place at the time a section of pipe was installed.

Another critical consideration when evaluating aging pipeline coating systems is to identify whether the coating system fails shielding or non-shielding. Coating systems that fail in a non-shielding mode do not inhibit the flow of current making cathodic protection a viable alternative when considering how to remediate these lines. Other coating systems, principally tape coating systems, can fail in a manner that shields cathodic protection current and thus greatly reducing the possible remediation methods available.

Modern, over-the-line survey technologies have proven to be quite effective in evaluating coating quality and finding coating holidays. Technologies such as pipeline current mapping (PCM) which utilize a carrier signal transmitted along the pipeline with a receiver measuring the line attenuation along the pipeline length can accurately pinpoint areas of significant coating degradation even under concrete or asphalt. The information gathered using PCM in conjunction with pipe to soil close interval surveys (CIS) and direct current voltage gradient (DCVG) testing form the basis for identifying critical risk areas along aging pipelines. In-line inspection technologies using smart pigs also provide valuable data regarding coating quality.

Cathodic Protection

Pipeline coating systems are typically augmented by the application of cathodic protection. With a well-coated pipeline, cathodic protection can be economically applied to protect the coating holidays and defects by placing discreet anode beds that distribute current over long distances. In many cases ground beds can be located several kilometers apart and still provide sufficient current distribution to protect the entire pipeline. With some of today’s high technology factory applied coatings, the coating efficiencies are exceptionally high and the groundbed output requirements are very low. These discreet ground bed systems can either be deep anode ground beds or shallow ground beds located some distance off the pipeline.

Several issues must be considered when designing a cathodic protection system. These include coating quality, soil resistivity, available locations for electrical power, ground bed right of way issues, accessibility for maintenance, AC and DC stray current interference, and a host of additional issues. What is critical for aging pipelines is the regular evaluation of the effectiveness of the CP system. Frequently, as pipelines age and the coating quality begins to deteriorate, the CP systems are unable to provide sufficient current properly distributed to meet established cathodic protection criteria. In many cases, simply ramping up the output of the existing system or adding additional ground beds does not prove sufficient to address the problem.

Learn about soil resistivity testing.

Aging Pipeline Systems

Problem Identification

Aging pipeline systems with deteriorating coating systems suffer from poor current distribution and are characterized by areas of low potentials and exceedingly high levels of applied current density. The challenge with these pipeline systems is controlling current distribution to achieve the prescribed polarization levels consistent with international standards for adequate cathodic protection.

Figure 1 shows a deep well anode system with current output such that some areas are not meeting required off-potentials of -0.85 Volts to meet NACE criteria.

pipeline coating - insufficient cathodic protection

Initial Responses

The typical response to this problem is to increase the overall output of the deep well system (see Figure 2.) This generally does not alleviate the problems of not meeting the off-potential criteria and leads to over-polarizing the piping (potentials greater than -1.2 Volts.) This can result in coating disbondment further exacerbating the problem. The higher output current increases the ground bed’s consumption rate reducing operating life while raising operating costs appreciably. All this occurs without achieving the required levels of polarization to meet cathodic protection criteria.

pipeline coating - increased cathodic protection output

The next step that is taken to fix the cathodic protection current distribution problem is to add additional ground beds to reduce the distance between point sources. This too, proves to be an ineffective solution as the new ground bed provides only limited additional benefit (see Figure 3.)

pipeline coating - additional cathodic protection ground beds

Remediation Options

The problem cannot be economically resolved by the addition of an ever-increasing number of ground beds applying greater and greater amounts of additional current. The pipeline operator is then faced with a limited number of options: recoat the pipeline, replace the pipeline, or install a linear anode cathodic protection system.

Recoating/replacing is the only viable alternative for pipeline systems utilizing shielding type coatings such as tape wrap systems. Recoating costs typically run several hundred dollars per foot in open right of way areas and can be significantly more expensive in congested urban locations (these are ballpark numbers applicable to the United States and can vary significantly.) Recoating, when properly performed, can restore the pipeline coating system to an as new condition greatly extending the service life of the recoated section. The critical issue is to assure that the recoating is executed by an experienced coatings contractor with rigorous quality controls in place. Pipeline replacement is expensive and only performed when extensive third-party damage, significant corrosion or other extenuating circumstances warrant.

An economically attractive alternative to recoat/replace options is to utilize a linear anode configuration in lieu of point anode systems. This option is only viable when the coating system is non-shielding – this would include asphaltic and epoxy type coating systems. The application of a linear anode system typically costs between $20-30/foot in open right of way (again these are general price guidelines and can vary significantly.) In suburban or urban areas, horizontal directional drilling (HDD) can be an effective installation method with minimal surface disruptions. These linear anode systems eliminate the distribution problems experienced by point anode systems; they are in effect an infinite series of point anodes, which provide an optimum current distribution (see Figure 4.)

pipeline coating - linear anode system for optimum current distribution

In addition to confirming that the pipeline coating system is non-shielding and appropriate for the application of linear anodes, the linear anode system design must take into consideration the critical issue of voltage drop and its affect on current attenuation. Voltage drop can have a significant impact on DC power distribution to the linear anode system. Ideally, rectifiers would be located no further than half a mile to a mile apart, however, practical considerations including availability of AC power, right of way issues and other factors can force this to be extended further complicating the system design and affecting the installed cost.

While the design can be complicated by voltage drop considerations, one of the benefits of a linear anode system is that the power consumption is relatively low. Ground bed resistance, as determined by Dwight’s Equation, is significantly affected by anode length and this results in very low groundbed resistance values for linear anode systems relative to conventional ground beds. This makes the linear anode system much more suitable for low wattage power sources such as solar arrays and thermo-electric generators (TEG’s) than conventional ground beds whose wattage could be two or more times that of a linear anode system to achieve the same current discharge.

Conclusion

Aging pipeline systems with deteriorating coating systems present a difficult challenge to pipeline operators. The more the coating deteriorates, the more difficult it is to distribute current further away from the ground bed. The natural response to ramp up the ground bed output does an inadequate job of throwing current further but does result in increased current flow, higher current densities and over polarization near the ground bed further stressing the coating system. Adding additional ground beds also allows more current to be applied to the pipeline, but does not alleviate the current distribution issues. Ultimately, pipeline operators are faced with the choice of recoating/replacing the pipeline, or installing a linear anode system. The flowchart below (Figure 5) provides a decision matrix. Note that aging pipeline systems whose coating systems are determined to be in good condition through indirect and direct examination, require additional investigation to determine why criteria is not being achieved.

Aging pipeline coating decision matrix


For assistance with evaluating aging pipelines or installing linear anode cathodic protection systems, please CONTACT US.

Pipeline Rehabilitation and “Attenuation Deficit Disorder”

Around the world, the pipeline industry is seeing a growing number of “attenuation deficit disorder” outbreaks along their older pipelines. This is not a disease or a medical condition afflicting pipeline company personnel, but is a reference to a growing global problem with pipeline cathodic protection (CP) systems that are affected by older coatings that are failing. Pipeline operators need a solution for pipeline rehabilitation.

Pipeline Rehabilitation Solutions

Pipeline Rehabilitation ArticlePipeline operators worldwide are grappling with what to do as their 1950’s, once state of the art coatings systems start to fail. In our recent article in World Pipelines, Ted Huck examines two possible solutions for pipeline rehabilitation:

  • Recoating the Pipeline: At some point in the process of adding more CP stations and increasing the current output to levels that further degrades the coating, it becomes apparent to the pipeline operator that more drastic measures are required.
  • Rehabilitating the Cathodic Protection System: Under the right circumstances, an attractive alternative to the recoat approach is to consider the use of linear anodes as a rehabilitation strategy.

For additional information about these pipeline rehabilitation solutions, please read the full article in the September issue of World Pipelines. You can access the article HERE.

For assistance with cathodic protection design, MATCOR’s linear anodes for pipeline cathodic protection, project management or installation, please contact us at the link below.

Contact a Corrosion Expert

Not Just a Walk Along the ROW: Close Interval Potential Surveys

Close Interval Potential Surveys (CIPS) or close interval surveys (CIS) for those in the United States, are an invaluable assessment tool used to maintain pipeline integrity. Close Interval Surveys are frequently mandated by pipeline regulatory authorities.

Keys to a Successful CIPS Survey

  • Selecting a qualified survey crew
  • Advanced planning
  • Selecting the appropriate CIPS Type
  • Accurate CIPS Data Collection
  • Expert Data Analysis and Reporting

Close Interval Surveys (CIS, CIPS)Learn more about the keys to a successful CIPS survey and other considerations in our recent article appearing in World Pipelines, “Not Just a Walk Along the ROW” by Ted Huck.

READ THE ARTICLE

Are you ready for spring close interval surveys?

MATCOR is here to help. Our experienced and NACE-trained crews are ready to perform close interval surveys to keep your pipeline cathodic protection systems in compliance and operating effectively.

  • Excellent safety record
  • Accurate, reliable data collection
  • Daily field progress reports
  • Extensive engineering and IT support

Contact MATCOR about your CIPS requirements or learn more about our close interval survey capabilities

 

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