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GIS Atmospheric and Soil Corrosion Map: Please Visit matergenicsgis.com For Additional Technical Details

 

Soil is a natural body consisting of layers (soil horizons) resulting from the interplay between climate, topography, organisms, parent material (underlying geologic bedrock), and time. Accurate soil data are needed in order to develop reliable and high-resolution soil corrosion maps for corrosion engineering analysis, corrosion protection, condition assessment t. The several items of information required for soil characterization, deriving from sources with different spatial resolution, can be  stored and managed within a geographic information system (GIS). Digital soil mapping (DSM) allows one to analyze the relationships between soil corrosion  properties and ancillary data (e.g., topographic attributes and remote/proximal sensing data) through several pedometric techniques. .

Team Matergenics is one of the first companies to pioneer the integration of GIS mapping into the corrosion world. Others are trying to follow, however, Matergenics is at the forefront of this innovative technology. While the premise for this technology is rather simple the data collection and analysis are complex.  In this technology, various factors which contribute to corrosion are individually mapped (for instance, for below ground corrosion these may include soli salinity, moisture content, soil types, etc.).  Once all individual maps are created, a proprietary weighting system is used to develop an overall corrosion risk assessment map which identifies areas of high, medium and low corrosion.  Field surveys are then made to confirm the accuracy of the map.  The key to this technology is finding accurate data and the development of an accurate weighting system.  Through its PhD research and previous work with customers, Matergenics has fine-tuned this technology to consistently develop accurate maps which its customers are able to use to maximize their corrosion mitigation resources.  We are experiencing increased demand from the largest US utility companies for our corrosion mapping services. SCE, ATC… and SDG&E, two major California utilities, are now utilizing these maps, and are requesting more for 2020.

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Please see  http://matergenicsgis.com For Additional Technical Details

The need to identify areas at higher risk for corrosion becomes more important as structures and coatings continue to age.  However, a utility’s territory may cover thousands of square miles, and they may need to maximize limited resources to effectively manage its below-ground corrosion issues. The best way to address this situation is to develop a corrosion risk assessment map to identify areas of high corrosion risk.  A corrosion risk assessment map will combine various properties of soil to identify areas of high, medium, and low soil corrosivity. With this map a utility company would be able to deploy its resources most efficiently to specific areas of identifiable high corrosion risk.

Above-grade and below-grade corrosion is of particular concern to aging, coated pipelines, water/wastewater and electric utility T&D in corrosive soils, as the aging structure will react with corrosive soil.  This condition will result in loss in thickness.  Stray AC current interference is another risk for pipelines.  However, consider that zinc anode ribbons used for AC mitigation may exhibit accelerated corrosion in certain corrosive soils.

Our corrosion maps can be used for corrosion risk assessment, DC/AC interference risk and mitigation, identifying areas that shielding/coating dis-bondment and can potentially cause localized corrosion, leaks, and possible explosions. Examples are provided in the proposal.

The soil corrosion risk assessment map uses data collected by the U.S. Department of Agriculture National Cooperative Soil Survey. Data for atmospheric corrosion maps are gathered from the National Atmospheric Deposition Program, NOAA, and the National Weather Service. All information is updated and improved annually. In combination with Matergenics’ soil corrosivity data, developed with and for other clients, our database is the most comprehensive.

We are confident that utilizing corrosivity maps as part of your integrity and corrosion risk program will be instrumental in providing the necessary data to locate high corrosion risk areas with a high confidence level and with the least amount of investment.

 

 

 

Pittsburgh Soil Corrosion Map

 

The Technical Approach to Constructing A Below-Grade Corrosion Risk Map:

Matergenics’ unique approach to soil mapping considers the following:

  • Examination of spatial patterns associated with the physical and chemical properties of soil. This evaluation leads to insights on overall corrosion risk, and answers questions on where to locate a new pipeline and substation infrastructure.
  • Identification of the least or most corrosive sites and possible sources of stray current for corrosion mitigation

Some layers that are incorporated into corrosion maps are:

  • Soil resistivity
  • Soil salinity
  • Soil pH
  • Soil type, including the clay content
  • Drainage characteristics
  • Possible presence of stray currents from nearby gas pipelines or other protected assets

The Matergenics project team involved in the development of the corrosion risk assessment GIS map will include the following personnel:

  • -level specialist; NACE-certified in corrosion, cathodic protection, coating, material selection / design
  • -level Professional Engineer (PE); NACE-certified in cathodic protection (CP2) and coatings (CIP1)
  • -level Technologist; with expertise in computer-aided design (CAD) and simulation
  • Corrosion Engineer; NACE-certified in cathodic protection (CP2) and experienced in failure analysis
  • GIS mapping scientist
  • Senior soil testing specialist

 

 

Pipeline Corrosion Map

Technical Approach-Matergenics’ approach considers the following:

  • Examination of spatial patterns associated with the physical and chemical properties of soil – in order to identify areas of high This evaluation leads to insights on overall corrosion risk, and answers questions on where to locate new pipeline and substation infrastructure
  • GIS identifies the least or most corrosive sites, and also locates access to sites and possible sources of stray current for corrosion mitigation

Some layers that are incorporated into corrosion maps are:

  • Soil resistivity
  • Soil salinity
  • Soil pH
  • Soil type, including the clay content
  • Drainage characteristics
  • Possible presence of stray currents from nearby gas pipelines or other protected assets
  • Corrosivity of the water table

Los Angeles Soil Resistivity Map

 

 

 

Sources of Data

  • Matergenics soil databases
  • Client’s database, if available
  • S. Department of Agriculture
  • Soil Survey Geographic Database (SSURGO) – the most detailed level of information for resource management, county planning, etc.
  • National Resource Conservation Service

The project consists of two phases:

  • In Phase I, the relevant data will be collected, categorized, and analyzed with respect to the project objectives. The information will consist of five distinctive sets of data.
  • In Phase II, a knowledge-based approach along with adequate and accurate equipment, and advanced techniques, will be used to collect, analyze, and verify the Phase I corrosion mapping.
  • Matergenics recommends that investigators should not only consider soil parameters, but also external corrosion sources – such as stray current and AC interference – in order to determine and comprehensively assess corrosion risks.

A proprietary method is utilized in Matergenics’ corrosion risk assessment. The method includes an algorithm to assign a corrosivity index to each location on the map based on soil properties , geological data , and external corrosion factors.  The accuracy of this algorithm has been field tested and proven in several projects.

Matergenics will also include maps for gas pipelines and transmission towers (if available), either of which may be a source for stray current corrosion.

A corrosion risk assessment map will combine various properties of soil to identify areas of high, medium, and low soil corrosivity. With this map a pipeline company would be able to deploy its resources most efficiently to specific areas of identifiable high corrosion risk.

The following demonstrate various examples of soil corrosivity mapping for utility structures and pipelines

 

Assessment of the Accuracy of the Corrosion Map:

In order to assess the accuracy of the corrosion map, various sites and sections will be selected from distinctly different service soil environments with varying corrosivity indices.

Field inspections will be performed to investigate soil corrosivity and corrosion risks at selected sites.  Matergenics will perform a statistical analysis to determine the appropriate sample size, so as to adequately represent the service territory.

Specific techniques used to detect underground corrosion activity include:

  1. Close-interval potential survey (CIS) is a well-known method to measure the “potentials” of buried pipelines. Matergenics can estimate corrosion penetration based on potentials, predictive modeling and, soil corrosivity.
  2. DC current measurements, if feasible.
  3. Direct current voltage gradient (DCVG) surveys.
  4. Electrochemical technique to assess the corrosion rate based on LPR (linear polarization resistance) on the bare surface of the pipe. The amount of material loss and formation of passive corrosion products on the metal surface affect the values of current and potential in a temporary polarization test, if “off” potentials are less than critical potentials required for corrosion protection. The measurements can be correlated to the current state of corrosion if the age and corrosion potentials are known.

Methods to determine soil corrosivity include:

  1. Soil resistivity measurement (per ASTM G57Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method), with different pin spacings to perform Barnes layer analysis. This allows calculating soil resistivity at specific depths.
  2. Soil sample collection at shallow and deep burials (if feasible, and depending on site condition) for laboratory analysis. Laboratory tests include the following for soil corrosivity assessment and determination of input parameters for a predictive corrosion rate model:
  3. Instantaneous corrosion rate measurement (for steel) in mils per year (mpy), per ASTM G59; Standard Test Method for Conducting Potentiodynamic Polarization Resistance Measurements, and ASTM G102; Standard Practice for Calculation of Corrosion Rates and Related Information from Electrochemical Measurements
  4. As received and saturated soil resistivity measurement per ASTM G187; Standard Test Method for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method
  5. Moisture content measurement, per ASTM D2216; Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
  6. Salt contaminations for the following water soluble salts:
  • Chloride per ASTM D51;: Standard Test Methods for Chloride Ion in Water
  • Sulfate per ASTM C1580; Standard Test Method for Water-Soluble Sulfate in Soil
  • Sulfide per ASTM D4658; Standard Test Method for Sulfide Ion in Water
  1. Soil pH measurement, per ASTM G51; Standard Test Method for Measuring pH of Soil for Use in Corrosion Testing

Soil redox potential measurement, per ASTM G200;Standard Test Method for Measurement of Oxidation-Reduction Potential (ORP) of Soil

 

 

We perform thousands of soil corrosivity analysis every year and our crews can provide accurate soil corrosivity and confirm the the corrosion map by on-site soil corrosivity risk assessment.

GIS Atmospheric Corrosion Map

Our assessment of atmospheric corrosivity is based on international standard ISO 9223. The classification is based on SO2 pollution, chloride deposition, and time of wetness considering wind loads. These results, in addition to geostatistical approach will provide a map of atmospheric corrosion in region of interest.

Corrosion cannot take place without the presence of moisture(electrolyte) and corrosive ions. The time of wetness is a measure of how much time the material will be in contact with a conducting solution. Wet surfaces are caused by factors such as dew, rainfall, melting snow, or high humidity. These conditions are estimated by looking at the time during which the relative humidity is greater than 80% at temperatures greater than 0 °C.  Sulfur dioxide pollution is another major cause of atmospheric corrosion, and it is more prevalent in industrial and urban environments. Chlorides are a known corrosion risk for several reasons. They are a major component of most salts, which accelerate corrosion due to their hydrophilic nature. When a salt attracts water and dissociates, it produces a highly conductive electrolyte. Moreover, chlorides are a main catalyst for pitting corrosion, which is an autocatalytic, localized attack. Chlorides are known to cause hydrolysis and create acidic chlorides. Corrosion products that contain chlorides are typically more soluble than those that contain oxides. We will monitor airborne salts carried by the wind from the ocean. Airborne chloride concentrations are not monitored by weather stations and the models that we use to determine them are only accurate up to a few miles from the shore. As such, most estimates using the model in conjunction with ISO 9223-1992 will be utilized for atmospheric corrosion maps. On-site measurements will be used to obtain more accurate deposition rates for chlorides, sulfates and time of wetness per ISO 9223-1992.

 

 

These three factors are combined to determine an overall corrosion environment classification. Based on the classification, the corrosion rates are estimated based on Matergenics’ existing data. For example, our estimates show that Los Angeles is typically either C3 or C4 (moderate to high corrosion rates). For carbon steel, this equates to 25 to 80 µm/year. For zinc, this equates to 0.7 to 4.2 µm/year. This agrees with data from the American Galvanizers Association (21.4 µm/year for carbon steel and 1.09 µm/year for zinc). It should be noted that this assumes that the structure in question is not too close to the ocean.

Along the coastline, a C5 (very high corrosion rate) can be expected due to higher chloride deposition rates. Concentration of sea salt aerosols, which are the main atmospheric pollutants in coastal regions, gives an indication of the probability of the atmospheric corrosion.  A combination of the results with a geo-statistical approach and modeling will be used to construct the corrosion map.  Specific environmental conditions, which are affecting the source and distribution of airborne salinity, will also be considered in the construction of corrosion risk maps.

The construction of atmospheric corrosion risk map consists of two phases:

  • In Phase I, the relevant data will be collected, categorized, and analyzed with respect to the project objectives. The information will consist of several distinctive sets of data such as chloride deposition rates, sulfate deposition rates, time of wetness and wind data.
  • In Phase II, a knowledge-based approach along with adequate and accurate equipment, and advanced techniques, will be used to collect, analyze, and verify the Phase I corrosion mapping at statistically representative selected sites. Matergenics recommends that investigators should not only consider atmospheric parameters, but also corrosion sources – such as presence of chemical plants emitting corrosive gases, electric generation plants, salt sprays sources, wind loads… – in order to determine and comprehensively assess corrosion risks.

A proprietary method is utilized in Matergenics’ corrosion risk assessment. The method includes an algorithm to assign a corrosivity index to each location on the map based on atmospheric data, wind  data, and  corrosive gases by chemical plants.  The accuracy of this algorithm has been field tested and proven in several projects in California for major Utility companies.

Case Study

Recently we were retained by a major electric utility company to assist them in developing a corrosion risk assessment map for their service territory.  The genesis of this project started when they found severe below-ground corrosion on several steel structures after a short time in service.  Considering that they had several thousand structures across their service territory, the thought of inspecting each and every one of the structures would be a monumental as well as a costly task.  In consulting with Matergenics it was decided that the best way to approach this would be to develop a corrosion risk assessment map of their service territory.  The map would identify areas of high, medium and low below-ground corrosion risks. As part of this project, we performed carefully selected field inspections in each of the various risk areas.  The data was then used to confirm the accuracy of the corrosion risk assessment map.  Once the map was completed our customers were able to concentrate their resources on structures located in high corrosion risk areas.  The mapping effort has been completed and we have provided the client with a map in ArcGIS which they will put into their GIS system.  Customers are using the map for many things (operation, maintenance, geotechnical) with regards to other steel corrosion efforts.

 

                                   Localized Corrosion Due to Stray Current. Corrosion Map Application

We also provide the following services:

* GIS Corrosion Mapping and Drone Inspection and Thermographic Imaging for Pole/Tower Condition Assessment
* Paint Coating Selection for Above Ground and Underground Applications
* Custom-designed cathodic protection systems with deep well design for tower facilities
* Remaining Life Modeling and Estimation for Underground Assets
* Monopole Fatigue, Fatigue Sensor and Fatigue Mitigation
* Why stray current is an important issue in corrosion and How to detect it?
* Corrosion Engineering Training

Our condition assessment considers:

  • High Elevation Atmospheric Corrosion
  • Low Elevation Atmospheric Corrosion
  • Ground Level
  • Shallow Burials
  • Deep Burials due to low pH (not considered by many)
  • Concrete Degradation
  • Coating Degradation
  • Stray Current Corrosion
  • Copper Grounding

Condition Assessment By Climbing Inspection

Inspection Overview and Procedures

The overall condition of the tower structural members, climbing facilities, fasteners, and other components are evaluated as outlined in this section. Visual and physical checks are performed to ensure that the tower and subsystems are structurally sound and functional.

Tower load bearing members , conduits, ladders, stairways. fasteners, and all load bering primary and secondary members will be checked, documented and severity of corrosion will be reported by our experienced climbers and NACE certified corrosion engineers. Corrosion mitigation: coating selection, surface preparation and application of coating per SSPC and NACE specifications will be provided for the Client’s review.

Physical inspections and UV thickness measurements  are performed  to determine steel member thickness using Ultrasonic Thickness Gauge. All corners of the towers are checked at the ground level and at any location that appears questionable with a three-point check that covers the leg and the braces on either side of it Coating thickness is also checked at these points using an Elcometer 456 Coating Thickness Gauge. ASTM A-123A is referenced for coating thickness requirements. Galvanized Thickness and protective organic coatings are measured as well.

Concrete foundations and anchoring hardware are visually checked for wear and damage.Concrete hardness tests are performed using  Digital Concrete Test Hammer. Two hardness measurements are taken per foundation corner – one set of four readings on the top of the foundation (vertical reading) and one set of four readings on the side (horizontal reading).

MATERGENICS provides corrosion inspection/monitoring services, and corrosion risk assessment for different types of telecom structures including:

  • Guyed-wire towers,
  • Self-supporting towers,
  • Tapered steel monopols.

If corrosion is not detected and mitigated at its early stages, shortly it will lead to expensive refurbishment of corroded members, while in a longer time it can affect tower safety and increased risk for injuries, and fatalities. Periodic corrosion inspection and risk assessment is a cost-effective method to bring certainty to core asset safety. Team Matergenics can assist you on these tasks. At your request we can provide a comprehensive.  presentation on our approach and experience in this important field

We can assist you with the following important tasks:

  1. Construct soil corrosivity maps for  sites for system-wide corrosion risk assessment and maintenance
  2. Prioritize towers for corrosion risk assessment based on corrosion map, age, design/material, tower criticality, consequence of failure (high consequence areas- HCA)
  3. Evaluate existing aging assets (based on prioritization order) and assess corrosion damage in high elevations, low elevations, ground level, and underground and for guy wires through visual examination, drone inspection and NDT techniques
  4. Perform indirect assessment of towers, and galvanize anchors
  5. Perform condition assessment of concrete foundations by inspection and petrographic analysis
  6. Perform direct assessment (excavation/climbing and focus measurements)
  7. Measure grounding resistance and document grounding components
  8. Evaluate tower coating systems and select coating for various environments
  9. Perform failure analysis root cause determination for accidents and incidents
  10. Determine acceptable or unacceptable risks and provide engineering solutions for risk mitigation
  11. Engineering solution for material selection, coating, cathodic protection, structural repairs
  12. Sensor development and corrosion activity monitoring
  13. Post assessment and development of tailored inspection program for long-term cost-effective corrosion mitigation and maintenance

Why Matergenics

Team Matergenics is able to provide many unique services to assess the corrosion risk and to determine the remaining life of towers and anchors. We are also able to provide best-in-class CP design for helical anchors and special situations where installation of galvanic anodes is not feasible. What distinguishes us from our competition are the following:

  • We are trained, academic-disciplined corrosion engineers and we have four top level certifications from NACE; our competition does not have high-level corrosion certifications
  • We have successfully completed thousands of corrosion assessments projects for telecom structures to predict and quantify the corrosion rate and determine their remaining in-service life
  • We have developed patent pending GIS soil corrosivity mapping for corrosion risk assessment as a system-wide maintenance tool
  • We can provide computer-aided anode bed designs for optimum cathodic protection at tower foundations―we are NACE-Certified Cathodic Protection Specialists (CP4)
  • Every year we perform thousands of inspections on transmission lines and communication tower foundations buried in corrosive soils, identifying deep burial corrosion where competition is unable―thickness measurements at shallow burial is not necessarily representative of the integrity of the structure
  • We have a modern materials and soil testing laboratory and can perform failure analysis root cause investigation for different modes of failures at tower component
  • We have published many technical papers that have been reviewed and cited by experts in corrosion field (most recently regarding galvanized anchors, which is attached for your review)
  • We have repeat clients and can provide references form SBA Communications, Crown Castle, Southern California Edison, Consumer Energy, Valmont Industries, to name a few
  • Our corrosion risk assessment includes grounding evaluation, concrete inspection, and petrographic analysis
  • We understand budget limitations and can provide options to fit your budget if you wish

Items 1, 3, 4, 5 and 6 are unique to team Matergenics and we do not know of any other firm performing these tasks. Please see the onsite photos attached to this document for examples of our work.

INSPECTION STAGES

MATERGENICS’ corrosion inspection for telecom structure, involves three different stages:

Desk Study

Prior to site visits and field measurements, based on the project requirements, a desk study must performed to complete the following tasks:

  • Review of geotechnical reports,
  • Review of structural drawings,
  • Review of previous reports on corrosion inspection, maintenance/repair, and all other relevant information including service history.

Field Survey

Our NACE certified inspectors collect the key corrosion indicator data at tower base and anchor footings, and perform site-specific tests to characterize the service environment, including:

  • Soil-to-structure electrochemical potential mapping,
  • Soil resistivity tests (ASTM G57 and ASTM G187),
  • Soil pH tests,
  • Cathodic protection current requirement tests,
  • Visual inspection of underground members,
  • Coating inspection and dimensional measurements,
  • Concrete inspection and hardness test (ASTM C805),
  • Photographic documentation of all tests.


Laboratory Investigations

Collected samples during site visits must be examined in a controlled environment to identify:

  • Soil contamination concentration,
  • Microbiologically induced corrosion,
  • Root cause determination.

Documentation & Reporting

All inspection findings and recommendations are included in a comprehensive report, that includes:

  • Corrosion risk factor (CRF) for individual structures,
  • Recommend corrosion mitigation methods such as cathodic protection,
  • Remedial actions,

Engineering analysis and repair recommendations.

Cathodic Protection

Matergenics is able to design, install, test, and monitor cathodic protection systems that prevent any further corrosion and extend the life of buried assets for at least 15 years. Compared to oil and gas industry, the tower industry as a whole is behind on implementation of CP method of extending in-service life of the assets. The oil and gas pipeline industry has been using this method successfully for many years to prevent failures and reduce inspection and maintenance costs.

PhD-level NACE-certified engineers in Matergenics have developed an advance simulation tool to design best-in-class anode bed designs for optimum protection of tower foundation regardless of structural materials and designs.

 

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Related Services


 

We design and Install Cathodic Protection Systems for Tel-communication Towers Based on Corrosion Engineering Principles and By NACE Certified Technical Personnel.

We understand budget limitations and can provide options to fit your budget if you wish.

Coating Selection for Atmospheric, Ground Level  and Underground Zones

Another effective way to protect structures against corrosion attack is to use a coating film to shield it from the environment. However, not all coatings are created equally. Matergenics has several coating experts that are equipped to test and analyze coating quality based on common coating failure modes.

 

Proper coating system and Adequate surface preparation per SSPC and NACE standards are extremely important for atmospheric high elevation zones of the telecom tower. To improve the protection level at foundations of telecommunication structures, Matergenics recommends partial coating application along with CP system installation. This results in improved protection at both deep and shallow burials, also extends the lifespan of anodes. Answers to the following questions are keys for a successful coating application:

  • Coating material – was the coating material suitable for the service environment and the substrate?
  • Surface preparation – was the surface properly prepared to allow for coating adhesion?
  • Application – was the coating applied using proper technique at the correct thickness?
  • Formulation – were the drying and curing specifications followed?
  • Mechanical damage – is the coating susceptible to damage backfilling
  • Cathodic protection shielding – is the coating compatible with cathodic protection?

ASTM, SSPC, and NACE test procedures are followed to assure that the selected coating will survive and protect the structure as intended. These tests include:

  • Accelerated paint exposure
  • Salt spray
  • UV light exposure
  • Tensile and flexural tests
  • Cross section microscopy

Considering our expertise, Matergenics is the only company that can select coatings that work with cathodic protection systems to guarantee maximum protection to extend the life of any structure.

WE VALUE OUR CLIENTS

We are here to help. We respond to all customers promptly by sending a technical proposal to address testing, investigation and the proposal costs. Please call Dr. Zee at 412-952-9441  or Matergenics at 412-788-1263 and let us know how we can assist you..

Looking forward to hearing from you!

 

 

 

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