SOIL CORROSIVITY & CORROSION RATE DETERMINATION
Matergenics – Pittsburgh has created a specialized market in soil corrosivity, corrosion risk assessment and identification of corrosive hot-spots for underground assets and infrastructure that is not considered by traditional Close Interval Surveys (CIS) and circumvent functioning cathodic protection (CP)
Field and Laboratory Soil Analysis Capability
Knowing the corrosion rate of a metallic material is critical to determine the remaining life of underground structures. It also helps to understand whether or not mitigation, coating or cathodic protection is required.
We at Matergenics are not only able to determine the corrosion, but we also have the expertise to provide you with corrosion rate and a recommendation that is specific to your specific application.
Predictive models for pit growth and material loss have been developed for underground ferrous materials (Pipeline, Tanks, T&D and Galvanized Anchors) based on statistical analysis on collected data obtained from:
- Surveys of the condition of buried structures
- Scientific exposure of buried materials
- Sensor-based studies or monitoring of buried materials and coupons
Dedicated Soil Lab
The combination of field and lab analysis provides essential data for geotechnical, asset management, site surveys, CP installations, and failure analysis
Field and Laboratory Soil Analysis Capability
In early studies, the NBS data were used to estimate corrosion performance parameters for different soil types. Forty- seven (47) NBS soil sites were divided into 4 groups based on aeration level, ranging from well-aerated sands to poorly aerated tidal marshes.
From a practical point of view, it is desired to relate regression model parameters to measurable physiochemical properties of soils. To address this, different sets of coefficients and modified forms of the regression model are proposed by several researchers based on NBS data and other similar experiments. In Matergenics’ predictive model a wide range of corrosion parameters are involved such as:
SULFATE ION CONTENT |
CHLORIDE ION CONTENT |
|---|---|
CARBONATES & BICARBONATES |
REDOX POTENTIAL |
PH OF SOILS |
SOIL RESISTIVITY |
SULFIDE ION |
MOISTURE CONTENT |
BUFFERING CAPACITY |
INSTANTANEOUS CORROSION RATE |
ELECTROCHEMICAL TESTING |
Matergenics have reviewed, all available predictive models and the most relevant regression coefficients are used to predict the corrosion rate for the client’s assets in given soils based on the corrosion performance parameters (above data).
Two other labs agreed to do some analysis, but Matergenics came through and provided us with exactly the results we needed.
Predictive Models for Corrosion Penetration and Pitting
This Unique approach is what distinguishes us from our competition.
The following criteria are used for the recommended predictive models:
- Validation against short term and long term corrosion data
- Dependency of model parameters to relevant physiochemical properties
Using our unique algorithms developed by expert corrosion engineers, the soil around a buried metallic asset is assigned a soil corrosivity (SC) rating that is based on a number of parameters including soil resistivity, pH, chlorides, sulfates, and linear resistance polarization corrosion data, These ratings identify high soil corosivity areas where assets are located and, based on these ratings, decisions for inspection frequency, prioritization, and long term planning can be made with confidence.
Based on chemical analysis and corrosion performance parameters of the soil we are able to predict the corrosion rate and pitting in the given soil. Life expectancy and remaining life is predictable in corrosive soils by our predictive model that is based on field evaluations and laboratory testing of soil.
Accurate Predictive models
Our model is based on many thousands of field data and findings and predicts corrosion penetration with moderate to high certainty
Soil testing
| Determination | Soil Corrosion Performance Parameters | Comments |
|---|---|---|
| Simple Soil Chemistry | pH, Resistivity, Chlorides, Sulfate, Sulfide, Moisture, Redox Potential | Based on ASTM Techniques |
| Corrosion rate based on LPR/ER for: Steel, Zinc, SS Cu in given soil | Mils /year (mpy) Instantaneous Corrosion Rate | Based on ASTM G96 |
| MIC Study | SRB, APB,… | Total Bacteria, SRB, APB, IOB,.. |
| Predictive Modeling | Long Term Corrosion Behavior of the Asset and Corrosion Mitigation Recommendation | Provides corrosion penetration as a function of time (long term,10, 20, 30, ..50 years) |
Standard Soil Tests by Matergenics
- AASHTO T290: Sulfate Ion Content in Soil
- AASHTO T291: Chloride Ion Content in Soil
- ASTM C1580: Sulfate Ion Content in Soil A
- STM D1498: Redox Potential of Water A
- STM D2216: Moisture Content of Soil
- ASTM D2487: Soil Classification
- ASTM D421: Dry Prep SOIL SAMPLES
- ASTM D4318: Liquid Limit, Plastic Limit, Plastic Index of Soils
- ASTM D422: Particle Size Analysis of Soils
- ASTM D4972: pH of Soils
- ASTM G102: Corrosion Rate
- ASTM G51: pH of Soil for Corrosion
- ASTM G57: Soil Resistivity
- ASTM D4658: Sulfide Ion in Water
- ASTM G162: Conducting and Evaluating Lab Soil Corrosion Tests
- ASTM D512: Chloride Ion in Water
- MIC Tests
In summary, we can determine soil chemistry, estimate soil corrosivity, quantify corrosion risk, predict the corrosion rate and life expectancy of given underground asset based on chemistry of a soil environment it is exposed to. Having this data will enable you to predict the remaining life and if you must install cathodic protection system to maintain your assets.
