Matergenics’ Approach to Soil Analysis
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 Internal Surveys (CIS) and circumvent functioning cathodic protection (CP).
Our dedicated soil lab has rapid turn-around times and is supported by a multidiscipline team of soil specialists, NACE certified materials and corrosion engineers, CP design and installation specialists, coatings specialists, chemists, and certified lab and field technicians. 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
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 recommendation that is specific to your 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:
1) Surveys of the condition of buried structures
2) Scientific exposure of buried materials
3) Sensor-based studies or monitoring of buried materials and coupons
Soil Chemistry and Corrosivity
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 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).
Predictive Models for Corrosion Penetration and Pitting
The following criteria are used for the recommended predictive models:
1) Validation against short term and long term corrosion data
2) 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. This approach is what distinguished us from our competition.