Below-Grade Corrosion Inspection 

Don't Be Surprised by What You Can't See!

Once thought to be permanent structures free from maintenance and concerns, steel towers, poles, and other steel assets have demonstrated that they do indeed degrade over time as a result of corrosion and mechanical damage.  Instituting an accurate inspection program is the first step in identifying structures in need of repair.


The Inspection Process

  • The above-ground portion of the structure and the surrounding area are visually inspected to ensure the structure is safe to inspect further
  • The structure is excavated to a depth of 18 to 24 inches
  • The surface of the steel is cleaned with hand tools 
  • Legs/footings/foundation/grillage are inspected for corrosion and other damage
  • Environmental site data including soil conditions are collected and recorded

                  - Soil pH
                  - Soil REDOX 
                  - Soil Resistivity
                  - Half-Cell Potential

  • Relevant structural data including physical measurements are collected and recorded to help determine section loss
  • Each tower is assigned a structural rating (A, B, C, D) and placed in a corrosion category (Very Low, Mild, Moderate, Severe)


Comprehensive Inspections vs. Partial Predictive Inspections

During a comprehensive inspection, each structure is excavated to a depth of 18 to 24 inches.  This is the ideal inspection method for obtaining the most accurate information.  Predictive inspections provide a faster, less expensive approach that allows asset owners to locate "the worst of the worst."  During a partial inspection, only one leg or a portion of each pole or anchor is excavated to a depth of 18 to 24 inches.  Based on the findings in that area (including structural condition and the presence of corrosion or the presence of corrosive factors), a prediction is made as to the condition of the tower or pole.

Non-Destructive Evaluation (NDE) with ITF Intellipole

ITF Intellipole is an improved variation of EMAT ultrasound technology designed to help identify structural defects along the conductive surface of metal structures and determine the extent of defects in conductors, steel poles, stub angles and guy anchors.

This type of NDE is particularly useful for structures that cannot be excavated as well as structures that have been classified as severe and require further evaluation to determine the extent of the corrosion damage.


For more information on below-grade corrosion inspection, please contact Kevin Niles at 716-319-3404 or