Water Main & Pipeline Inspection Services

MATCO Services has years of experience in all aspects of on-site and laboratory inspection of  and assessment of water mains and pipelines. Our team includes Ph.D.s, registered professional engineers, and certified inspectors from a variety of technical disciplines, including pipeline  engineering, corrosion, mechanical engineering, coating inspection, chemistry, metallurgy and materials science. We also have a comprehensive array of laboratory and field testing equipment, all calibrated on a routine basis in accordance with both national and international standards. This team is ready to be put to use at a moment's notice.

Corrosion on pipelines is directly related to the internal and external (soil) and Graphitization (for cast Iron Water Mains) conditions present for the unique location of a given pipeline, as well as to the materials of manufacturing and the quality of these materials. Pipelines in submerged conditions are subject to a greater risk of corrosion because of the continuous presence of corrosive moisture – the electrolyte necessary to have the electrochemical corrosion reaction proceed. The specific chemical composition, resistivity and redox potential of the soil/water table will determine the relative corrosivity or risk of corrosion.

In addition to the soil characteristics, it is useful to measure the electrochemical potential of the structure in the electrolyte (soil or water). This is done using methodologies developed by the underground pipeline industry and recognized by NACE International and other professional societies and regulatory organizations. The structure-to-soil potential of a buried asset can be related to the present state of corrosion, with less electronegative values of potential indicated an increasing likelihood of active corrosion. By using sacrificial (galvanic) cathodic protection or impressed cathodic protection system, corrosion can be mitigated by shifting the structure-to-soil potential to more electronegative values( 0.85 Volts vs  Cu/CuSO4 ) where the corrosion reactions are not favored thermodynamically.

A site investigation includes partial excavation for visual and NDT assessment of the underground water main or structure and nondestructive evaluation of graphitization in cast iron water mains. The NDT testing and visual observation complements the non-invasive structure-to-soil potential evaluation and, in the instances of active corrosion, allows direct assessment of the state of corrosion . It also allows for visual observation of mechanical damage  and the condition of protective coatings at and below the ground line. If sufficient material loss has occurred to compromise the design strength of the water main or pipeline, replacement of the components may be required.

Graphitization of A Cast Iron Main

MATCO's extensive experience with  graphatized water mains provides specific  knowledge and know-how  that can evaluate gray cast iron water mains  from the graphitization point of view, the most common corrosion  failure mechanism  in cast iron water mains. We can evaluate the existing water main , predict its performance , and also recommend repair, cathodic protection  or select a new coating for that specific soil/water table application. This knowledge comes from our experience in evaluation of numerous coated  pipelines in different soil environments and corrosive conditions. This type of evaluation requires both metallurgical and  NDT experience with underground water mains and pipelines. Very few firms have the specific knowledge required to evaluate aged graphatized water mains by non-destructive testing. The first steps in a site investigation include recording the pipeline identification, type, and GPS location. The orientation will be confirmed and recorded before performing any inspection evaluations. The immediate area surrounding the water main must also be examined and documented to look for other structures or buried pipes which may influence the evaluations which are to follow.

Soil resistivity will first be measured and recorded before any soil is disturbed. Structure-to-soil potentials and close interval potential readings will also be measured before soil disturbance.

As excavation proceeds, soil samples should be obtained from the near-surface and bottom of the excavation, or wherever different soil conditions are noted. Soil pH and redox potential should be measured on-site; samples will be procured for off-site analyses of sulfur and chloride content, with enough sample quantity retained for additional evaluations of pH, soil composition or soil resistivity per ASTM G 57 if required or requested at a later time.

Excavation of the buried structure to the required depth should be conducted. Dirt/rust removed should be removed from the structure by brushing and/or washing. Visual assessment may be complemented by holiday testing on coated water mains; paint and  coating thickness measurements may both be required.

The MATCO team has experience working in many other  fields; from design, implementation and monitoring of cathodic protection to coating inspection to failure analysis to remaining life determination. Our tea includes NACE Certified Corrosion / Cathodic Protection/ Materials Selection/ Design / Coating Specialists (*)and other materials experts includes:

Dr. M. Zee (*)                                             Mr. Geoff Rhodes (*)

Dr. Don Gibbon                                          Mr. Kevin Groll  (*)

Dr. Bayer                                                  Ms. Debra Riley (*)

Dr. Huiping Xu                               Mr. Ed Larkin

Mr. Sam Scheinman                                  Mr. Walter Gretz, PE