ETI is a pioneer in the technological advancement of ILI tools. In its MFL tools, it introduced the use of Hall effect sensors, solid state memory and multi-axis sensors. More recently, it has implemented Extra High Resolution (XHR) principles and data analysis. It samples the magnetic leakage field from two to four times as frequent as most other tools. ETI has strengthened the definition of XHR data to include data reduction parameters consistent with this higher accuracy in field mapping and introduced new proprietary technology that provides three-dimensional data analysis without the use of multi-axis sensors.

ETI has specialized equipment for the inspection of large diameter water lines. These tools are available for lines from 48” diameter up to 120” diameter and can be used in mortar-lined pipe. ETI can inspect pipelines outside of this range if required.

ETI provides reliable state-of-the-art In-Line Inspection tools (ILI) for the water industry. Each tool is equipped with:

  • Extra High Resolution (XHR) Magnetic Flux Leakage (MFL) (XHR MFL)
  • Combined geometry sensors
  • Uniform sensor spacing
  • 1.5D bend capability
  • 25% bore reduction capability

Tool Specifications



All large-diameter, cement mortar-lined steel pipes are candidates for inspection by ETI’s extra high resolution MFL inspection tools:

  • Water distribution and main inspection
  • Water utilities and authorities

ETI can also run the tool in non-coated pipelines and can inspect the pipeline for ovality, dents and wrinkles in the pipeline. Typically, this “geometry run” is performed prior to the MFL inspection run.

The Magnetic Flux Leakage (MFL) tool is delivered to the site of the inspection in component parts designed to fit through a manhole as small as a 14-inch by 16-inch oval. The process begins once the pipeline is taken out of service and drained. On completion of specific confined space training, the field crew enters the pipeline and assembles the component parts of the tool as they are passed through the manhole.

Assembly begins by joining three full sections together to form the bottom of the tool. The field crew then assembles the inner ring of the tool. The inner ring does not have the full sections assembled yet, as to allow the field crew access to the inner ring for attaching the magnetic sections. Magnetic sections consist of the magnets and a backing bar to create a type of “horseshoe” magnet. The sensor heads are located between the two magnets and on top of the backing bar so that the sensor head sits inside the magnetic field and records variations in the magnetic field during the inspection. The magnetic sections are positioned on the pipe wall and attached to the inner ring of the tool to maintain proper spacing of the sensor heads around the circumference of the pipe. Once the magnetic sections are attached to the partially assembled tool, the remaining components of the tool sections are attached to the inner ring and joined together to form the complete tool.

Once the tool is fully assembled the electronic components are installed. The cables from the sensor heads are installed in a module that distributes power to each sensor head, provides a ground for the sensor heads, and has data lines which issue commands to the sensor heads from the main computer board of the tool. The data collected by each sensor head is stored on the memory chip installed in the module. The modules are “daisy chained” together to allow for the uniform distribution of power and communications between the master board and each individual sensor head. Once all the sensors head cables are plugged into a module and all modules are included in a daisy chain, the battery canister is installed. The terminal ends of each daisy chain are plugged into the battery canister. The battery canister also has the master computer board installed in it. The master computer controls all the power distribution to the sensor heads and issues the commands for each time a sensor is to take a reading of the magnetic field strength. The completed tool is shown in Figure 1a

Electric Tow Vehicles (ETV)

Two Electric Tow Vehicles (ETV), attached to the front and back of the tool, are used to move the tool through the evacuated pipeline. ETV components, like the MFL tool, are designed to fit through an ingress point as small as a 14-inch by 16-inch oval. Components are handed down piece by piece to the field crew working inside the pipeline and assembled at the same time as the MFL tool. An assembled ETV is shown in Figure 1b.

The time to complete an inspection is dependent upon the length and physical characteristics of the line to be inspected. ETVs are typically fully assembled in a few hours while the MFL tool takes approximately 1½ to 2 days to fully assemble. The tool can travel up to 5 miles per day. Disassembly of the MFL tool and ETVs are done at the same time and can be accomplished in four to five hours. To achieve best performance onsite, ETI requires adequate lead time to ensure the tool is working correctly and all necessary parts are packed before the tool is transported to the job site.

Figure 2 pictures the tool inside the pipeline, which had been opened by the Client by cutting a “half cap” at this point for a specific one time only purpose not related to the tool. The tool is designed with a cavity through the middle of the tool that allows people emergency egress through the tool should it be required.


Once an inspection run is complete, a field technician downloads data directly from the tool’s data modules to a laptop hard drive via an ethernet connection located in the battery canister. The data remains in the tool’s module’s memory until it is specifically deleted by a user, which usually occurs after the inspection has been completed and the data analysts verify they have all the data from the data modules.

Data is then transmitted to ETI’s office in Salt Lake City for analysis by an Analyst. The Analyst takes the raw data from the tool and converts it to a viewable format then interprets the results to complete the analysis and prepare a report on the findings. The converted data looks like a line, but it is in fact made up of a series of points which are the recording of the voltage levels of each sensor when the sensor took a measurement. Each line is one sensor and all the lines together represent the circumference of the pipe. When a defect is present the magnetic field within the pipe wall “leaks” out and the magnetic field outside of the pipe wall increases in strength which in turn creates a higher voltage reading in each sensor. As shown in Figure 3, the lines curve up and then back down to the “nominal” position at a defect. The Analyst then can determine the length and width of the defect and based upon the voltage readings give a very good estimate of the depth of the defect through the pipe wall.

Corrosion Results (Actuals)

The data shown in Figure 4 below is from an actual run and was located by the tool in an area in which the client was unaware of any issues. As can be seen there is wide spread corrosion in the pipeline at this location. The corrosion was located at the bottom of the pipeline. When the client excavated the area to inspect the pipeline they found that the top of the outside mortar coating had cracked, and water was leaking into the area between the mortar coating and the pipe wall. The water then settled at the bottom of the pipe and corroded the pipe wall. The section of pipe was removed and replaced. This saved the client an unplanned outage of the pipeline due to a failure of the pipe. Knowing the extend of the damage and the location of the damaged pipe allowed the client to plan and take the pipeline out of service without disrupting the customer’s needs


Figure 5.0 below shows the analysis data from an anomaly found during an inspection. The other pictures show the exposed pipe, and the measurements of the damaged section. This damage (gouge) was likely caused by a plough and was unknown to the client prior to the inspection. Further, the client never thought that this type of damage would occur to the pipeline.

Sample Report