Encouraging Innovation in Locating and Characterizing Underground Utilities (2009) / Chapter Skim
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Pages 38-50
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38C H A P T E R 5 Utility Characterization TechnologiesIntroduction "Utility characterization" is the determination of a utility's characteristics other than its location. These characteristics include the type of utility, the type of material it is made of, owner, size, age, pressure, voltage, capacity, condition, and usage status, which is to say whether it is inactive, abandoned, out of service, or active.
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39planning and design process for new transportation projects when such data is available and being used. Surface geophysical methods, many similar to or the same as those described in chapter 4, may be effective for some characterizations.
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40systems, this means the pipe's operating pressure, any expected pressure fluctuations, and the pipe's flow capacity and velocity. For gravity systems, the pipe gradient is critical, and it is important to know whether the system is likely to be surcharged at intervals (that is, operate temporarily under pressure)
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41MAGNETIC FLUX LEAKAGE. The magnetic flux leakage (MFL)
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42geographic coordinates of pipeline's route are calculated by establishing GPS control points along the pipeline and then tying the inertial data to these points. This tool can be used in conjunction with the other tools described earlier to more accurately find anomalies in metal loss, cracks, and geometry inspection.
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43nism for this general internal corrosion. ICDA rests on the principle that the electrolyte settles out, or drains, on the inner lower surface of a pipe whenever a certain critical angle of inclination is exceeded for a specific gas flow velocity.
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44diameter steel pipeline carrying high-pressure natural gas may have little in common with the techniques and equipment appropriate for monitoring small-diameter water distribution piping or sewer collection piping. The available financial resources, the risks posed by potential failure, and the pipe materials or configurations make each application quite distinct.
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45coupling for the sonar signal. The internal shape of the waterfilled pipe or the presence of internal debris below the water level may be measured from the reflected signal's time of travel.
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46X-Ray Inspection Where direct access is limited, X-ray techniques have been applied to measure pipe-wall thickness for pipes covered with insulation. The pipe is exposed to radiation from an X-ray or gamma-ray source.
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47tracer elements can also be used, under the right conditions, to track leakage out of or into a pipe network. The use of tracers is typically more labor intensive than smoke testing but gives better and more verifiable results.
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48drawbacks include the increasing complexity and cost of the equipment, which limit the range of contractors available to bid on the work and which require larger-scale jobs to be costeffective, and whether the range of information that can be collected will in fact be used or needed for effective condition assessment. These issues must be determined on a case-bycase basis, but it is expected that multiplatform inspection systems will become more common as the sensor integration becomes more effective and the costs of such systems drop.
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49Testing and inspection of buried pipelines is discussed in Piping Systems and Pipeline ASME Code Simplified (13)
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507. Jaganathan, A., E
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