Reliable and Cost-Effective Means for Inspecting Underground Pipes in Mines

2019

Pawel Gebski, Acuren Group Inc.; DENIS BOUDREAU, www.acuren.com; Ian Moore, Acuren Inc.

The underground service piping systems are critical components of mining operations. The corrosive and abrasive environment causes piping deterioration over time. The practicality of using typical nondestructive testing methods, such as Ultrasonic Testing (UT) or Radiographic Testing (RT), for measuring the remaining pipe wall thickness is limited in the underground environment. The use of a radiographic source with the related exclusion zones or work stoppages (for RT inspections), or the presence of insulation or coating (for UT inspections) can most often make the application of these conventional techniques infeasible.  Acuren has successfully applied Pulsed Eddy Current (PEC) method for evaluating the remaining pipe thickness in mining shafts. PEC is a reliable technology that measures the decay of the magnetic field induced in the material and compares it to a decay curve to get an estimation of the remaining thickness of the pipe. PEC can determine the remaining thickness of a pipe without removing the coating or insulation. It provides accurate readings even through a large corrosion scale buildup. This approach allowed us to overcome the limitations of other methods, while successfully identifying the eroded sections of piping. Depending on the criticality of a particular piping system our results can be utilized in a number of ways that improve safety of the mining operations and the cost-effectiveness of the underground piping maintenance. PEC results can either be used as a preliminary screening method that pinpoints areas requiring a more detailed measurement, or as a “go” or “no go” criteria for replacing a deteriorated section of a pipe. Either way, this approach allows to determine the proper scope of the maintenance and repair work. In this paper a number of case studies, based on the PEC inspections performed by Acuren in mines, are discussed to present the advantages of this approach.

Keywords: Underground piping, corrosion, inspections, reliability, nondestructive testing