Detection of pipeline movement made as effortless as cleaning

Authors: Michael Schorr and Beatrice Haring, ROSEN, Germany

For the detection of geohazard-induced bending strain and pipeline movement, an inertial measurement unit (IMU) has proven itself to be an indispensable component of pipeline integrity. Operators whose pipelines are vulnerable to geohazards like shifting debris, landslides, erosion, washouts or free spans, need to identify stresses promptly following such an event as bending strain and pipeline movement can cause their pipelines to fail.

IMUs are typically integrated into combined technology in-line inspections by utilizing corrosion or crack detection systems and geometric calipers. While these technologies can provide additional relevant information on the threat situation, these more complex tool runs require more resources than a simple IMU unit and have longer lead times – resulting in high costs. The RoGeo PD service combines an IMU with a standard cleaning tool, which allows an operator to successfully mobilize and deploy an IMU with significantly less effort, thus reducing cost and resources required to complete an inspection.

Figure 1: 20” (508 mm) Cleaning pig with pipedrift probe for the detection of bending strains

During a recent collaboration with a major North American operator, ROSEN has proven the technology and approach as feasible and reliable on several pipeline segments with a significant number of previous IMU inspections that utilized more conventional combination technology platforms. A number of these pipeline segments had verified areas of pipeline movement that served as appropriate case studies, two of which can be found below. In these comparisons the PipeDrift (PD) IMU approach and extended caliper (XT) were compared as well as the PD between themselves:

Figure 2: Summary of PD and XT combination pipeline movement results

The bending strain signals produced by the XT and PD technology are particularly notable. The similarities of their signal responses to smaller influences such as girth weld jumps or pipe segments that produce signals containing more “noise” indicate that properly aligned datasets produced by dedicated IMU platforms are as accurate as those of a standard combination tool.

Figure 3: Run 1, Line A. Bending Strain comparison for pipeline movement area 1

The primary objective of these deployments was to determine the feasibility and efficacy of the technology and assessment process when applied to geohazard detection. Upon completion, the accuracy and reliability of the dedicated IMU was confirmed and improvements were made to the assessment methodologies.

The datasets indicate alignment and repeatability when compared to both proven technologies and other PipeDrift inspections. IMU data quality remained high with average run velocities of up to 6.9 m/s and we believe that even higher velocities are achievable.

In conclusion, the RoGeo PipeDrift service provides a cost-efficient approach with an extremely short turn-around time, enabling pipeline operators to implement a screening process, identifying any movement related hazard to their asset integrity.