The importance of accurate asbuilt data for trenchless

The importance of accurate as-built data for trenchless pipe installations Otto Ballintijn Managing Director - Reduct NV Regional Distributor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

If this is what you can see, start worrying about what you can’t © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

The state of As-Built data accuracy today • The accuracy of historical as-built data is primarily determined by the available technology at the time of installation. • For trenched installations, as-built data is typically fairly accurate because you can see the asset • Early triangulation methods • Totalstation • GNSS • For trenchless installations in general, and Horizontal Directional Drilling (HDD) in particular, as-built data is rarely accurate. • Yet the infrastructure installed by trenchless means is as important and critical as the rest of the network and damage to it is usually far more difficult to repair than for trenched infrastructure. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Why do pipeline operators allow this discrepancy? • Today, inertial navigation technology can obtain accurate as-built data of underground pipe assets regardless of the installation method. So why not use it more? © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Why do pipeline operators allow this discrepancy? • Today, inertial navigation technology can obtain accurate as-built data of underground pipe assets regardless of the installation method. So why not use it more? Two primary reasons: 1. Historical practices tend to be difficult to change. 2. Unfamiliarity with the state-of-the-art technologies available for HDD. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor This is the ground level of the terrain, as measured by the HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor This is the drilled curve, again, as measured by the HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Example of an as-built delivered by an HDD contractor Millimeter values © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Deeper analysis of the depth profile values given by the HDD contractor • The table shows that the HDD contractor reports that he has drilled perfectly level (to the millimeter!) for about 15 meters. • Based on our 20 -year experience in mapping HDD’s that is a near impossibility, particularly on such a short HDD. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Deeper analysis of the depth profile values given by the HDD contractor • The table shows that the HDD contractor reports that he has drilled perfectly level (to the millimeter!) for about 15 meters. • Based on our 20 -year experience in mapping HDD’s that is a near impossibility, particularly on such a short HDD. Suspicions: • the millimeter values are the result of a reverse calculation. • the HDD contractor has based his profile on either the as-designed profile or has no reliable steering data at those points so assumed he was drilling level. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Summary of the key flaws in as-builts drawn by the HDD contractors 1. Data of the pipe is referenced to current ground level, not given as a coordinate in the GNS coordinate system used in India. So the as-built is not future proof! © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Summary of the flaws in as-builts drawn by the HDD contractors 1. Data of the pipe is referenced to current ground level, not given as a coordinate in the GNS coordinate system used in India. So the as-built is not future proof! 2. HDD contractors only provide data of the pilot bore, not the client pipe after it is pulled in. Any changes incurred during the pull-back process are not recorded. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Summary of the flaws in as-builts drawn by the HDD contractors 1. Data of the pipe is referenced to current ground level, not given as a coordinate in the GNS coordinate system used in India. So the as-built is not future proof! 2. HDD contractors only provide data of the pilot bore, not the client pipe after it is pulled in. Any changes incurred during the pull-back process are not recorded. 3. Where is the data for the horizontal profile? ? Are we to assume it is perfectly straight? © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Summary of the flaws in as-builts drawn by the HDD contractors 1. Data of the pipe is referenced to current ground level, not given as a coordinate in the GNS coordinate system used in India. So the as-built is not future proof! 2. HDD contractors only provide data of the pilot bore, not the client pipe after it is pulled in. Any changes incurred during the pull-back process are not recorded. 3. Where is the data for the horizontal profile? ? Are we to assume it is perfectly straight? 4. The As-built is drawn by the contractor. That is a serious conflict of interest! © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

How can inertial navigation technology help? © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained Exchangeable centralizers Sensor probe • Inertial measurement probes contain a range of inertial sensors including: • gyroscopes • accelerometers • inclinometers © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained • Together these sensors are used to record the angular changes of the probe’s core axis in: © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained Heading - Heading + • Together these sensors are used to record the angular changes of the probe’s core axis in: • Heading © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained Pitch + Heading Pitch - • Together these sensors are used to record the angular changes of the probe’s core axis in: • Heading • Pitch © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained Pitch + Roll + Heading + Roll - Heading Pitch - • Together these sensors are used to record the angular changes of the probe’s core axis in: • Roll • Heading • Pitch © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Inertial measurement technology explained Pitch + Distance Roll + Heading + Roll - Heading Pitch - • Together these sensors are used to record the angular changes of the probe’s core axis in: • Roll • Heading • Distance • Pitch © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Operational process Data Collection Data Processing Data Transfer to GIS Operational time required per pipeline segment: 1 HOUR © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Let’s get back to our case … © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Comparison of depth profile • Pipe was mapped twice, once in each direction. • Mapping results highly repeatable. • General shape is clearly different. • Vertical offsets between 0. 5 and 1. 2 m. • … and nowhere is the pipe level for 15 meters © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Horizontal profile analysis • HDD contractor provided no data so it is expected to be straight (red line). • Gyro mapping shows a clear ‘bump’ just over halfway. In fact the actual location of the pipe is more than an meter away from the straight line. • The HDD contactor must have realized this because he steered back to the straight line successfully …. but did not report it. • The important point to make is that as pipeline owner, you want to accurately know where your pipe is for management and safety reasons. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

A bonus feature of Gyro Mapping: Bend Radius Analysis • Typically, straight pipes are allowed to bend up to 1000 times its diameter (1000 D rule). • The pipe in the case study had rdiameter of 323 mm. Following the 1000 D rule a minimum radius of 323 m should be observed (black dashed line). • Minimum radius measured is 190 m (red dashed line). • 190 m is equal to about 590 x D, a serious undercut of the typical design specification. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Conclusion • As-built drawings made by the contractor who installed the pipe are at best questionable. • Pipeline operators must change the as-built criteria in their tender documents to ensure • an independent 3 D survey (not just the depth profile) • of the product pipe (not the pilot bore) • with state of the art inertial navigation technology • Post-installation mapping must include a bend radius analysis as this is critical for the long-term safe operation of the pipe. © Reduct – Product information may change without prior notice. For further information visit www. reduct. net

Take no risk, get it mapped! Thank you for your attention Questions are welcome Regional Distributor © Reduct – Product information may change without prior notice. For further information visit www. reduct. net