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Volume 10 Number 05 - May 2010

REPRINTED FROM

LASER SHARP VALIDATIONS ince it was introduced in 2005, many pipeline operating companies have been

struggling to come to terms with standards like API 1163. The standard calls for constant improvement in pigging results, using both current and historical data to validate tool results. Pigging companies and pipeline operators are finding it very

difficult to confidently validate tool data using current methods of verification. This results in much larger margins of error for the ILI tools and ultimately requires more verification digs in order to confidently validate ILI tool results.

ChallengesOne of the major challenges to accurate tool validation is that when the verification data disagrees with the ILI log data, pipeline operators cannot say for certain where the error

TOM TAYLOR AND DARREN HILL, SMARTPIPE TECHNOLOGIES, CANADA, DESCRIBE HOW PRECISE ILI VALIDATION CAN SAVE PIPELINE OPERATORS TIME AND MONEY IN PIPELINE OPERATIONS.

resides. It may be that the technician located the wrong anomaly or included a large area of superficial corrosion that fell outside the tools detection threshold and were therefore not identified in the log. In reality, the only time that the ILI company and the pipeline operator are inclined to say with absolute certainty that the results have been accurately verified is when the ‘as found data’ agrees with the ILI log. This makes it difficult, if not impossible, to make any valuable refinements that might improve accuracy of a tool.

Pigging companies initially validate their tools in a closed shop environment and establish a margin of error that is

used for their reporting. In order to confirm that a tool is in fact operating within the prescribed parameters, verification digs are conducted. ILI tools have improved a great deal over the last few years but there has not been much progress in operators’ ability to verify the results in the field until recently.

Manual methodsIn a perfect world, a technician, with a variety of measurement instruments at his disposal, would be able to verify with absolute certainty that what the tool ‘saw’ is the same as the actual as found features. This process is quite difficult in truth since the technician has only a spreadsheet identifying the size and location of anomalies and must manually measure the size and location while making allowances for an ILI tools margin of error. When the log identifies individual pitting and this pitting is found within a large patch of general corrosion, it is sometimes extremely difficult to identify these individual features. Once the features have been graded and correlated, it is not possible to go back and look at the area again. This uncertainty leads to an erosion of confidence, which makes it difficult to use the verification results to reliably recalibrate tools or re-grade log results.

Other factors also make accurate validation difficult. Time is always of the essence and with constant pressure to move quickly and save costs on each dig, the technician may not have time to carefully consider the correlation of each feature. Varying levels of training and expertise and the amount of unidentified corrosion or ungraded features all make accurate correlation a very difficult proposition.

SolutionLaser scanning is a very promising technology capable of capturing large areas of corrosion and mapping each feature accurately. Laser scanning delivers a much higher degree of certainty. With rapid capture rates, precise measurements and three-dimensional visual reporting. Laser scanning moves ILI validation from crude art form to a precise science.

A new entrant into this emerging field is SmartPIPE Technologies based in Calgary, Alberta, Canada. It has been field-testing its ProSCAN laser profile scanner for the past two years and recently introduced it at the Houston Pigging and Pipeline Integrity Conference. ProSCAN can be mounted on a pipe of any diameter, with four magnetic wheels that allow it to roll 360˚ around the pipe in order to capture a three-dimensional scan of the pipe’s external features.

Capable of capturing 7800 points/in2, ProSCAN far surpasses any manual methods for level of accuracy. All of the data can then be represented in visual reports that show the exact size and location of all ‘as found’ features. ILI data can be imported and overlaid with scan data to enable accurate correlations (Figure 4). This eliminates the need to attempt correlations in the ditch and to rely on pictures taken in the ditch for verification. The engineering staff now have a high-resolution image of the investigated area, complete with exact size and location of all of the features.

Figure 3. Scan data represented as a 360˚ virtual pipe view.

Figure 2. Laser line captures 7800 points/in2.

Figure 1. ProSCAN Laser Profile Scanner.

Reprinted from May www.worldpipelines.com

Permanent data setOne of the biggest benefits of this method is that it creates a permanent database of every feature ever examined. Now, if there is uncertainty over the accuracy of a correlation result, it is possible to go back to the scans and verify the results. In the past, this uncertainty could not be alleviated except by going back and re-excavating the anomalies. Historical scans can now be used as a baseline to verify any future ILI runs.

Darren Hill, President of SmartPIPE, states that “with the ProSCAN, we are able to capture a high resolution scan with a level of accuracy of 2 mm2, while measuring depths to within 0.1 mm. The real power of the scanner is in our ability to analyse the data after the fact. We can produce a three-dimensional visual report and overlay the ILI data onto it. The result is a highly accurate correlation and a verifiable data set that can be used again and again to validate any tools results now or in the future. Essentially, once anomalies have been scanned and are left in the line, they can be used to validate any future ILI runs.”

ConclusionAs ILI tools improve in their ability to detect and identify anomalies, it is critical that there is progress on the verification side as well. It is encouraging to think that with technologies like the laser scanner, ILI tool results can be validated more easily and with greater certainty. Ultimately, this should result in more effective integrity management programmes that reduce both overall costs and the risk of failures. Figure 5. Scan data can be filtered to match the resolution of the

ILI log.

Figure 4. ILI data (represented as red boxes) is overlaid with scan data.

Reprinted from May www.worldpipelines.com