According to an adapted Murphy's Law, 'anything that can fail, will fail.' While that universal engineering law has been proven true again and again, many utilities are working diligently to reduce the risk of failure by taking measures to improve the service life of their aging metallic assets.
In North America, with the majority of water infrastructure reaching the end of its design life, operators have every incentive to take a proactive approach to pipeline management. Nowhere is this more critical than in busy urban centres, where transmission mains frequently run beneath city streets, posing a greater risk and a bigger challenge to water utilities.
In a downtown core, unexpected failure can escalate repair costs and cause major disruptions to business and commuters. An urban geyser from a ruptured pipe or even a hydrant can easily diminish public confidence in the utility and reputations will suffer.
Historically, there have been few non-destructive methods to assess the condition of metallic pipelines, forcing utilities to operate these critical assets to failure. Complete replacement is not only unfeasible, but wasteful, since the majority of pipelines have remaining useful life.
To help operators defensively address their pipeline conditions, Pure Technologies provides a suite of tools, technologies and engineering analysis programs that allow for a comprehensive condition assessment of metallic pipelines.
Magnetic Flux Leakage is the standard for high-resolution metallic pipe assessment
In general, the condition of metal pipe is typically first assessed with leak detection technology and a detailed pipe wall assessment (PWA) screening.
Once PurePWA identifies pipe sections with increased levels of stress, the data can be verified with Magnetic Flux Leakage (MFL), recognized as the industry standard in high-resolution metallic pipe assessment. MFL is the most accurate testing method that identifies pitting and wall loss on steel and ductile iron pipes, which makes this testing method and extra-high resolution appropriate for high risk, critical-location pipes.
How MFL works
With PureMFL technology, powerful magnets are attached to one of Pure's three platform tools â€“ manned, pig or handheld. The magnets saturate the metal pipe wall with a temporary magnetic field, while sensors record variations of the magnetic field around any pipe wall defects. Where a defect exists, there is a disruption in the field causing some of the magnetics to 'leak' out of the pipe wall.
The data collected with the MFL tool is then correlated to a location along the pipeline using multiple techniques. There are three odometers built into the tool for linear distance integration, inertial sensors for motion integration and pipeline feature correlation.
PureMFL data identifies defects as small as 0.25 inches in diameter and 10 percent wall loss, which explains why the technology is regarded as the most accurate in the pipeline testing industry. In addition to locating and quantifying the extent of corrosion in metal pipes, PureMFL technology is also able to identify different liners such as mortar and coal tar.
Utility uses PureMFL technology to confirm PWA data on critical pipes
In one specific case, a medium-sized utility in the Carolinas decided to take a proactive approach to assess and manage the condition of one of its critical 12-inch force mains. The utility began its screening assessment using Pure's SmartBallâ„¢ tool, an inline leak and gas pocket detection platform paired with pipe wall assessment technology in a single deployment.
After completion of the SmartBall assessment, several gas pockets and stress anomalies were identified. From the PWA data, two pipe selected for validation were identified as anomalous, and showing significant stress indicators, while a third pipe with no stress indicators was used to determine a baseline for comparison.
In response, the utility exposed these pipes for testing, and Pure's crew deployed its state-of-the-art MFL external scanning tool to generate a high resolution profile for each of the two distressed pipes. The MFL testing found moderate to significant wall loss on the pipe sections identified as anomalous through PWA analysis.
Overall, the investigation will provide the utility with actionable information that can be used to plan a repair and replacement program for their critical pipeline, and assist in preventing future Murphy Law failures.