Could you do more to ensure that your pipelines are SAFE?
Of course, but is it cost-effective and reliable enough to be feasible? It is if you're using the Spectrum XLI System, a unique survey instrument designed to meet the needs of industry for the “indirect inspection” of pipelines, as part of External Corrosion Direct Assessment (ECDA) programs.
The principle of the system is the automatic detection and logging of the pipeline location using an electromagnetic pipe locator and high accuracy GPS receiver. The XLI system includes a specialized Spectrum Controller that multiplexes the data streams from volt meters (DCVG, ACVG, CP / CIS), Leak Survey Gas detectors, Sonar, and other instruments to allow multiple readings to be logged concurrently.
Depth of Cover / Water Buried pipelines can also become vulnerable to third party damage and UV degradation of the coating when erosion or scouring removes the cover. The Spectrum XLI system can very accurately measure the depth of cover over buried pipelines, and when utilized with sonar and GPS can also provide elevation profiles and depth of water. This allows pipeline operators and engineers to monitor the pipeline and surrounding environment for potentially harmful geotechnical activity, pipeline exposures and erosion of cover that exceeds pipeline code requirements.
ACVG Steel pipelines are laid and buried under land and water, and are subject to corrosion degradation unless they are protected with coatings and or cathodic protection. The AC current attenuation (ACCA) of the XLI electromagnetic field along the length of a pipeline is consistent on pipelines with homogonous coating. Lengths of the pipeline with coating faults will allow larger amounts of the electromagnetic field to return to ground, causing increased attenuations in the field. Measuring the AC voltage gradient (ACVG) between teh soil above the line and a remote soil location allows specific coating faults to be identified and quantified, which the Spectrum XLI system also does automatically. So by measuring and recording the current and AC Voltage Gradient over intervals along the pipeline, coating faults can be identified and prioritized for repair; even before any corrosion pitting has occurred!
Cathodic Protection / CIS The CP DC current applied to the pipeline protects bare metal from corrosion damage, but only if it is able to reach the entire length of the pipeline. By logging close interval CP potentials over the entire pipeline length with the XLI system, the effectiveness of the CP can be determined to aid in prioritization of coating anomalies that may need repair, or to identify required adjustments and modifications to the CP system itself.
DCVG DC voltage gradient surveys can also be conducted to confirm the current direct on and off the pipeline along its length. This survey can aid in identifying and prioritizing coating faults for repair based on the expected corrosion rate as predicted by the current discharge from soil to pipe or vice versa.
Leak Surveys
Leak surveys are logged with the XLI system utilizing state of the art laser methane gas detectors.