Netherlands Eneco conducts hot water Pipeline inspection with SmartBall™ tool
Would you take on a new pipeline inspection challenge, even if you knew it would land you in hot water?
Recently Pure Technologies (Pure) was able to chalk up success by adding one more type of pipeline to its inspection resumé. In this instance it was a district heating pipeline owned and operated by Eneco, one of the largest producers and suppliers of natural gas, electricity and heat, serving more than two million business and residential customers in the Netherlands.
District heating make sustainable sense
The concept of heat pipelines makes a lot of environmental sense. Throughout northern Europe, many municipalities and power generators have built closed systems of vacuum-insulated pipelines that circulate hot water from power plants and incinerators, sometimes above 100°C, through radiators in houses, businesses and other structures. This is an efficient method of heating buildings, and boasts a 98 percent heat retention rate during transmission.
Pure performs SmartBall leak and gas pocket detection survey
Recently Eneco contracted Pure to perform a comprehensive SmartBall® leak and gas pocket detection survey of the Centrale Merwedekanaal to WOS District Heating System. This is a 500 mm steel pipeline within a 700 mm steel pipeline of which a vacuum is created in the annular space to insulate the hot water. The survey purpose was to locate leaks and pockets of trapped gas present in the pipeline at the time of inspection.
The subject pipeline, originally installed in 1985, was suspected of having a leak, owning to an observation of water present in the annular space. As mentioned, the heating system pipeline consists of an inner 500 mm steel pipeline and an outer 700 mm steel pipeline, with a vacuum maintained in-between. The lines, constructed both above ground and below ground, incorporate numerous 90 degree bends and u-shapes, to allow for expansion and contraction as the product temperature changes.
During the project, Pure inspected approximately 2.6 kilometers of the pipeline, with the goal to locate the leak(s) causing the water loss.
For the survey, Pure proposed the SmartBall leak and gas pocket detection system, a free-swimming, acoustic-based technology that detects anomalous acoustic activity associated with leaks or gas pockets in pressurized pipelines.
While other leak detection techniques such as noise loggers and correlators may identify a single leak or gas pocket between each sensor, they cannot accurately locate the limits of an anomaly nor identify multiple anomalies. In this specific case, the use of noise loggers is hindered by isolation. The SmartBall tool travels directly past each acoustic anomaly of interest on the inner pipe and thus significant advantages are recognized.
Unique challenges to overcome
The standard procedure for tracking the SmartBall tool depends on positioning acoustic sensors on the outside of the inspected pipe and listening to the device as it passes.
Since the line is so well insulated from heat loss, it is also well insulated against sound transfer, which meant it unlikely for good tracking on any sensor mounted to the outer 700 mm pipe. Additionally, Eneco was understandably averse to compromising the integrity of the vacuum seal of the line, and therefore did not wish to expose the 500 mm pipe to mount sensors.
In the absence of external tracking means, other reference points in the data are critical for accurately locating anomalies within the pipeline. SmartBall contains gyroscopes that can measure bends in the pipeline that it traverses, and as there were many aforementioned 90 degree bends, these were clearly seen in the data. The bends in the Eneco pipeline made for great geospatial reference points and therefore allowed for locating anomalies with relatively high confidence.
SmartBall tool deployed to survey district heating pipeline
The acoustic data recorded by the SmartBall tool was analyzed and cross-referenced with the position data. From the data collected and analyzed, the SmartBall device detected five (5) possible weaknesses, which were clearly visible in the data. Zero (0) gas pockets were detected.
The results give Eneco actionable data regarding the condition of their pipeline, and despite challenges, the assessment is proving its worth. It’s a great example of a proactive utility taking efforts to maximize its capital expenditures.