Is there pipeline life after 40 years of non-operational use?
Tethered inline inspection tool helps European city determine condition of steel pipeline unused for more than 4 decades.
Bilbao is an industrial port city in northern Spain, surrounded by famous green mountains. The metropolis, where more than a million people live, is also famous for the Guggenheim Museum Bilbao, the curvy, titanium-clad building that sparked a downtown revitalization when it opened in 1997.
Recently the city’s utility, Bilbao Bizkaia Water Consortium (BBWC), sparked interest in a possible revitalization program for a segment of its pipeline infrastructure that it had inherited. This involved the inspection of an older steel pipeline that had remained non-operational for more than 40 years.
In July 2017, Pipeline Infrastructure, consultant to Bilbao Bizkaia Water Consortium, decided to conduct a non-destructive evaluation of the utility’s Venta-Alta-Ollargan-Etxebarri Pipeline that had been unused since the 1970s. The utility wanted to use Pure Technologies’ tethered Sahara® acoustic platform for a leak and air pocket inspection to determine the current condition of the pipe wall.
Although not planned initially, owing to the effortless inspection of the Venta-Alta-Ollargan-Etxebarri Pipeline, the crews mobilized for an additional Sahara inspection at the Venta Alta Treatment plant, and the following day, a survey on 600 meters of a 500mm diameter reinforced concrete pipeline located in Portugalete. This pipeline traverses under the Bilbao River near the famous Vizcaya suspension bridge.
“We were pleased with the overall Sahara inspections, and all teams collaborated closely to inform us of the tool’s progress. Now that we know the current state of the pipelines, we can optimize our budgets to make better asset management decisions.”
About the Venta-Alta-Ollargan-Etxebarri pipeline.
Once a critical main within the city’s linear network, the Venta-Alta-Ollargan-Etxebarri pipeline had been decommissioned for more than four decades. Constructed of steel, with an interior epoxy coating, the 1200mm diameter pipeline is more 3,000 meters in length.
The Bilbao Bizkaia Water Consortium sought assistance to assess the condition of the pipeline to determine the possibility of its operation again to deliver surplus water during the storm season for use in the generation of electric power at a nearby Hydro plant.
Due to the age of pipeline, and the fact that it was non-operational for over 40 years, BBWC was interested in locating any possible leaks in order to plan a defensible course of action.
Based on the inspection results, BBWC would then determine if it was necessary to design a new pipeline or opt for continuous rehabilitation. The other option, if feasible, would be to repair any defects in a timely manner to ensure the proper operation and safety of the pipeline, all the while making informed capital decisions.
A lot was at stake, which was why the inspection was so critical to BBWC.
Tethered Sahara technology accurately locates leaks with sub-meter accuracy.
To ascertain the condition of the line, BBWC selected the Sahara leak detection platform for the inspection, conducted over three days with seven insertion points along the affected pipeline. Sahara is an inline tethered tool that can assess pipelines 152mm and larger, without any disruption to service.
Propelled by a small parachute inflated by the product flow, the tool requires a flow velocity as little as 0.3 m per second to progress through a water main. From a single insertion, the tool can travel more than one kilometer if flow, pressure and pipeline layout allow it.
Because the sensor tool is tethered, an operator can stop and reverse the tool to investigate acoustic events such as leaks, gas pockets and visual anomalies. At the same time, an above-ground operator locates the sensor above ground.
Pipeline commissioned exclusively for inspection.
The mothballed Venta-Alta-Ollargan-Etxebarri pipeline was commissioned exclusively for the inspection, which took 3-4 hours to fill and bring up to pressurize again. BBWC initiated a flow rate of 650 l/s and 700 l/s in order to obtain a flow velocity of approximately 0.6 m/s. enough to propel the Sahara sensor. Pressure varied between 1.2 and 2 bars.
As mentioned, owing to the early completion of the Venta-Alta-Ollargan-Etxebarri inspection, crews then mobilized to perform two additional surveys, one day at the Venta Alta treatment plant and the following day on the reinforced concrete pipeline than runs under the Bilbao River.
During the entire five-day survey, the Sahara mobilization crews kept in constant contact with BBWC, accurately communicating the inspection time, depending on the length of each of the pipe sections, number of fittings, access difficulty, etc. in order to the limit the supply and avoid the unnecessary waste of water.
While the crews faced some challenges, overall all three inspections were successful, and went off without a major hitch.
Inspection results prove that for most pipelines, age does not matter.
Analysis of the acoustic data identified no new leaks along the 2800 meters of inspected Venta-Alta-Ollargan-Etxebarri pipeline. For a pipeline decommissioned for over 40 years, the line is in surprisingly remarkable condition.
Three leaks were identified on the reinforced concrete pipeline, all located under the river. Knowing the current state of the pipelines, Bilbao Bizkaia Water Consortium can now make informed capital decisions on whether to repair or rehabilitate the lines. Knowledge is power.