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Call for innovative solutions for leak detection in heating networks

By ENGIE Réseaux


  • idatase GmbH

Call for project closed the 20|12|18

ENGIE Réseaux is looking for innovative solutions for locating water leaks more accurately within functioning heat networks and for better evaluating leakage flow.


  • Districlima

Object of the call for project

ENGIE Réseaux in the Bourgogne Franche Comté Region wants to find out about innovative solutions for improving the performance of its currently-operating urban heat networks. The aim is to more accurately locate water leaks in functioning heat networks and to better evaluate leakage rates.

The purpose of this call for projects is to find a technology that will allow us to provide a system that complements the solutions that are currently being used (see annex for details of the solutions being used) to locate leaks in hot and overheated water networks:

  • Quantity of reserve water
  • Testing pressure drops between sections
  • Injection of tracer gas
  • Monitoring leaks using electrical resistance
  • Listening via the floor.
  • Acoustic leak correlator
  • Infrared Thermography.

These techniques are not are not always sufficient for detecting leaks with enough accuracy, which can require road work to be done, sometime with significant disruption of city traffic and high costs. The nuisance and costs incurred could be reduced by more accurately locating leaks. Similarly, being able to estimate leak rates would make it possible to assess how critical they are and categorize how urgently works have to be done.

The innovative solution you are submitting should be able to:

  • locate a leak to within 50 cm
  • evaluate leakage flow without causing cuts in the heat supply
  • reduce implementation costs.
  • The system must be easy to use and robust.

Gain and benefits

Rewards and benefits for the winners of the call for projects

  • ENGIE Réseaux Bourgogne Franche Comté will give the winner 9 months to set up a pilot.
  • The winner will be allowed to organize a series of tests for leaks on the Chalon-sur-Saône heating network at the initiative of and in collaboration with ENGIE Réseaux Bourgogne Franche Comté. Other tests may be held for other ENGIE heat networks.
  • Depending on the outcome of these tests, a commercial partnership may become possible and potentially extended to the entire scope of ENGIE Réseaux’s businesses.
  • The winner(s) and ENGIE Réseaux will also develop a communications campaign together (announcement of the winner, communication about the project implementation).
  • The winning project will also get support from Nicéphore Cité, a partner in the call for projects.

Deadline for submitting applications: December 20th, 2018.

Description of the call for projects

Selection criteria

  • Suitability with the subject,
  • Accuracy with which leaks are located,
  • Estimation of leakage rates,
  • Innovative nature,
  • Ease of implementation,
  • Quality/price ratio.
  • Speed of implementation.

Who is this call for projects for?

Startups and innovative companies

Provisional timetable

  • Project Launch: October 1st, 2018.
  • Deadline for submitting applications: December 20th, 2018.
  • Selection committee meeting dates: beginning of February 2019.
  • Presentation of shortlisted projects for the selection committee/pitch at Nicéphore Cité in Chalon: end of February 2019, followed by the announcement of the winners.


Partners in the call for projects

Nicephore Cité, accelerating innovative projects

Making companies more attuned to the challenges of digital technology; giving them the right tools and supporting them through their digital transformation and the implementation of new uses, processes and services; helping innovative project leaders: these are the current missions of the Digital Engineering Centre, which is operated by Nicéphore Cité in partnership with the Image Institute and other stakeholders in the innovation network.

This support is offered through a special service offering including a high value-added services incubator, tailor-made training, a FabLab for prototyping and small runs, and virtual and augmented reality solutions.

In addition, a program of events on innovation and entrepreneurship will be made available to help companies get involved and make the digital ecosystem work for them.


Heating networks operate at variable temperatures. They are buried in the ground or in a gutter (see Appendix, §6.2 for examples) at varying depths and with variable surface typologies (pavement, sidewalk, lawns, etc.). They usually consist of two pipes, one outgoing pipe (which is hotter) and one return pipe (colder) carrying hot water, superheated water, or steam. They can have a length from several kilometers to dozens of kilometers. There are various access points (valve rooms, drain, purges, other accesses). The pipes are made of steel.

6.1 Current leak detection solutions

    6.1.1 Quantity of extra water

Leaks are usually detected by measuring the amount of extra water required by the system. This can provide a warning about the presence of one or several leaks, but does not predict its location.

For some networks in France we consider leaks to be significant if water consumption exceeds 7 m3/day, but this criterion needs to be adjusted to the specifics of different networks to account for their age and maintenance conditions.

    6.1.2 Tracer gas detection

When a tracer gas, often helium (or CO, or others), is injected into the system, the quantity injected will depend on the volume of water in it. If there is a leak, helium will be released. A robot is used to take samples every 3 m. It drills a hole and analyzes the presence of helium. The detection stage can last up to five days, because helium is retained in the soil for this period.

Success factor: 30% of leaks detected. Operators must locate the leak within 2 m in order to fix it.

Figure 1 : Robot analysing the presence of helium.

    6.1.3 Monitoring leaks using electrical resistors

Leak monitors that use electrical resistors are usually preinstalled in the pipes.

They consist of 2 electrified wires that form part of the pipe insulation. When there is a leak, the current is transmitted and an alarm is triggered.

Figure 2: pipes equipped with wiring to detect leaks.

    6.1.4 Testing pressure drop between sections

  • Isolate branches with valves
  • Check the pressure and start counting the time.
  • If there is a leak, the pressure will decrease. Note that the pressure can go down even without leqks because the valves are unlikely to be 100% watertight
  • Count to one minute and record the pressure at the end of the test.
  • This system requires having sealed valves (difficult to verify) and allows you to identify a specific sector, but not to locate leaks with precision.

    6.1.5 Listening on the ground

The operator will identify the sound or vibrations that result from water leakage from the pipes using individual (mobile) equipment.

There are several factors that affect the range of volume and frequency of the sounds produced by water leaks transmitted through the pipes to the surface of the ground.

  • Water pressure in the pipe: The volume or intensity of the leak noise is directly proportional to the pressure of the water inside the pipe.
  • Pipe material and pipe diameter: Metal pipes transmit stronger, more frequent water leak sounds than PVC or asbestos-cement pipe.
  • Soil type and compaction: Sandy soils and very loose soils, especially above freshly buried pipe, do not transmit water leak noise very well, nor do soils saturated with water such as in peat bogs and swamps. Hard and compact soil transmits the sounds of water leaks best.
  • The depth of the soil above the pipe: Soil absorbs the sounds of water leaks very quickly. Leaks in water pipes that are only 3 or 4 feet deep are much easier to hear on the surface than leaks in deeper lines. At 7 or 8 feet deep, only very large leaks with good water pressure will produce enough noise to be heard on the surface.
  • Surface cover: grass, loose earth, asphalt, concrete slab, etc. The hard surfaces of the streets and the concrete slabs resonate with the sound of the water leak, making it possible to hear the leak from 5 to 10 or additional feet on each side of the water pipe. Grass lawns and loose dirt surfaces do not provide such a resonant surface.

Figure 3: Operator conducting a ground surface noise test

    6.1.6 Acoustic leak correlator

Correlation devices locate leaks on pressurized pipes where the approximate location of the leak is unknown and the distances are relatively high.

Two (or more) sensors are placed in contact with the pipe on both sides of the suspected leak. These sensors record and transmit the sound by radio to the processing unit.

Mathematical algorithms are used to determine the exact location of certain noise profiles (such as whistles) on the pipe, correlating it with the noise that reaches both sensors and measuring the difference in displacement on the pipe.

Figure 4: schematic drawing of the correlator.

    6.1.7 Infrared Thermography.

Inspecting the network from the street level with a thermal camera with geolocation.

This kind of inspection can take place every 1 to 5 years and can cover the entire network. It can be done on foot, by car, by plane or with drone.

Due to the quantity of thermal and standard photos collected, the analysis is often done with computerized images in real time.

The analysis consists mainly of detecting hot spots, i.e. points with a difference in temperature between the street level above the network and the surrounding street that are above 10ºC (?T <10 °C).

A second level of analysis is done by comparing the hot spots with the imagery from previous years. Thermal drift (thermal drift) must be less than 3ºC (DT <3 ° C).

Figure 5: Thermographic view.

    6.1.8. Endoscopy or video inspection of pipelines.

Visualizing the condition of the insulation, the supports, the gutter and the slabs by moving a camera inside the gutter and outside the tube. The images are saved.

Real views of the condition of the network from the outside, allowing the inspector to see the level of degradation of the insulation, the state of the supports, the gutter and slabs. Reliable and convincing results when conditions are met since more than 90% of leaks come from a source outside the tube.

Only works from a network access point (valve chamber, compensator chamber, etc.) or when the network is opened for a survey. Does not allow the inspector to visualise long lengths (less than 100m, and often 10/20m). Does not allow go beyond turning points. Fragile because conducted in hot environments that can get very hot in the event of leakage. The quality of the image depends on the cleanliness of the gutter.

    6.1.9 Guided waves

Detection of variations in the of any type of steel pipe, whether operating or not. Does not directly detect leaks. Preventive use rather than active detection.

A set of transmitter-receiver sensors placed in a ring all around the tube sends guided waves of torsion to both sides of this ring. The feedback signal is then analyzed: any "offset" in the signal indicates a variation.

Figure 5: View of equipment used for guided waves

This is the only solution available to understand the piping when it enters a wall.

Highly technical material that requires experience for understanding the results. Requires substantial process to implement compared to other tools.

6.2 Main types of piping in profile.

Figure 6: profile view of a buried network.

Figure 7: profile view of a network in a gutter (with a cover in buried concrete).

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