In Sweden, consulting engineers Arne Jensen AB use a ThermaCAM™ PM 695 from FLIR Systems to detect leaks in the underground pipes. “Thermography is an excellent way of rapidly obtaining a clear overall picture of the status of the entire network”, says Arne Schleimann-Jensen, founder of Arne Jensen AB and chairman of the company.
Locating underground leaks
Using thermography on a district-heating network
involves scanning the network from the ground with a thermal camera. The
inspections can be carried out at night when there is less traffic.
Additionally, temperature differences are even more visible at night
because it is generally cooler. The thermal images produced by the
camera clearly show the location of temperature rises, which may
indicate that heated water has spread into the insulation, or into the
ground. Since the thermal images locate leaks extremely accurately, they
are an invaluable resource when the time comes to dig and repair.
The thermal images can be used not only for fault location but also to classify and prioritize faults. The thermal camera allows even minor problems to be followed up and repair work to be scheduled as necessary.
Saves money and increases safety
Checking the status of a district heating network with infrared thermography is a quick and cost-effective way to reduce maintenance costs and improve safety.
Reports produced with FLIR Systems ThermaCAM™ Reporter™ software give a clear and easy-to-interpret picture of any leaks so that you can avoid digging in the wrong place. This can save a lot of time and money!
Continuous use of thermography on the district-heating network can also increase the life of the entire network. Because the thermal camera can highlight the critical points, you avoid unnecessarily replacing the entire network and can concentrate instead on repairing the detected faults.
Repair costs can also be reduced since faults are found at an earlier stage, before the pipe insulation is seriously damaged.
Rapid location of leaks means that district heating plants save a great deal of money because of the reduction in losses of heated and treated water.
Safety risks are also minimized, especially in winter. In Sweden the pressure in the pipes can reach 16 bar, and the temperature of the water reaches 120°C, so above-ground leaks can have serious safety consequences.
In Sweden, many operators of district heating networks routinely use thermography as part of their preventive maintenance programs. “Many plants carry out a check in the spring in order to find out what happened during the winter when the load was high”, Arne Schleimann-Jensen explains. “This makes it easy for them to schedule any necessary repairs during the summer.” Other operators prefer to carry out a condition check in autumn to reduce the risk of acute leaks arising in the middle of winter. This is the time when output is high and the demand for heat is at its greatest, and therefore when repairs would cause most disturbance.
One thing is clear: more and more district heating operators are discovering the benefits of using thermography on their networks. Whether you do the work yourself or engage an outside firm, there are big benefits to be gained through early detection of problems leading to reduced maintenance costs and disturbances, lower energy and water wastage, and minimized safety risks.