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Introduction

Pipeline – this is defined as a “special form of transport used to transport liquids (i.e. liquids and gases), or liquid mixtures with solid particles”. The issue of thermographic pipeline inspection applies to long-distance piping systems supplying variable media with a temperature different from the temperature of the surrounding atmosphere. By using thermographic systems, it is possible to determine and localize defects to pipeline insulation and leaks of the transferred media. In some cases, leaks can even be determined and localized in underground pipelines.

The reliability of the piping can suffer through poor design, improperly selected material or a defective construction of the whole transport system or from unexpected conditions when in the operation. This text deals with external piping systems that are permanently affected by atmospheric influences and are threatened by unpermitted interventions (mechanical damage due to lack of knowledge, accidents or intentional actions). The damage can be reflected as weakening of the cladding on the external insulation and leaks of heating energy, as well as breaks in the piping and the loss of the transported medium. At the same time, there is the risk of the wear on the thickness of the piping through internal corrosion (during the transport of aggressive liquids) or mechanical stressing (in the case of the transport of non-homogeneous materials with solid particles).

Aviation inspection of pipelines

To resolve the problem of inspecting long-distance pipelines, an elegant and simple solution is available at first sight. Application of UAV with a camera that can fly above the whole length of the pipeline while recording and displaying the monitored scene in real time.

The operator controlling the drone from a safe place has an immediate overview of the condition of the pipeline and if identifying a defect, can focus in detail and personally check the area. However, a traditional camera for the visible spectrum discovers only a fraction of the defects, or records only areas with visible damage or leaks.

A traditional camera does not detect defects to internal heat insulation and the escapes of media below the surface of ground. With the timely discovery of areas where the insulation is thinner or where the cladding on the tube is damaged, major accidents can be prevented that would result in economic losses and a threat to the health and lives of the public. A thermal camera can detect such defects and record the thermal radiation of objects. On the basis of the difference to the surface of the pipeline and the experience of the operator, hidden defects can be found.

The company Workswell developed the Workswell AIRvision system, which combines two camera systems - a visible spectrum camera (for inspection of visible defects found by thermal camera) and a thermal camera for detecting the problems mentioned above. The servicing software enables to remotely switch camera regimes, to record radiometric videos or to make static images in both the visible and infra-red spectrum. The operator sees the objects under the drone in real time or can analyse records and identify damaged areas.

Moreover, Workswell AIRvision, unlike similar systems, enables to manually set the range of temperatures, e.g. in the interval of 15 °C to 25 °C. Even this range of temperatures can be changed during the flight. Without the need to land, the system actual situation can be set for the system and to easily achieve the required thermal sensitivity setting, which is required for the localization of minor moisture defects or the most precise localization of large defects. Traditional photo documentation is required to localise a defect, therefore, the Workswell AIRvision video camera is of sufficient quality to produce a traditional photo. Moreover, the system can be fitted with a GPS sensor for storing information about the position of the drone when creating a record.

The system can measure temperature at the central point, as well as in the local minimum and maximum. Minimum and maximum are localized using a blue (minimum) and red (maximum) cross. This function can also be used to navigate drones because the system automatically shows where the largest potential problem is located.

Produced records are fully radiometric, including videos. After termination of the flight, the records can be evaluated using the Workswell CorePlayer software to produce a measurement report on measurement with the exact localization of the problems. For this reason, a photo is available of all produced thermal images (thermogram).

Individual photos from the radiometric video can be taken and used as separate thermal images (thermograms) to analyse a problem.

More informations about drone thermal imaging system Workswell AIRvision including datasheet and drawings.