Detection of the thickness of scale on the inner surface of water pipes by infrared thermography
The infrared thermography technique developed in the present study was successfully applied to determine the scale thicknesses of the steel pipe. We aim to estimate the thickness of the scale on the inner surfaces by calculation of the maximum temperature of the infected pipe heated surface. Dimensions of the pipe and those of the layer of scale are taken as geometrical parameter. We have studied the effect of each one on the thermal response of the considered structure. These information are important for determining dangerous state of water distribution network.
The numerical modeling and the infrared thermography principle applied to the analysis of corrosion defects in oil Conduits
Currently the corrosion phenomenon becames a serious concern to several industries of metals and particularly of steel like nuclear, chemical and petrol industries. Such defects can occur severe economic and social damage, that’s why it’s so important to detect them as soon as possible to avoid those lost. The purpose of the study is to show by calculating of surface temperature the effect of corrosion defect which can exist in these conduits. To undertake the study we modelled conduit (tube) by a steel cylinder and the defect by a circular layer of rust. Dimensions of the cylinder and those of the layer of rust are taken as parameters. To see the effect of each geometrical parameter on the thermal state of the considered structure we studied the thermal state of the structure by taking this parameter like variable and all the others as constant. In fact, when a material is thermically requested (artificial excitation in the case of Laboratory measurements or natural excitation in the case of in-situ measurements), the heat diffuse in uniform way in material. The presence of a defect within the material (e.g. a crack or a rusted layer) acts like a heat insulator and idle this diffusion. It follows from there the appearance of a hotter region on the surface compared to the close one without anomaly. The study is undertaken on a cylindrical structure, as on the figure below, of geometrical parameters: external diameter d=254mm. The cylinder thickness ep =19mm, the length of tube l =1m. In order to detect the rust thermal effect on the thermal state of the steel pipe, many situations are considered. The study concerns the effect of rust thickness, rust depth and finally the number of rust layers in pipe on the surface temperature at the structure.
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