IR thermography is applied to detect hidden corrosion on carbon steel pipelines for oil transportation. The research is oriented to set up a robust technique to carry out in situ the early detection of corroded zones that may evolve either towards leakage or failure. The use of thermography associated with a transient thermal technique is investigated on 12.2 mm thick samples, machined to artificially create a reduction of wall thickness that simulates the effect of real corrosion in pipes. The extension and depth of the artificial defects is controlled by ultrasounds which represents the reference for the results obtained by thermography. Two approaches are proposed: the first is based on the processing of a single thermogram taken at the optimum time after a finite pulse heating of a large area of the external surface; the second technique is carried out by scanning the pipeline by means of a device composed of a linear lamp and a thermographic camera which move jointly over the surface to test. A suitable reconstruction provides a map of the tested surface with possible hot spots in correspondence with the corroded areas. The analysis of the thermal problem by Finite Element Method is used to optimize the experimental parameters. The experimental results demonstrate a detection capability starting from 15 % of wall thickness reduction.
IR thermography is joined to a simplified thermal model for evaluating thermal performance of insulated containers. The method is illustrated with experimental results obtained into a test tunnel working under controlled environmental conditions. Insulated vehicles are tested in parallel according to the accepted standard "Agreement on the international carriage of perishable foodstuff" (ATP) and the thermographic method. A thermographic apparatus is used to map the temperature of the external walls of the insulated box. Defective zones are identified and the local heat flux mapped basing on a heat flux meter measurement in a reference point and on the thermographic temperature maps. The proposed thermographic method allows also determining thermal bridges magnitude and air leakages location. These results are important in order to enhance manufacture. Some experimental data are presented in order to compare K-values measured along ATP rules and calculated by the thermographic inspection. The comparison allows verifying the accuracy. Such a quality test is particularly useful for periodic control of insulation ageing.
