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In this work, the pulsed thermography process applied to inspect and analyze the internal corrosion defect in a pipe. The study carried out in two stages, the first one characterizes the control of the pipe at a standstill by considering the air inside the pipe, and the second one characterizes the control during operation by introducing a turbulent flow of seawater into the simulation. For this purpose, a 3D model of a fluid pipe containing three forms of internal rust defects performed using finite element software. The influence of parameters such as the size and penetration of rust into the tube evaluated by analyzing the contrast of the corresponding thermal images and the temporal and spatial variation of the temperature. The tube thickness introduced as a parameter influencing detection.

The use of coatings is an important tool in the industry. It allows protecting against oxidation, corrosion and various types of fatigue. The coating thickness is an important characteristic that influences the quality and the performance of materials. In this paper, we develop a simple method of infrared lock-in thermography (LIT) to determine galvanizing coating thickness measurement, by using a sample multiple zinc layer with thickness ranging from 0.25[Formula: see text]mm to 1.5[Formula: see text]mm. The method has the particularity of taking a sinusoidal excitation heat flux which contributes with a heat exchange coefficient fixed at 10[Formula: see text]w/m2k and a surface emissivity of about 0.1. The finite element method (FEM) is used to model and analyze the thermal response of studied structure. The metal substrate used in this study is a structural steel, covered with six zinc layers. The finite elements analysis allows us to determine the temperature evolution at different points on the specimen. The Fourier transform method is used on the Matlab software to determine the phase angle of the data found. A correlation between the coating thickness and the equivalent phase angle is defined, and the results deduced show that the estimated values are close to the actual coating thicknesses with a precision ranging from 0.029[Formula: see text]mm to 0.011[Formula: see text]mm.