PSI - Issue 5

S. Sahnoun et al. / Procedia Structural Integrity 5 (2017) 1267–1274 A.Saifi et al/ StructuralIntegrity Procedia 00 (2017) 000 – 000

1270

4

tube with a thickness e p = 2 cm and a diameter d = 12cm. We have shown in figure. 3 the evolution of the absolute thermal contrast along the axis AB of the pipe for the cases considered.

Fig. 3. : The temperature variation along the AB axis for the three cases considered. The curves of the absolute contrast variation obtained show that the more the scale layer thickness increases the surface temperature of the controlled pipe is important. This result can be explained by the low thermal effusivity of the scale, which slows down the diffusion of the heat towards the inside of pipe. This facilitates the control of the conduits by infrared thermography. 2.3. . Effect of pipe thickness on absolute thermal contrast In the industry there are the deposits of scale on pipes of different sizes. To study the pipe thickness effect, we have fixed the scale layer thickness, and we considered three pipe with thickness different e p = 10 mm, e p = 20mm and e p = 30mm. The figure below shows the evolution of the absolute contrast along the axis AB of the pipe for the three cases.

Fig.4 : The temperature variation along the AB axis for three pipes which have different thicknesses. According to the above figure the curves obtained are confounded. Indeed, we can note that the absolute contrast is not sensitive to the thickness of the pipe. This is due to the high thermal effusivity of the steel. 2.4. . Effect of pipe diameter on the absolute thermal contrast In the latter case, we have considered a pipe which has a fixed thickness e p =2cm whose we have varied the diameter of d=240 mm, d=140 mm and d=80 mm. The layer of scale is taken equal to y = 3cm. The figure shows the evolution of the absolute contrast along the AB axis of the pipe studied for the three cases considered.