PSI - Issue 13

M. Amara et al. / Procedia Structural Integrity 13 (2018) 2137–2142 Author name / Structural Integrity Procedia 00 (2018) 000–000

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a)

b) Fig.4. The parts of pipe (a) and the particle trajectory simulation (b).

3.1. Effect of the opening angle of the valve on the erosion rate The evolution of erosion rate distribution along the pipe elbow is shown in Fig. 5. The variation is determined by the influence of the opening angle of the valve (α) taken for 15°, 30°, 45° and 90°; with different sand particle diameters of 2 mm, 0.4 mm and 0.001mm. The erosion rate for the valve opening angle of 15° is greater by 8 times to the other opening angles of 30°, 45° and 90° while it is minimal for the angle of 45°, Fig.5.a. The affected zone is localized on the part 3 of the elbow. The presence of peaks informs us that the significant of erosion rates in which subsequently tend to decrease. Reducing on the particle size, the erosion phenomenon behavior manifests in the same way for the small opening angles as for the narrow opening as shown in Fig. 5. b. The erosion rate for 90° is more noteworthy than 45°, 30° and 15° which are negligible, this occurs when micron diameter fine particles are present as shown in Fig.5.c. The part 3, which shows the part of the elbow which, has a significant erosion rate.

Fig. 5. Erosion rate along the pipe with particles diameters of 2mm(a), (b) 0.4mm and (c) 4µm

3.2. Effec t of sand diameter (particles) on erosion rate The most dominant particle size on erosion rate elevation with the opening angle of the valve is the particle of type A (large particles), except for the angle of 90°, as showed in the Fig.5. For this completely opening of the valve, the smaller particles counterbalanced the increase of the rate of erosion as shown in Fig. 5.d. Part 3, which represents the elbow, has the maximum of erosion rate which is presented either by peaks or zones a, b. Along the pipe, the most damaged area is represented in the range of zone "A". The size of the particles has an important influence on the establishment of the pipe deterioration caused the larger particle size, the more affected area will be located on the neighborhood on the part 4 away from the valve opening and if the size tends to decrease, erosion is close to the inlet of the pipe and elbow which shown in Fig. 5. 3.3. Degradation and reduction on the thickness tube The difference between the measured average wall thickness value and the nominal wall thickness determines the rate of thinning. The minimum thickness, obtained by the numerical simulations, confirmed that an exponential form which can be written as the following equation � � � � � ��⁄� � � , Fig.6.a. It notes that the reduction in the thickness of the pipe is influenced by the valve opening where it has a maximum reduction of thickness of 17% for the opening of 45°. For 30° there is a 12% for thickness reduction. About 15° and 90°, they have the same reduction of thickness of 10% . This reduction in thickness is an important at the beginning part of the pipe and decreases until it is stable Fig. 6.b. It deduced that the pipe subjected to the erosion-corrosion phenomena as noted by [12]. Table 2 recapitulate the different parameters of the reduction equation of the thickness tube.