Abstract

DARWEESH, Moustafa S. Predicting the head leakage behaviour of cracks in pipe elbows. Water SA [online]. 2022, vol.48, n.1, pp.56-61. ISSN 1816-7950.  http://dx.doi.org/10.17159/wsa/2022.v48.i1.3910.

In this study, finite element analysis (SAP2000 program) was used to investigate the relationship between the pressure and leakage area in 90° pipe elbows with longitudinal, spiral, and circumferential cracks. The results show that leakage areas expand linearly as the internal pressure increases and its inclination is called the pressure-area slope (m). A sensitivity study was conducted to recognize the influence of different parameters (inside diameter, wall thickness, modulus of elasticity, longitudinal stress, Poisson's ratio, and finally crack orientation) on both m and leakage exponent (N). The results reveal that the elasticity modulus has the dominant impact on m, followed by elbow wall thickness, and then elbow inside-diameter. The Poisson's ratio and the longitudinal stress have an insignificant influence on m. Moreover, the slope m varies more in the longitudinal and spiral cracks than the circumferential cracks. The amount of leakage through the different cracks is a function of the internal pressure raised to an exponent ranging from 0.5 to 1.01. An attempt was made to find empirical equations to express the pressure-area slope as a function of elbow properties and crack orientation. The study's findings were checked against numerical and experimental results and good correlations were obtained.

Keywords : cracks; finite element model; leakage; pipe elbows; pressure.

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