Solid Deposit Effects on the Pressure in Closed Pipes

Pressure surges seen as wastewater reflux and geyser, overflowing and pipes burst are likely to be related to the solid deposit layer development in closed collectors. However, this danger still needs to be not fully understood. In this work, we evaluated the effect of pipes bottom modification due to the solid deposit on the pressure changes. Exner Saint Venant equations under the hypothesis of uniform and stationary flow were used for the solid deposit layer development effect on pressure changes modeling. Both analytical and numerical solutions in gravity as well as in a pressurized pipe were calculated. Since the solid flow is an important parameter in this calculus, we used the Wang and the Graf formulas as well as several different others proposed in the literature to ensure its estimation. Then, we compared the obtained results in order to select the suitable one that neither underestimates nor overestimates the pressure change. The results showed that the pressurizing of free surface flow pipes are significantly affected and that pressurized conduits are more exposed to this danger due to the solid deposit layer. Thus, to avoid this phenomenon, the pipes bottom and the pressure modification have to be evaluated using the most appropriate solid flow formula.