Erosion-Corrosion of AISI 302 Stainless Steel Sudden Expansion Pipes in High Salt Wastewater: Effect of Fluid Flow on Different Positions of a Sudden Expansion Pipe

Erosion-corrosion (E-C) is common in chemical industries. Sudden expansion pipes (SEP) are one of the flow components which may experience severe erosion rates. Computational fluid dynamic modeling (CFD) and flow-through experiments were used to study E-C for a SEP of AISI 302 stainless steel. A typical geometry for SEP was investigated: 20 mm diameter inlet pipe, 40 mm diameter outlet pipe, with an inlet flow rate of 0.1 m/s, and 10 wt% concentration of SiO₂. CFD simulation results showed that turbulence energy and wall shear were highest at 5 mm and fluid axial velocity was lowest at 5 mm from the inlet/outlet SEP connection point. E-C test results showed that the most severe E-C occurred between 5 mm and 7 mm downstream of the SEP. At deeper lengths into SEP, the corrosion rate decreased and remained constant. The results indicated that increasing wall shear and turbulence energy increased the mechanical effects of particles on SEP and hence increased the E-C rates of the reattachment point. This work provides a means of understanding E-C behavior and predicting erosion damage of SEP.