In this paper, Hougaard process stochastic degradation model has been used for the prediction of wall thickness reduction in pipes between two consecutive in-service inspections. Experimental data on FAC in gypsum orifice, from the literature, were used. There were nine locations downstream of the orifice where the wear of wall was measured at 1 h, 2 h, 3.5 h, 4.5 h, 6.5 h, 9.6 and 13 h into the experiment. The predicted wall thickness reduction compared well with the experimental wall thickness reduction from 9.6 h to 13 h.