Solid particles can be transported as a mobile granular bed, known as bed-load, by pressure-driven flows. A common case in industry is the presence of bed-load in stratified gas-liquid flows in horizontal ducts. In this case, an initially flat granular bed may be unstable, generating ripples and dunes. This three-phase flow, although complex, can be modeled under some simplifying assumptions. This paper presents a model for the estimation of some bed-load characteristics. Based on parameters easily measurable in industry, the model can predict the local bed-load flow rates and the celerity and the wavelength of instabilities appearing on the granular bed. (C) 2012 Elsevier Inc. All rights reserved.37856275636Petrobras S.A. [0050.0045763.08.4]FAEPEX/UNICAMP [1435/12]Petrobras S.A. [0050.0045763.08.4]FAEPEX/UNICAMP [1435/12]