The detailed Bow structure and characteristics of moving bed flow in pipes in the presence of an either co- or counter-currently flowing interstitial gas are studied both experimentally and theoretically. Experiments are performed with 0.2 mm diameter sand particles in an L-valve installation operated in the moving bed flow regime both in the vertical and horizontal pipe. Accurately characterized bed porosity and specific area variations revealed behaviour different from that suggested in the Kojabashian classification. A simple design and prediction method is presented and tested for the calculation of moving bed lines.