Experiments have been conducted using 1.7 mm and 4 mm particles transported in a pipe 52 mm in diameter. The carrier fluids were water and clay slurries with yield stresses. In several experiments the yield stresses were high enough to support the particles in non-now situations. A two layer model was found to be appropriate for interpreting the pressure gradients, with both Coulombic and kinematic friction playing important roles. Kinematic friction appeared to confirm recent experimental results obtained with relatively coarse particles in vertical flows.