Dynamic forces on a single horizontal tube have been investigated in a two-dimensional fluidized bed, and key mechanisms relating to buffeting forces on tubes have been identified. The net force acting on the tube, as well as pressure profiles around it, have been measured simultaneously by strain gauges and pressure transducers. Pressure forces resulting from the gas pressure distribution have been calculated and compared with the actual forces measured by strain gauges. The experimental results have been matched with visual observations, and the characteristic transient force profiles are distinguished. In general, the net force experienced by the tube due to a single bubble passage correlates well with that calculated from the pressure distribution, predicted using the simple Davidson model, except for the period corresponding to particle wake impact. The force due to wake impact is considerably larger than that due to the dynamic pressure distribution, but is significantly reduced when a bubble splits due to the presence of the tube.