The flow pattern and power number in a vessel depend on the geometrical parameters of the impeller and the stirred vessel. This paper discusses the influence of the blade pitch angle of a six-blade Rushton disc turbine on the flow and energy dissipation in horizontal and vertical stirred vessels. Measurements for the two types of stirred vessels (diameter: 240 mm) are carried out by experiments and numerical simulations using computational fluid dynamics (CFD). The difference in the mixing characteristics and energy dissipation in the two vessels is discussed. With an increase in the pitch angle, the power number and flow pattern change gradually in the horizontal vessel and sharply in the vertical vessel. The results of the present study can be used as reference data for industrial horizontal stirred tanks.