A series of physical models consisting of three different diameter pipes at the same 4% slope were studied at the Utah Water Research Laboratory (UWRL). Various combinations of air flow and head on the pipe were used to determine the effect of pipe diameter, head, and air flow on the behavior of air bubbles introduced into the pipes and to determine the venting capacity of the pipes. It was determined that neither bubble velocity nor bubble length changes with pipe diameter or head changes within the range tested. It was also determined that bubble velocity and length will increase with increased air flow. Bubble velocity also increased with increasing bubble length consistent with prior research. Overall the venting capacity of a pipe is dependent upon having a large enough pipe to prevent slug flow. A procedure was developed to aid in the sizing of submerged vent piping during the design of pipelines based on the data collected during this study and utilizing prior research.