In recent years incipient, critical, and choking cavitation levels have been introduced as design criteria for orifices and valves in pipelines. Recent studies have evaluated a fourth level, incipient cavitation damage, for orifices that is applicable to the design of sudden-enlargement energy dissipators. Design data for these four levels are included in the paper. Since cavitation in prototype structures can differ from that predicted by model studies, research has also been directed toward evaluation of scale effects. The existence of scale effects due to pressure, size, and geometry for four levels of cavitation are examined herein and methods and equations for adjusting reference test data to structures of other sizes operating under different pressure conditions are presented. The location and distribution of cavitation pitting on the pipe wall downstream from the sudden enlargement are identified. The pitting is a function of expansion ratio and cavitation intensity.