This report contains data that demonstrates the scaling of flow regime, pressure drop, and holdup multiphase flow with pipe diameter. In addition, entrance length effects, the onset of liquid entrainment, and interfacial shear modeling at high gas density were studied for purposes of validating multiphase flow design methods. Stratified, slug and annual flow regimes were observed in a 112-foot long 3.5-inch diameter test section. Air, freon, and water were used to represent pipeline fluids.