Experiments were conducted to investigate hydrate/ice plugging and deposition mechanisms from water dissolved in a liquid condensate system, using a single-pass flow loop. Two different hydrate/ice plugging mechanisms were observed. Hydrate/ice deposition from a dissolved-water phase resulted in a lengthwise uniform/dispersed deposit and a gradual pressure drop increase. The dispersed deposit acted as insulation at the flow loop wall, and the deposit began to propagate downstream. However, cooling below the liquid-water saturation curve resulted in free water coalescence, and a localized hydrate/ice restriction in the flow loop. This localized restriction resulted in a rapid pressure drop increase. (C) 2009 American Institute of Chemical Engineers AIChE J, 55:1882-1988, 2009