The purpose of this study is to investigate and to further learn the advantage and disadvantage of progressive pipe diameter sizing in comparison with singe size pipe diameter sizing for steam transportation line. The fluid in subject of the study is dry saturated steam. The investigation is focused on the pressure drops along the pipeline, heat losses, steam velocity and the effect of erosion for each pipe size. The correlation that is used to determine the pressure drops are simple friction losses for straight horizontal pipes without any mechanical losses but thermal losses, Lockhart-Martinelli for 2 phase fluid flow, Harrison-Freeston for single phase fluid flow. The result of the investigation is expected to give us more insight view of the advantage and disadvantage of using progressive pipe diameter sizing in comparison of single pipe diameter for transporting steam throughout some distance by means of pipeline system.