The use of compact, inline separator has gain interest in the effort of reducing the size of topside facilities to reduce the capital cost associated with natural gas exploration. This paper discusses the effect of superficial gas velocity on the separation performance of an inline horizontal swirl tube separator. In this study, the superficial velocity is varied from a minimum of 5 m/s up to a maximum velocity of 12 m/s at different operating pressure. The pressure is varied from 40, 50 and 60 bars, corresponding to different centrifugal force on the incoming gas stream. Results shows that the best separation performance is achieve at higher operating pressure, in this case at 60 bar, regardless of the incoming fluid velocity and liquid load (of up to 30 by mass). © 2014 Trans Tech Publications, Switzerland.