%K Drilling platforms; Flow separation; Intersections; Liquids, Diameter ratio; Downstream equipment; Experimental investigations; Gas-liquid separation; Liquid carryovers; Off shore platforms; Slug flow; T junctions, Phase separation, diameter; experimental study; gas flow; multiphase flow; pipeline; separation; slug flow; two phase flow %L scholars9827 %O cited By 21 %X T-junctions are often used in offshore platforms to partially separate gas from produced fluids. Poorly designed T-junctions frequently produce very high liquid (oil and/or water) carryovers, causing major issues to the downstream equipment train which is not designed to handle excessive liquid. This paper reports the liquid carryover experiments in T-junctions using five different side to main arm diameter ratios under slug flow regime. The obtained phase separation curves can be divided into two component variables; liquid-carryover threshold and peak liquid carryover. The experiments demonstrate that with a decrease in diameter ratio both of these variables decrease. Yet, for superior multiphase flow separation, a high liquid carryover threshold and a low peak liquid carryover are required. Hence, the generally accepted rule that a reduction in diameter ratio improves the phase separation is revealed to be an over-extrapolated statement. The novel findings of this work are: 1) for optimum flow splitting under slug flow conditions, the diameter ratio should be kept between 1 and 0.67, while the diameter ratio 0.67 was found to be most suitable; 2) two correlations were developed for predicting two-phase slug flow separation in different diameter ratio T-junctions. These correlations offer beneficial guidance and clarifications for a number of oil and gas flowline and pipeline applications. © 2018 Elsevier B.V. %A A. Saieed %A W. Pao %A B. Hewakandamby %A B.J. Azzopardi %A D.A. Wood %A H.M. Ali %D 2018 %I Elsevier B.V. %P 139-150 %T Experimental investigation on the effect of diameter ratio on two-phase slug flow separation in a T-Junction %J Journal of Petroleum Science and Engineering %R 10.1016/j.petrol.2018.06.033 %V 170