The carbon steel pipelines used for transporting oils generally have water flowing concurrently with the oil phase. The presence of water can lead to internal corrosion problems such as when free water contacts the wall surface; namely the steel corrodes when water wets the surface. Therefore it is pertinent to study how the distribution of water under different oil-water flow conditions can affect the surface wetting whether the wall surface is wetted by water or oil phase.In this experimental work a large scale 0.1m ID inclinable flow loop was used to study the two phase oil-water flow in horizontal and vertical positions. Paraffinic model oil and 1wt% NaCl in deionized water were utilized as the test fluids. Two measurement techniques: flush mounted conductivity pins and high speed camera were employed for surface wetting determination and flow patterns visualization respectively. The wetting data were analyzed based on four types of wetting behaviors: stable water wet unstable water wet unstable oil wet and stable oil wet. The wetting results from the conductivity pins were found to match with the visualization results from the high speed camera. The horizontal flow results showed that water flows separately and wets the pipe bottom at low velocity but not all of the water is fully dispersed at higher oil velocity as traces of water can still be found to wet the surface intermittently.Keywords: water wetting oil-water flow flow pattern conductivity pin wettability corrosion high-speed camera