Rail welding technologies are essential for high speed tracks and heavy haul tracks, to achieve safety of their transportation service, and highly reliable rail welds are required for the safety of railways. In this report, we give an outline of the four welding methods used for rails presently in the world, thermite welding. Further, we described a few quality issues seen in rail welds in overseas heavy-haul freight railways. In the last chapter, we introduced our new flash-butt welder, which we recently installed, in order to discuss the issues