Joint paths are induced mathematically for many kinds of joint pattern between master-and subpipes. By compensating them with root gap of welds and kerf width, real cutting paths are determined. Their NC codes are generated, and the paths generated by NC code are verified by a ghost function. A beveling is implemented through tilting a torch in the A-and B-axis direction for 8 sections in the chuck rotation of C-axis. The effective CAM program was developed specially for 6-axis CNC pipe coasters which cut a master or sub-pipe along the cutting path and simultaneously fulfill a beveling process.