Pipeline construction requires pipe ends be prepared for butt welding. Typically this requires dressing or cleaning up the pipe ends and ensuring they are trued-up or otherwise made parallel with to the opposing end, usually square, beveled and aligned end-to-end and welded. Often the pipe ends for one reason or another are not factory square, such as when cut in the field to fit. Such ends are often flame cut using a cutting torch and which results in a significant time to clean up the butt ends before welding together.
While grinders are used to grind off high spots, slag or other imperfections, the work is manual and can result in variable welding gaps and misalignment.