What is the appropriate tool to use for removing burrs from inside a pipe?

The appropriate tool for removing burrs from inside a pipe is a reamer. A reamer is specifically designed to smooth and enlarge the internal diameters of holes, which allows it to effectively remove any burrs or sharp edges that may have been left behind after cutting or drilling. This is crucial in plumbing and sewage treatment, as burrs can create turbulence in fluid flow and lead to damage or blockage in the piping system.

While files are useful for smoothing surfaces or removing small amounts of material from external surfaces, they are not typically designed for use inside pipes. Hacksaws are more suited for cutting through materials rather than finishing or cleaning internal surfaces. Pipe cutters are designed to cut pipes cleanly but would not be effective in addressing internal burrs. Therefore, the reamer is the correct and most effective tool for this specific task.