If a tube end is flared, welded, or roll beaded, the end will need to be removed prior to being pulled or knocked out. One common method for weld removal is with a grinder. While this is a fairly inexpensive method for removal, it does have a lot of challenges. The grinding process can be very time consuming and hard on operators. Additionally, if it’s not used carefully, the grinder can gouge or damage the tube sheet and tube sheet hole. If this happens, the tube sheet hole will need to be reformed or smoothed out before new tubes are installed. If damage is not repaired, it can result in a poor metal-to-metal joint.
Another method for weld removal is with an end prep tool, also known as a tube auger, boiler gun, or mill hog. This tool can be used to remove welds, flares, or beads from a tube end. End prep tools are easy to use and don’t require the same amount of precision as a grinder. The tool uses collet jaws to grip the inside of the tube while the operator turns a series of ratchets, slowly advancing a blade towards the tube sheet until the weld is fully removed.
Once the weld has been removed from the tube end, the tube removal process can begin. There are several methods that can be used to remove boiler tubes such as spear pulling, knockout tools, torching, and induction heating of the tube.