What is the proper name of the tool used to cut the threads of a steel pipe?

The correct answer, “DIE,” refers to a tool specifically designed for cutting external threads on a cylindrical workpiece, which is typically a steel pipe in this context. The die shapes the pipe's outer surface to form precise threads that allow it to be connected to fittings or other pieces of piping securely. When tightening connections in plumbing or gas systems, these threaded ends enable a tight seal to prevent leaks.

In contrast, a pipe cutter is primarily used for cutting the pipe itself to the desired length rather than threading. A tap, on the other hand, is used for cutting internal threads within a hole, allowing for the threading of screws or bolts into materials. Lastly, a reamer is utilized to smoothen or enlarge existing holes rather than cutting threads. Each tool serves a distinct purpose in pipework and plumbing tasks, emphasizing the importance of using the right tool for thread cutting, which the die provides effectively.