Which tool is predominantly used for tightening threaded pipe fittings?

The tool predominantly used for tightening threaded pipe fittings is the pipe wrench. This tool is specifically designed with serrated jaws that grip the rounded surface of pipes, allowing for a strong hold that is essential when applying torque to threaded fittings. The design of a pipe wrench allows it to easily adjust to various sizes of pipes while providing the necessary leverage to effectively tighten or loosen fittings without slipping.

Unlike other tools such as pliers, which may not offer a secure grip on round surfaces, or adjustable spanners, which are better suited for flat surfaces, the pipe wrench is specialized for the shape and material of pipes. It provides the strength and stability needed in plumbing and pipefitting applications, making it the preferred choice for professionals in situations involving threaded pipe fittings.