Strap wrenches are particularly useful because they do not damage which type of materials?

Strap wrenches are designed with a flexible strap that wraps around the workpiece, enabling them to grip without exerting a concentrated force on a small area. This feature makes them ideal for use on polished pipe and fittings, which are often sensitive to scratching or denting. When using a conventional tool, like a traditional wrench, there's a higher risk of marring the smooth surfaces of polished materials. The strap wrench mitigates this risk as the strap’s design distributes the pressure evenly across the surface, preserving the integrity of the polished finish while providing a firm grip. This makes strap wrenches invaluable in applications where aesthetics and surface condition are critical, such as in plumbing and HVAC work.