Pipe Wrench

A pipe wrench is any of several types of wrench designed to turn threaded pipe and pipe fittings, for either tightening them together or loosening them apart. The most common variant is the Stillson wrench, named for its inventor Daniel C. Stillson, a mechanic at the Walworth Company in Cambridge, Massachusetts, whose design received United States patent number 95,744 on October 12, 1869. The tool has hardened, serrated teeth that grip the softer metal of a pipe, and its jaws are deliberately loose fitting so the wrench binds onto the pipe as the handle is pushed, tightening the grip; pipe wrenches range from about six inches up to forty eight inches or larger, traditionally forged from steel, though some modern versions use an aluminum body with steel teeth and jaws. Separately, the Swedish inventor Johan Petter Johansson patented his own adjustable pipe wrench design on August 17, 1888, addressing the same practical problem of tradesmen having to carry many fixed size wrenches because pipe and nut dimensions were not standardized.