chain pipe wrench
A chain pipe wrench is a type of adjustable pipe wrench that consists of a forged steel handle to which is attached a length of heavy sprocket chain. It is used by wrapping the chain around a length of pipe and engaging the sprockets in notches on the back of the handle. The teeth on the face of the handle bite into the pipe while the chain holds the pipe against the teeth to prevent it slipping.
A chain pipe wrench turns pipe in either direction and can be used like a ratchet wrench. The handle can be loosened, shifted, and turned again without taking the chain from around pipe. It can be used on round, square, or irregular shapes without crushing the object. Although it costs slightly more than an equivalent-sized Stillson wrench, a chain pipe wrench offers easy handling in close quarters.