A pipe wrench consists of a heavy metal handle with a toothed lower jaw, which is attached to a toothed upper jaw with screw-like threading, allowing the width of the jaws to be adjusted with a circular nut. The upper jaw can often wiggle slightly, allowing it to more easily be positioned to grip a rounded surface. The teeth of a pipe wrench are oriented so that they will grip a rounded surface as the wrench is turned. The jaws of the wrench are also usually set at an oblique angle so that the space between the jaws gets smaller toward the back of the wrench. This allows some degree of flexibility with a given width adjustment, and also aids in allowing the wrench to properly grip a rounded object.
 

Using a Pipe Wrench

Pipe wrenches are commonly used in tasks where rounded metal objects must be gripped tightly or turned, such as plumbing. When using a pipe wrench, one will generally begin by assessing the width of the pipe which must be turned, and then adjusting the wrench so that the front side of the jaw is wider than that measurement, while the back side of the jaw is narrower. The head of the wrench is then pushed onto the pipe firmly, and then the wrench is pushed forward to make the jaws engage and grip the pipe to turn it. Putting backward pressure on the wrench will make the jaws loosen so the wrench can be removed.