 A modern pipe wrench | |
| Classification | hand tool |
|---|---|
| Related | wrench,plumber wrench,monkey wrench |
Apipe wrench is any of several types ofwrench that are designed to turnthreaded pipe andpipe fittings for assembly (tightening) or disassembly (loosening). TheStillson wrench, orStillson-pattern wrench, is the usual form of pipe wrench, especially in the US. The Stillson name is that of the original patent holder, who licensed the design to a number of manufacturers; the patent has since expired. A different type of wrench with compound leverage often used on pipes, theplumber wrench, is also called a "pipe wrench" in some places.
The Stillson wrench is anadjustable wrench (spanner) withhardened serrated teeth on its jaws. The hard teeth bite into thesofter metal of the round pipe and provide the grip needed to turn a pipe, even against fair resistance. The design of the adjustable jaw, which permits a certain amount of intentionalplay out ofsquare, allows it to bind on the pipe, with forward pressure on the handle pulling the jaws tighter. On some models, twoleaf springs, above and below the knurled adjusting knob, help unlock the jaw when pressure on the handle of the wrench is released.
Pipe wrenches are not intended for regular use onhex nuts or other fittings. However, if a hex nut becomes rounded (stripped) so that it cannot be moved by standard wrenches, a pipe wrench can be used to free the bolt or nut, because the pipe wrench is designed to bite into rounded metal surfaces.
Pipe wrenches are classified by the length of the handle. They are generally available in sizes from 6 inches (150 mm) to 48 inches (1,200 mm) or larger. They are usually made of forgedsteel. Today, aluminium might be substituted to reduce the weight of the body of the wrench, although the teeth and jaw remain steel. Teeth and jaw kits (which also contain adjustment rings and springs) can be bought to repair broken wrenches.
Daniel C. Stillson (1826–1899), a mechanic at the Walworth Company, inCambridge, Massachusetts, created the first such wrench.[1] On October 12, 1869, US patent #95,744 was issued to Stillson.[2]
On 17 August 1888, the Swedish inventorJohan Petter Johansson (1853–1943) took out his first patent on theadjustable pipe wrench.[3] The Swedish Patent Office issued the patent again in 1894.[4] The idea emerged after he established his companyEnköpings Mekaniska Verkstad. Back then, nut dimensions were poorly standardized, so each time a tradesman was out on a job, he needed a trolley to take a set of fixed pipe wrenches with him. Johansson's tool could grip nuts of different dimensions.[5]
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InSouth Africa, the terms "bobbejaan spanner" and "baboon spanner" are commonly used,[6] especially for large pipe wrenches.Bobbejaan is theAfrikaans term for ababoon.
InSpain andMorocco, they are calledgrifa.
InMexico they are known and called "stillson" without even using the wordllave ("wrench").
InTurkey they are known as "English Keys".
Daniel C. Stillson wrench.