We sometimes utilize tools in our mechanical piping trade, knowing its application but maybe not knowing the tool’s history. Such it may be with the familiar pipe wrench.
The “pipe wrench” is in the family of adjustable wrenches but is unique in that the design only accommodates circular objects, such as pipe, bar or tube. The wrench is comprised of a metallic handle which has a toothed lower jaw and an upper toothed jaw (“hook jaw”) that is moveable by the use of a circular nut. The upper jaw rocks a bit in the frame of the wrench and when you apply forward pressure on the handle, the upper and lower jaws come together.
Today, the pipe wrench is 150 years old, having been crafted by Daniel C. Stillson, a mechanic at the Walworth Company in Cambridge, Massachusetts. On October 12th, 1869, Stillson received U.S. patent #95,774. Over the past 150 years, the pipe wrench has changed but the design has virtually remained the same for the past 100 years.
Proper positioning of the wrench on the material is a very important part of the wrench adjustment. The correct fit will center the pipe between the fixed and moveable jaws but leaving a very important ½” gap between the shank of the hook jaw and the pipe. This gap allows the hardened jaws to pivot and increase their grip on the pipe as additional force is applied to the handle. Allowing the back of the hook jaw to come in contact with the pipe reduces the gripping act of the wrench and will cause the wrench to slip.
In the early years of the 20th century, gas, steam and water distribution lines were made from iron pipes … some still in use today. The pipe was threaded on each end and screwed into connections and other items with internal threads. Each joint had to be leak proof, requiring considerable torque for turning the pipe and connections. The Stillson wrench, with its natural “wedging action”, was perfect for the application, having enough torque to make certain the connection was leak proof.
Today, there are six major categories of pipe wrenches; manufactured in various materials including iron, aluminum and stainless with sizes ranging anywhere from 6″ to 60″. (Pipe wrenches are classified by the length of the handle.) The categories are:
- End Pipe Wrench
- Offset Pipe Wrench
- Compound Leverage Wrench
- Strap Wrench
- Straight Pipe Wrench
- Chain Pipe Wrench
Prior to the Stillson wrench, early pipe wrenches were one of two types: screw wrenches and tongs. The screw wrench was fastened to a pipe by turning a screw and tongs required the use of two hands to pull the handles towards each other. Upon mass production in the early 1920’s, the pipe wrench came to replace the different wrenches a worker had been forced to carry in his toolbox.
When you’re looking for that one tool in your box to take care of all your pipe fabrication needs … carbon, stainless, nickel alloy and chrome moly … call Dixie Mechanical. We are your one stop solution.
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