A pipe wrench , corner pipe wrench or Swedish wrench is a pair of pliers for working on pipes and the fastening elements used in pipe installation ( sleeves , union nuts, etc.). It was invented by Johan Petter Johansson in 1896 and is the classic tool for sanitary installations as well as heating and ventilation construction.
Standard pipe wrench
Pipe wrenches differ from water pump pliers in how they work. They are self-locking due to their lever mechanism. If you have roughly set the jaw width with the knurled screw of the lower lever arm, you no longer have to press the two tong arms / legs together in order to grip the workpiece firmly. To turn the workpiece, you simply press the ergonomically shaped upper tong arm. This results in an energy-saving way of working, but the pliers must be moved to turn in the other direction. The position of the gripping teeth is also only designed for working in one direction.
The distinctive gripping teeth dig into the surface of traditional steel water pipes and their connecting pieces ( fittings ). These have a sufficient wall thickness to enable powerful screwing of the threads provided with hemp or other sealants.
If the pipes are unusually tight or if the wall thickness of the pipes is too small, there is a risk that the pipe will be crushed or destroyed during the attempt to loosen it due to the self-locking effect of the pliers.
When used with hardened steel, there is a risk of blunting the sharp teeth of a pipe wrench.
Tools with smooth ( adjustable wrenches , pliers for fittings), with smooth and parallel guided ( pliers ) or with hardened jaws (screw pliers ) are more suitable for operating screws and nuts, which today are mainly made of hardened steel .
A distinction is made between pipe wrenches according to the alignment of the mouth:
- Mouth position 90 ° ("Swede")
Advantage: even when the pliers are wide open, the jaws are still exactly opposite and, if correctly adjusted, lie parallel to the edge surfaces of nuts over their entire length.
- Mouth position 45 ° ("Eckrohrzange", "Schräschwede" etc.)
Disadvantage: when the pliers are wide open, the inclined jaws are no longer facing each other, which makes it harder to grip hexagonal or octagonal screw connections.
... and according to the shape of your cheeks:
- straight (shape A, for gripping objects with parallel surfaces, such as nuts)
- one straight, one bulged (shape B, for gripping objects with parallel surfaces or round objects)
- s-shaped (shape C, for gripping round objects)
The pliers are usually available in lengths of 250–700 mm and with spans from 35 mm.
Another modification is the pipe wrench with stepless quick adjustment. Here the jaw width is not varied using the knurled screw, but by simply moving the pliers leg in the open state and by engaging it on a rack in the closed state.
One-handed pipe wrench
The one-handed pipe wrench can be clearly differentiated from the common pipe wrench in terms of design. These are self-contained pliers, in the main arm of which there is a small, resiliently mounted second arm, which, similar to the usual pipe wrench, can be adjusted to the desired mouth width with an adjusting screw. The resilient mounting allows a ratchet-like operation, because the jaws press firmly against the tube when tightened and open automatically when the handle is lifted (one-handed operation). Foldable ring ratchet wrenches work similarly for a certain hexagon size .