This product is commonly known as fishing tool / recovery taps by drilling crew.
A worn rod or casing is likely to fracture at the thread coupling and the string below the faulty rod or casing will then remain in the hole. Fishing tools like bell taps and rod recovery taps are used to recover the broken string. Since the fishing tools have a tapered thread that catches the end of the fractured rod or casing or coupling.
Fishing tools / recovery taps are manufactured in right hand thread as well as left hand thread. Both male and female fishing tool / recovery taps are manufactured.
Male and female fishing tool / recovery tap have water ways (flutes) on them so that water can reach throughout the length of the fishing tap. Universal Engineering Works uses high quality material and these are hardened for long life.
UEW manufacture the following Fishing Tools:
Picture of a recovery tap: picture name: fishing tool