As the name suggests, Pipe Wrenches are designed to grip round pipes or similar items that a conventional spanner cannot be used on.
Various designs for the gripping mechanism have been developed but all are based on the teeth on the jaws tightening on the item to be held.
These are a standard item for plumbers and gasfitters though they are useful for gripping any item that a conventional spanner cannot be used on. The greatest limitation is that the teeth tend to damage the surface of the item gripped making them unsuitable where appearance is important.
"Handcuff" Wrench - Raglan Tool & Eng. Co., Sydney - came in 2 sizes, ¼" to 1¼" & ½" to 2½".
Dowidat made at least two types of wrench - this Stilson type and open ended spanners.
Wiles, made in Australia
Wiles, made in Australia, close-up of the mark.