1864 23 Dec. 411/4 Pipe bender.
a1884 E. H. Knight Suppl. 683/2 Pipe Bender, a mandrel consisting of a strong closely-wound steel helix of uniform exterior diameter and somewhat longer than the pipe to be bent. This is thrust into the pipe and keeps it from being distorted.
1992 Nov. 28/2 Pipe benders are worthwhile for jobs such as central heating where slow bends are preferable to fittings.