taft

To taft is to spread the end of a copper or steel tube outward and flat, creating a wide, thin flange. The result is a surface large enough to seat against a fitting, valve flange, or coupling without a separate ferrule. This is done by progressive hammer blows or by pressing the tube end against a shaped mandrel, working the metal cold or warm depending on wall thickness and material.

The process differs from swaging, which compresses a tube inward, and from beading, which raises a bead of metal rather than flattening it radially. Tafting works best on soft metals like half-hard or annealed copper tubing. Hard-drawn tube may crack at the edge if not annealed first. The flange must be even and free of splits to hold pressure; jagged or thin spots are cause for rejection.

Plumbers most often taft connections in low-pressure systems where a simple seal is needed without threading. Radiator connections, drain lines, and some vent stacks use tafted ends. The technique is faster than cutting threads and requires no sealant tape, though a small amount of plumber's dough or hemp may be packed at the joint. The flanged end grips the inside of a taft fitting, or seats flat against a mating surface.

The origin of the term is obscure, but it has been standard in the trades for at least a century. Taft appears in plumbing texts alongside older terms like swedge and flange, suggesting it may derive from a proper name now lost to common use. Regional usage varies; British and Commonwealth plumbers may favor alternative terms like spreading or flaring, though tafting remains current in American practice.