D.H. Lammlein PhD Dissertation - Vanderbilt University

Figure 97: Experimental weld samples were machined from pipe with the external
curvature of a sphere. These samples were halved and then joined in a butted
configuration.
Full penetration welds of butted hemispheres were performed with an internal
supporting ring-anvil. Additionally, welds at 50% penetration depth were made with a
shoulder-less, less, conical tool and without the use of an internal supporting ring-anvil. The
full penetration portion of the experiment was performed with a cupped shoulder,
threaded cylindrical probe tool. The cupped shoulder was designed to mate with the
spherical curvature of the sample surface. When a ring-anvil backing was used, sound
welds with good surface appearance were achieved. It was found that welds made with
the threaded probe tool and without a backing anvil at various penetration depths
(adjusting the length of the probe accordingly) approaching 50% of the material thickness
produced a bead-like protrusion defect, shown in Figure 98, in the interior of the sample
in bead on plate type welds and a more serious protrusion and splitting type defect in
butted hemisphere welds, shown in Figure 99 and Figure 100. During cupped shoulder
(5/8” diameter), threaded probe (0.20” diameter) tool welds made with a backing ring
anvil in a butt weld configuration, on, the material below the probe is deformed by heat and
pressure, and presses against the ring anvil. In this case the ring anvil must be forcibly
removed with a press.
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