Abstract: A stabilizing attachment for a boring head is provided. The attachment includes a clamp for engaging a rotatable head plate of the boring head, a pair of support arms extending axially of the annular clamping ring, and a transverse plate carried by the support arms at their outer ends. The transverse plate supports a shaft on which is mounted an anti-friction bearing, the outer race of which engages an opening in the wall of a pressure vessel. A bit carried by the head plate of the boring head moves in an annular path to cut a gasket seat about the opening. A method of cutting an annular groove in a wall, utilizing a stabilizing attachment for a boring head which engages in an opening in the wall.

Abstract: Apparatus (10) for imparting protecting compressive stresses to the inside surfaces of a U-shaped heat exchanger tube (12) in order to eliminate or substantially reduce residual tensile stresses within the U-bend region of the U-shaped heat exchanger tube (12) as a result of the fabrication of the U-shaped tube (12) under cold bending techniques comprises a high-speed rotary drive motor (22), flexible drive shafts (28, 30) extending throughout the axial length of the U-bend region of the U-shaped tube (12), and shot-peening flaps (32) having tungsten-carbide shot particles secured thereto. A plurality of epicyclic gear trains (26) are axially spaced along the flexible drive shafts (28, 30) so as to cause the shot-peening flaps (32) to orbit about the interior surface of the U-bend region of the U-shaped tube (12) simultaneously with the high-speed rotary drive of the flexible drive shafts (28, 30).