Production of semi-products of pipe bushings for nuclear power

A procedure is described for the manufacture of semifinished pipe bushings 3200 and 3000 mm long, 400 and 200 mm i.d., which find use in the nuclear power industry for passing tubes through concrete walls of nuclear power plant vaults. An additional advantage of the process is in the fact that two bushings of different inner diameters emerge from double core drilling in a single forged piece, which results in better metal economy as well as in time, tool and power savings. (Z.S.). 1 fig