Section 417F describes briefly four methods of tube-to-tubesheet attachment, namely roller expansion, fusion welding (outer and inner face), explosive expansion, and explosive welding. This section provides additional information concerning fusion welding, explosive expansion, and explosive welding, together with a description of hydraulic expansion.

The fusion welding processes described are shielded metal are, gas tungsten are (TIG), metal inert gas (MIG), plasma are, and electron beam. Typical weld preparations used with these processes are given, together with fabrication requirements such as preparation, assembly, preheat, postweld heat treatment, and testing.

The fundamentals of explosive welding are given, followed by a description of the various techniques available for explosive expansion and welding. Explosive techniques are described for the plugging of leaking tubes or attachments and also the insertion of sleeves to repair tubes that have been damaged by erosion inside the inlet tubesheet.

The principles of hydraulic expansion are not new, but only in recent years has reliable equipment become available. The system must be compact, lightweight, safe, and reliable and must provide repeatability over a long period, but it must also contain the high hydraulic pressure required to make successful expansions. The advantages of hydraulic expansion over roller expansion are described, followed by a description of the process, the equipment required, and its limitations and developments.