When joining to metal or to certain other piping materials, or if a PE pipe section capable of disassembly is required, PE flange adapters or stub-ends are available. These items are designed so that one end matches the PE pipe for a butt fusion connection. The opposite end contains a flange that provides structural support, eliminating the need for a stiffener and, with the addition of a metal back-up ring, permits bolting to a similar flanged end connection to another pipe, of various possible materials. Flange adapters differ from stub-ends by their overall length. A flange adapter is longer, allowing it to be clamped in a fusion machine similar to a pipe end.
Flange adapters not requiring fusion to the PE pipe are also available. This fitting combines a flange connection at one end with a mechanical bolt type coupling to the PE pipe at the other end, at which a stiffener is required. Mechanical flange adapters may or may not include a self-restraint to provide restraint against pipe pullout as part of the design.