Steel expansion joints can be made from a variety of steel alloys, depending on the conditions (pressure, temperature) in which they will operate and the type of medium that will flow through them.
The working components of the expansion joints, i.e. bellows, are usually made of standard stainless steel and acid-resistant steel: 1.4541(ASI321), 1.4404(AISI316L), 1.4571(AISI316Ti) or 1.4301(AISI304). The other components of the expansion joints, including pipe stubs, flange connectors, tie rods and other accessories, can be made both from the same steels as above and different types of carbon steel alloys, suitable for the conditions in which the expansion joint works.
An extra layer of zinc plating or anti-corrosive paints can be applied on expansion joint components made of carbon steel.
The compensators designed to operate at high temperatures (e.g. above +500°C) are made of alloys with increased temperature resistance, e.g. 1.4828(AISI309), 2.4816/INCONEL 600 or 2.4856/INCONEL 625.
Apart from that, the compensators or just some of their components exposed to the mechanical action of the medium, e.g. abrasion, are often made of alloys, such as Hardox offering increased resistance to this damaging impact.