Expansion bellows are flexible components used in piping systems to absorb thermal expansion, vibrations, and misalignments. They consist of a series of convolutions or folds that allow the bellow to expand and contract with changes in temperature or pressure. This flexibility helps prevent damage to pipes and joints, reduces stress on equipment, and minimizes noise. Expansion bellows are commonly made from materials like stainless steel, rubber, or PTFE, depending on the specific needs of the system, such as temperature range and chemical compatibility.