swing joint

Swing Joints in the Exit Risers

A swing joint is a series of elbows and pipe nipples that allow movement between parts. It's like a universal joint on a car's drive shaft. With steam you probably ran across the term with regard to header piping.  Residential boilers are made up of sections which are bolted together (they look like slices of bread bolted together) The end sections have the steam risers attached to them. If the header that joins these end sections is rigid, when it expands, it puts undesirable  pressure on sections and the joints between the sections. Adding elbows (swing joints ) to the risers allows for movement  and therefore is less likely to cause damage to the boiler. (See attached drawing)

- Rod