Flanged and Flued vs. Bellows

Flanged and flued vs bellows

Can anyone explain the difference between flanged and flued expansion joints and bellow type expansion joints. ASME sec VIII, Div.1, mandatory appendix 26 talks about bellows expansion joints while, in mandatory appendix 5, it talks about flanged and flued type expansion joints. If both of them are different, then I get confused when I find it written as flanged and flued expansion bellows.


The term you cited “flanged and flued expansion bellows” is generally incorrect. Both flanged and flued joints and bellow joints are expansion joints, but of very different types. The two appendices 5 & 26 illustrate the differences very well, but:

A flanged and flued joint is a relatively thick expansion joint, usually made from two F&F heads. Usually a single convolution, usually the same material as the vessel shell cylinders. Accommodates only a small movement. Simple.

A bellows joint is a relatively thin joint, formed from sheet, many convolutions, usually high alloy or non-ferrous, accommodates larger movements. May be more than one ply. With stub ends, and optional features such as protective covers, shipping bars, etc, more complex

Rule of thumb: If you don’t really need an expansion joint, use a flanged & flued. If you do, use a bellows :)

Above is a snippet.

@SnTMan, Thank you for the thoughtful and clear reply.