Axial Expansion Joint

This type of extension joint is the simplest and most useful. It is used in areas with little warm developments. The primary advantage of pivotal extension metal bellows is that the stream bearing is bidirectional, in addition to their small size. These bellows are often constructed of SS304L, SS316L, SS316Ti, and SS321. In the event that special requirements arise, they can be manufactured in Inconel and other nickel-based alloys.

Metal bellows with axial expansion should be positioned co-axially with the pipe centerline. This bellows' purpose is to compensate for axial movements. The presence of axial movements allows for the desired cyclic life. Other movements, such as angular or lateral, will have an effect on the cycle life of the Bellows. Expansion joints are typically utilised between straight pipes where movement is parallel to the pipe line's centerline.

SO, IN SHORT, THESE BELLOWS SHOULD BE USED IN THE FOLLOWING CIRCUMSTANCES:

• Straight-line movement compensation
• Although minor lateral/angular movement is possible, it will reduce the cycle life of the expansion joint.
• Bellows are not intended to absorb rotating motion.
• Expansion joints are required due to the line pressure between the pipe systems.
• The best piping system is one that is divided into intermediate stages by metal bellows at each stage.

If the expansion/contraction rate is greater than the capacity of the bellows, two bellows with a centre foot in between can be employed. The axial movements from either end of the pipe are absorbed by the respective bellows, which are situated between the centres of the pipes. It should be noted that in cryogenic applications, the pipe expansion joint will stretch when the piping system contracts.