Axial Expansion Joints
This sort of extension joints are the least difficult and most practical joint. It is utilized where little warm developments exist. The prime point of preference of pivotal extension metal bellows is, the bearing of the stream is bidirectional alongside their minimal size. These bellows are generally made in SS304L, SS316L, SS316Ti and SS321. If there should arise an occurrence of extraordinary prerequisites they can be made in Inconel and other nickel based combinations.
Axial expansion metal bellows should be installed co-axially with the pipes centerline. The purpose of this bellows is to compensate axial movements. With the existence of axial movements desired cyclic life can be achieved. If incase there exist other movements like angular or lateral this will affect the cyclic life of Bellows. Generally there expansion joints are used between straight pipes where movement is parallel to the centerline of pipe line.
So in short one should use these bellows in following circumstances:
- • Movement compensation is in straight line.
- • Minute lateral/Angular movement can be adjusted but will affect the cyclic life of the expansion joint.
- • Bellows are not designed to absorb rotary movements.
- • Due to the line pressure between the piping systems numbers of expansion joints are required.
- • The best piping system is the once which is broken between intermediate stages with metal bellows at each stage
In case if the expansion/contraction rate is higher than the bellows capacity 2 Bellows with a center foot in between can be used. There 2 bellows are placed between the center of the pipes so that the axial movements from each ends of pipe can be absorbed by the respective bellows. One should note in case of cryogenic application the pipe expansion joint will be stretched as the piping system will contract.