Hinged Expansion Joints are used to absorb angular movement when it occurs in only one plane. They are also called as Angular Expansion Joints or Hinged Bellows.
Hinged Expansion Joints
Hinged Expansion Joints with Flange Ends
Double Bellows Hinged Expansion Joints with Pipe Ends
The construction of the hinged bellows consists of two hinges connected by a common hinge pin. These hinges are designed to absorb the full pressure thrust of the expansion joint. In addition they can be designed to support the dead weight of the piping and equipment, wind loads and similar external loads.
Since the pressure thrust is absorbed by the joint hinges. only minimal guiding and intermediate anchors are required at each end of the piping system. The bellows reaction force does not act directly up on the anchors. The anchors should be designed to withstand the friction forces at pipe guides, the angular spring rate and friction moment of the hinges.
Double Bellows Hinged Expansion Joints with Flange Ends and Cover
Hinged Expansion Joints
Angular expansion joints are used in sets of two or three at a change in pipe direction. It is recommended to locate them near pipe bends as shown in the figures. Each hinged bellows is restricted to pure angular movement by it’s½ hinges. But a pair of them working in tandem, separated by a length of piping act together to absorb lateral deflection in one plane.
The amount of lateral deflection a hinged expansion joint can accommodate for a given angular movement is directly proportional to the distance between them.To use a pair of hinged bellows effectively the distance between them should be made as large as possible.When only two hinge joints are used as shown in the adjacent figure the piping perpendicular to the hinge segment must deflect to absorb the thermal expansion of the spool containing these angular expansion joints.
Double Bellows Hinged Expansion Joints
Double Universal Hinged Expansion Joints
When the piping in a single plane system is not flexible enough to absorb the thermal expansion of the spool between the hinged joints a system of three hinged expansion joints may be used as shown in the adjacent figure.In this system the combination of the three joints absorbs all the thermal expansion of the piping system and no deflection of the piping is observed. This system produces the lowest possible forces on the intermediate anchors and guides.If the thermal growth in the Piping System occurs in only one plane the use of this joint provides the most efficient solution to absorb the thermal deflections.
Types of Hinged Expansion Joints
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Features
- Absorbs angular movements in only one plane.
- Eliminates pressure thrust loads.
- Positive control over the movements.
- Can support the dead weight of the intermediate piping.
- Prevents torsion on the bellows elements.
- Minimum guiding required.
- Eliminates main anchors.
- Low forces on piping system and adjacent equipments.
- More space required for Hinged Bellows as compared to Axial Expansion Joints.
- Change of pipe direction is required.
- Two or more hinged expansion joints are required to work as a system.