[DEMO] Metal bellows expansion joints
[DEMO] Hinged expansion joints
Absorbs angular movement in a single plane while restraining pressure thrust through hinge plates and pins.
View productMetal bellows
[DEMO] Hinged expansion joints
Angular movement in one plane, with pressure thrust carried by the hinge hardware rather than by pipe anchors.
A hinged expansion joint absorbs angular movement of up to about 15 degrees in a single plane, while restraining pressure thrust through hinge plates and pins. Units are installed in sets of two or three so that combined rotation accommodates movement along a run without main anchors.
Overview
Angular movement without main anchors
Hinge plates and pins carry the pressure thrust that an unrestrained bellows would transfer to the piping. This removes the requirement for main anchors sized to full thrust load, which is often the deciding factor in a retrofit where existing supports cannot be reinforced.
Because rotation is limited to one plane, hinged units are installed in sets. Two units absorb movement between them; three handle a routed run turning through two directions.
How it works
Thrust restraint through hinge geometry
Pressure acting on the bellows cross-section generates thrust proportional to effective area and internal pressure. In a hinged unit, that load passes through the hinge plates into the adjacent pipework rather than into anchors.
F = P × A_eff
Technical specifications
| Parameter | col1 | col2 | col3 |
|---|---|---|---|
| Nominal diameter DN | 150 | 250 | 400 |
| Design pressure bar | 16 | 16 | 10 |
| Angular movement ° | ±15 | ±12 | ±10 |
| Face to face mm | 300 | 380 | 460 |
| Spring rate Nm/° | 95 | 180 | 340 |
Bellows material options
| Material | Max temp | Notes |
|---|---|---|
| AISI 304 | 550 °C | General service |
| AISI 321 | 750 °C | Stabilised, resists carbide precipitation |
| Inconel 625 | 900 °C | High temperature and corrosive media |
Frequently asked questions
How many hinged joints are needed in a run?
Two or three, depending on the geometry. A pair absorbs lateral movement between them; three units handle movement across two directions of a routed run.
Can a hinged joint absorb axial movement?
No. The hinge hardware restrains axial extension and compression by design. Where axial movement is present, a different configuration is required.