Double gimbal expansion joints, also known as universal expansion joints or double universal joints, are types of expansion joints used in piping systems to absorb movements in multiple directions. They consist of two sets of hinges or gimbals connected by a central spool or bellows.

Here’s how they work:

1. Two Gimbal Arrangement: The expansion joint consists of two sets of gimbal arrangements, each allowing movement in one plane.

2. Central Spool or Bellows: The gimbal arrangements are connected by a central spool or bellows, which accommodates axial movement, lateral deflection, and angular rotation.

3. Flexibility in Multiple Directions: This design allows for movement in multiple directions, including axial (lengthwise expansion and contraction of the pipe), lateral (side-to-side movement), and angular (rotation around the axis) movements.

4. Materials: Double gimbal expansion joints are typically made from materials like stainless steel, carbon steel, or other alloys suitable for the operating conditions of the piping system.

5. Applications: They are commonly used in piping systems where there are complex movements due to thermal expansion, seismic activity, or other factors. Industries such as petrochemical, power generation, and HVAC often utilize these joints in their piping systems.

6. Maintenance: Proper maintenance is essential to ensure the longevity and efficiency of double gimbal expansion joints. Regular inspection for signs of wear, corrosion, or damage is necessary, and any issues should be addressed promptly to prevent leaks or failure.

Overall, double gimbal expansion joints play a crucial role in maintaining the integrity and functionality of piping systems by accommodating movements and reducing stress on the pipeline components.