1. Definition:

1.1 Hinged Expansion Joint:
The hinged expansion joint contains one bellows and is designed to permit angular rotation (θ) in one plane only, by the use of a pair of pins through hinge plates attached to the expansion joint ends. The hinges and hinge pins must be designed to restrain the thrust of the expansion joint due to internal pressure and extraneous forces, where applicable.
Hinged expansion joints should be used in sets of two or three to function properly for piping system arrangement.

1.2 Gimbal Expansion Joint:
The gimbal expansion joint is designed to permit angular rotation (θ) in any plane by the use of two pairs of hinges affixed to a floating gimbal ring. The gimbal ring, hinges and pins must be designed to restrain the thrust of the expansion joint due to internal pressure and extraneous forces, where applicable.

2. Types of movement:

2.1 Hinged Expansion Joint:
Angular rotation in a single plane.

2.2 Gimbal Expansion Joint:
Angular rotation in multi-plane.

3. Advantages:

3.1 Hinged Expansion Joint:
Angular motion
Positive control over axial movement
Restrains inner pressure thrust forces
Avoids twisting on bellows
Most efficient in absorbing thermal deflections

3.2 Gimbal Expansion Joint:
Absorbs angular rotation
Most efficient in absorbing thermal deflections

4. Principal Uses:

4.1 Hinged Expansion Joint:
Hinged expansion joints are used in sets of two or three to absorb pipe movement in one or more directions in a single plane piping system. A hinged expansion joints is designed to accept full pressure thrust of the expansion joint, and in addition, be designed to support the weight of piping and equipment, absorb thermal loads, wind loads and other external forces. A hinged system permits large movements to be absorbed with minimal anchor forces.

4.2 Gimbal Expansion Joint:
A gimbal expansion joint is designed to permit angular rotation in multi-plane by the use of two pairs of hinges affixed to a common floating gimbal ring. Gimbal expansion joints, like hinged expansion joints, are designed to accept pressure thrust of the expansion joints, and used in pairs, or in conjunction with a hinged joint.