Angular Expansion Joint

  • Angular Expansion Joint
  • Features & Benefits
  • Expansion Joint Thrust Calculation
  • Expansion Joint Spring Rates

Angular expansion joints (hinged or gimbal type) with one or more molded wide arches are designed to permit angular rotation only, reduce noise and vibration, have a cycle life in the tens of millions, provide access to piping and equipment and relieve pipe and anchor stresses.

Explore Angular Expansion Joint

An angular expansion joint is an axially restrained flexible connector fabricated of synthetic elastomers and fabrics and, if necessary, with metal reinforcements to provide stress relief in piping systems due to thermal and mechanical vibration and/or movements. 

Explore Features & Benefits

Thermal movements along with other external forces and displacements, including ground settlement can quickly exceed allowable pipe and anchor stresses. Rubber expansion joints absorb these stresses and replace them with their own low stiffness (spring rate). 

The inherent flexibility of rubber expansion joints permits almost unlimited flexing to recover from imposed movements, requiring relatively less force to move, thus preventing damage to motion equipment. When expansion joints are installed in the pipeline, the static portion of the thrust is calculated as a product of the area of the inner diameter of the arch of the expansion joint times the maximum pressure that will occur with the line. The result is a force expressed in Newton which causes stress on the adjacent pipeline anchors. 

Angular expansion joints receive one or two pairs of hinge plates connected with pins across the expansion joint axis from flange to flange to take the full pressure thrust so that no thrust is transferred onto adjacent pipeline anchors, guides or equipment anymore.

The spring rate is defined as the force in Newton required to deflect an expansion joint one millimeter in compression and elongation or in lateral direction. For angular movement the spring rate is the force needed in Nm to deflect the expansion joint one degree. 

These forces should be considered only as approximates which may vary with the elastomers and fabrics used in fabrication and depend from the specific construction type.The spring rate for a filled arch type expansion joint is approximately 4 times that of a standard single arch type. This rate is dependent upon the material used in the filled arch section of the expansion joint. The spring rate of a multi-arch type expansion joint is equal to the spring rate for a single arch type divided by the number of arches. Angular expansion joints require in addition to the forces from the bellows stiffness frictional forces which arise in the joint bearings of the hinge or gimbal.

Expansion Joint Spring Rates