The double hinged expansion joints are made of one double bellow element fitted with welding ends plus a system of articulated supports which allow for angular movement in one plane only. The hinge mechanism is designed to accept full pressure thrust.

These units do not allow axial movement however, some types of hinge systems can be provided with holes for the hinge pin that are slotted to allow limited axial displacement. These “slotted hinge” types can not resist the pressure thrust forces and therefore proper anchorage must be provided.

Hinged Expansion Jointed are usually used in a set of two or three, to absorb lateral deflection in one or more direction in a single plane piping system. The Joint in such system is restricted to pure angular rotation by its hinges. Each pair of hinged Expansion Joints, separated by a segment of piping, will act in unison to absorb lateral deflection in much the same manner as a swing or universal Expansion Joint in a single plane application. For a given angular rotation of the individual Expansion Joints, the amount of lateral deflection that a pair of hinged Expansion Joints can absorb is directly proportional to the distance between their hinge pins. In order to utilize the expansion joints most efficiency, this distance should be made as large as possible.

Expansion Joint hinges are normally designed to absorb the full pressure thrust of the Expansion Joint and may be designed to support the weight of piping and equipment. Their direction and magnitude must be indicated to the Expansion Joint manufacturer so that the hinges can be adequately designed to withstand these forces.

Features

• Absorbs angular movements in a single plane
  
• Restrains pressure thrust forces
  
• Transmits shear and wind loads
  
• Supports dead weight
  
• Avoid twisting the bellows
  
• No main anchors required