Elbow Type Pressure balance Expansion Bellows

Pressure Balanced Elbows are metal expansion joints which can consist of a single or double bellows in the flow section, and a balancing bellows of equal area on the backside of the elbow.

Tie rods attach the outboard end of the balancing bellows to the outboard end of the flow bellows. Under pressure, the tie rods are loaded with the pressure thrust force. If the flow bellows compresses in service, the balancing bellows extend the same amount without exposing the adjacent anchors to pressure thrust forces.

However, the spring forces associated with bellows movements are imposed on the adjacent equipment.

A pressure balanced elbow type expansion joint can accept axial compression, axial extension, lateral movements and very limited angular motion.