1. Definition:

1.1 Pressure Balanced Expansion Joint:
A pressure balanced expansion joint produces pressure caused by internal force and compression, is designed to absorb axial movement (x-axis) and/or lateral movement (y-axis, z-axis) and by means of whose function by special structure to restrain and balance force instead, rather than the force transferring to the anchors of pipeline.

1.2 In-Line Pressure Balanced Expansion Joint:
An in-line pressure balanced expansion joint is designed to absorb axial movement (x-axis) and/or lateral movement (y-axis, z-axis) which is restraining the pressure thrust by means of tie devices interconnecting the line bellows with outboard compensating bellows also subjected to line pressure. Each bellows set is designed to absorb the axial movement and usually the line bellows will absorb the lateral movement. This type of expansion joint is used in a straight run of piping.

1.3 Elbow Pressure Balanced Expansion joint:
Pressure Balanced Elbows are expansion joints which can consist of a single or double bellows in the flow section, and a balancing bellows of equal area on the back side 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. The flow bellows restrains the balancing bellows pressure thrust loading when balancing forces by means of tie-rods transferring. A pressure balanced elbow type expansion joint can accept axial compression, axial extension, lateral movements and very limited angular motion.

2. Features:
Stable at high pressures
Eliminates pressure thrust
Absorb axial and lateral movements
No volume change
Conserves space