Read about START-PROF pipe stress analysis software
Expansion joints can be:
Not Pressure Balanced. Internal pressure creates unbalanced forces acting on caps and convolutions of bellows (a), causing stretch in unrestrained pipelines (b). If the piping is restrained between supports, it cannot expand and passes thrust force onto supports (c). More...
Semi-pressure balanced. Have a special structure, which significantly reduces thrust force. In this structure, the bellows is inside a geometric shell, inside which is a cavity interconnected with the atmosphere. Outside this cavity, the pressure is the same as in the pipe, due to the fact that the bellows is under excess external rather than internal pressure. Thrust force in such expansion joints is around 40% less than in not pressure balanced expansion joints.
Straight Pipe Pressure Balanced. Have a special tie bars and design reducing thrust force to zero
Axial and pressure balanced expansion joints can be modeled using custom expansion joint or untied expansion joint with zero effective area
For pressure balanced expansion joint the thrust area should be changed to zero.
Bent Pipe Pressure Balanced. Have a special tie bars and design reducing thrust force to zero
This type of expansion joint is modeled the same as previous, but it is placed in the node of L-shaped piping.