The pressure retaining capability of a bellows is based on the material type and thickness, bellows convolution geometry, and number of convolutions. Bellows design is complex. See the Bellows Design Variable chart on the bottom of the Metal Bellows Cycle Life & Design Variables or on page 12 of the handbook (see Related Download below) to better understand the variables of metal bellows design.
Bellows Squirm results from over pressurization, and/or improper guiding of an installed metal bellows expansion joint. Squirm leads to permanent deformation and/or immediate failure of the bellows.
Knowledge Base Handbook for Metal Bellows Expansion Joints