BOA pioneered the development of the unique Multi-Ply bellows design which proved to be exceptionally effective in absorbing thermal expansion and vibration.

Advantages of BOA’s Multi-Ply Bellows

Flexibility – Thin gauge material is used in the manufacture of multi-ply bellows increasing flexibility and reducing moving stresses. (A diagram of these stresses can be seen at right)

Higher Pressures and Lower Thrust Forces – Greater pressure ratings can be attained with our Multi-Ply construction by increasing the number and/or gauge of the plies without changing the corrugation contour. With conventional joints, the wall thickness and corrugation height must be increased. 

Advantages of BOA’s Multi-Ply Bellows

Cycle Life – The contour of the thin gauge multi-ply convolution is designed to keep pressure and induced deflection stresses at a minimum. As a result of the low stress level that the bellows experiences during operation, cycle endurance is improved tremendously.

Maximum Travel / Minimum Length – Because of the resulting stresses in a multiply bellows, larger movements are possible within a shorter overall length.

Safety –The multi-ply inner core prevents catastrophic failure. Should a crack occur for any reason, - stress, corrosion, mechanical - the plies, acting as a labyrinth seal constrain the pressure and medium and hold the entire joint intact. A small blister occurs in the outer ply. However, the joint would still perform satisfactorily for many thousand cycles.