Design and Manufacturing

We design and manufacture single as well as multi-ply metal bellows.The bellows is the basic element of an expansion joint and the following characteristics are given special attention during the bellows design process.


  • Thin gauge  material is used in the manufacture of multi-ply bellows giving enhanced flexibility coupled with lower deflection forces.


Maximum Travel

  •  Maximum axial, lateral and angular movements are optimized considering the lowest possible spring rates and shortest overall length.

Fail-Safe Design

  • Bellows are designed for safety .
  • In case system fail or occurrence of excessive operation conditions.


Cycle Life

  • The contour of the thin gauge multi-ply convolution is designed to minimize pressure and deflection induced stresses .
  • Full load thermal cycles are evaluated with relation to total travel.

Multi-Ply , Multi Wall Laminated Metal Bellows Benefits

The most important feature of FLEXPERT Metal Bellows Expansion joints is the multi-ply/multi-wall laminated bellows structure of the metal bellows elements. The metal bellows are manufactured from multi-wall laminated tube of plies ranging in number from 2 to 20 depending up on diameter and specified operating pressure and other design parameters.
Each of the thin layer acts as a nearly neutral fiber which offer significantly lower resistance to movements in the piping system than a single wall metal bellows. Significantly less force is required for actuating the laminated bellows.


Inset cross section of multiply laminated metal bellows convolution for 0.4mm X 10 plies bellows element

Thus with the same dimensions FLEXPERT multi-wall bellows can accept significantly more movements with ease. The stresses induced on the individual layers of FLEXPERT multi-wall bellows are a fraction of the stresses induced in the single wall bellows of equal thickness. This results in highest possible service life of the FLEXPERT laminated bellows.

  • Increasing Flexibility & Reducing Deflection Forces.
  • Higher Pressures & Lower Thrust Forces
  • Lower Spring Rates & Higher Elasticity.
  • Minimal Installation length due to high Elasticity.
  • Fail safe design due to Multi-Wall Bellows Unit
  • High corrosion resistance can be attained economically for Laminated Bellows.

The Advantages


  • A catastrophic sudden failure is virtually impossible.
  • The multi-ply inner core prevents the instantaneous bursting action.
  • If a crack occurs for reasons like stress, corrosion fatigue failure in the inner or outer plies- the plies in between acting as labyrinth seal contain the pressure and the medium and hold the entire joint intact.
  • A small bubble or blister occurs only in the outer ply.
  • However the joint still performs satisfactorily for many thousands of cycles giving enough time for the procurement of the replacement.


Longer Service Life

  • The inherent advantage of using multiple plies of relatively thin gauge material results in less residual stresses which are introduced at the time of forming the multi-wall bellows element .
  • Also the thinner gauge multiple plies are subjected to less operating stresses compared to a single heavy gauge in operating cycles.
  • For a given duty conditions FLEXPERT laminated bellows have lower built-in and operating stresses which ultimately results in longer life.

Compact Designs

  • Since multi-ply / multi-wall laminated bellows are having more flexibility than conventional bellows they require less length to accommodate a given movement in the pipelines.
  • This makes the assembly of FLEXPERT multi-wall bellows more compact and economical.


Lower Thrust Forces

  • The multi-ply / multi-wall laminated design results in to lower spring rates for a given pressure capacity.
  • Also the effective cross sectional area of multiply laminated metal bellows is less compared to conventional bellows to accommodate a given movement.
  • These two reductions result in to lower forces and moments on the anchors, equipments and guides supporting the piping system.
  • The anchors and guides of the system can be dimensioned significantly smaller and more economically.
  • This increases the life of the connected equipment and raises the reliability of the overall piping system keeping the piping cost to a minimum.

Cost Reduction

  • Because of higher flexibility and movement capacity, a small number of multi-wall bellows joints is sufficient to absorb large displacements compared to conventional thick single wall expansion joints.


No Emergency

  • Even if the inner plies gets damaged the FLEXPERT multi-ply/multi-layer metal bellows does not loose its capacity to perform essential functions.
  • Because of the intact outer plies the ability to resist pressure and the flexibitity of the the expansion joints are retained over a longer time.
  • This gives enough time to replace the joint at the next planned shut-down.

Economical Design for Corrosion Protection

  • In order to reach the desired degree of protection only the ply of the bellows actually in contact with the medium is manufactured from special high corrosion and temperature resistant alloy.
  • The remaining outer plies not in contact with the medium are selected from other economical standard stainless steels.