OUR CONVOLUTION TYPES
OUR TECHNICAL EXPERTISE
SFZ offers 4 types of convolutions depending on the application. After selecting the most appropriate convolutions profile in each hypothetical case, our engineering office designs the bellows while seeking the best compromise between pressure resistance and flexibility, while keeping in mind the optimisation of the final cost of teh material.​
U Shaped
This is the most common convolution profile in the domain of bellows. It is perfectly suited when flexibility criteria are predominant and when the operating pressure is moderate.
Toroidal Shape
This is the ideal profile for applications at very high pressures, which require the absorption of an axial movement, such as tubular heat exchangers. Its resistance is due to the absence of bending stress in the side walls of the bellows, which are generally the limiting factor for the conventional U profile.​
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The use of special forged parts, which simultaneously act as hydroforming tools, reinforcements and end fittings, constitutes a more cost-effective solution than conventional reinforced expansion joints .
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Moreover, the low convolutions height considerably reduces the pressure thrust on the tubular plates of the exchangers, especially when compared to flanged and flued type bellows .
Reinforced U Shaped
The U profile with reinforcing rings is an alternative to toroidal bellows. The reinforced U bellows are especially more suited to lateral and angular movements.
Omega ZH Bellows
The Omega ZH bellows were developed by SFZ especially for the LNG (Liquefied Natural Gas) market.
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It is especially suited for the severe constraints found in naval applications, especially the cryogenic temperature, hogging, sagging, fatigue and pressure .
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