BELLOWS ONLY – NO ENDS

Macroflex supplies bellows capsules-only for variety of markets and applications. They include supplying expansion joint fabricators who weld-on their own fittings as they serve their geographical areas quickly and efficiently.

Sold in bulk quantities to assemblers with an ability to weld thin wall materials, typically through TIG (Tungsten Inert Gas) process. To aid the assembler and prevent ply burning, we can supply bellows end with an external or internal weld band. This is specifically recommended for multi-ply bellows.

Another example is supply of bellows made from exotic materials in critical applications for industrial customers who have the ability to reuse expensive flanges or other types of attachments.

Bellows can be formed from most ductile materials that can be welded by the automatic T.I.G. welding process and result in a homogenous weld structure.

It is imperative that companies specifying and purchasing bellows give thorough consideration to the selection of the bellows material. Due to the fact that media will vary from system to system, and that most media specifications cannot accurately reflect what actually will occur during system operation, it is not appropriate for Macroflex to make specific recommendations regarding bellows material.

If any doubt exists concerning proper material selection for the bellows, we recommend that a metallurgist with the appropriate basic material supplier be consulted. Available bellows materials include:

T304 SS, T304L SS, T316 SS, T316L SS, T321 SS, Inconel 600, Inconel 625, Incoloy 800, Incoloy 825, Monel 400, Hastelloy C276, Titanium.

In order to reduce cost, Macroflex will supply bellows with (ex.) Inconel 600 wetted ply and several middle and outer plies made of lesser grade materials such as stainless steels.

In the design of metal bellows, consideration must be given to:

• Grade of flexibility (spring rate) and service life required
• Corrosion and fluid resistance
• Temperature resistance
• Pressure resistance

Pressure resistance, flexibility and service life is guaranteed by proper bellows design
combining elements such as material used, shape, number and type of corrugations, etc. and can be verified mathematically.

By selecting the right material, we can guarantee resistance to temperature corrosion.

Macroflex metal bellows are designed in accordance with:
• E.J.M.A. (Expansion Joint Manufacturers Association, Inc.)
ASME VIII, Div. I, App. 26
• EN 14917, European Standard. Metal bellows expansion joints for pressure
applications.

Metal bellows can be classified according to different criteria or parameters such as the shape of the convolution, the number of plies used in their construction, the manufacturing method, etc.

In a simplified way, they can be classified as follows:

 

By the method used in their manufacture:
• Hydroformed Bellows
• Expanded mandrel or punch formed
• Rolled

Whether or not they incorporate reinforcing rings:
• Reinforced: with reinforcing rings
• Unreinforced: without reinforcing rings