Exhaust bellows typically come in either single-ply (single expansion joints) or multi-ply bellows. They are used to isolate engine vibration and absorb thermal expansion in the piping at the same time. While these products seem similar, they are actually quite different. Here is a basic breakdown of exhaust bellows vs flex hose and breaking down exhaust bellows into single-ply and multi-ply bellows.
Multi-Ply Construction
Multi-ply bellows, with their tall convolutions, will provide the ultimate cycle life with the lower spring rates available. These individually designed bellows are constructed will multiple layers of metal. They also generally consist of two to three tubes but can have as many as five tubes depending on the application. Multi-ply bellows also have unique vibration dampening characteristics and greater movement capabilities. Most experts highly recommend multi-ply bellows for prime power, emergency generators, marine propulsion engines, and all critical applications.
Single-Ply Construction
Single-ply bellows have a good cycle life and low spring rates because of their design. When the application has limited space, these bellows will provide a company advantage over the flex hose. Single-ply bellows are handcrafted and have a tangent, or neck, to facilitate with welding, which by design, will remove the affected heat zone away from the first convolution.
Diesel Flex Hose
Flex hoses are typically the smartest choice in terms of economic reasons. However, they provide minimal movement capabilities compared to single-ply or multi-ply bellows because they aren’t very flexible. When predictable cycle life is not an issue and you have plenty of space, exhaust flex hoses can be used with satisfactory results. Most often, manufacturers minimize the impact of the affected heat zone on the convolution by ensuring a no-weld undercut. The weld undercut is the number one major cause of premature failure of exhaust flex hoses, so the no-weld undercut makes a huge difference.
There you have it, exhaust bellows vs flex hose fleshed out for you to understand. While the right piece for the job might depend on the specific application, multi-ply bellows are the best option for any job. If you need custom multi-ply bellows for your next project, let the professionals at Triad Bellows help you out today.
