oUmber
15.05.2021 18:16:09
Hot exhaust gas causes pipes to expand. In order to absorb this expansion and protect the piping system against costly cracks that may damage the engine, it is inevitable to install expansion bellows. more
See full version: Should exhaust bellows have an inner liner
Hot exhaust gas causes pipes to expand. In order to absorb this expansion and protect the piping system against costly cracks that may damage the engine, it is inevitable to install expansion bellows. more
Our expansion bellows are type approved by Germanischer Lloyd. If certification from different class is requested it usually poses no significant problem to obtain this at additional cost. more
We assist you in developing the best possible solutions for your individual projects. Please call our experts: +49-4106-80750-33! (Hotline hours 08:00 - 16:00 Central European Time CET.) more
The calculations / designs for the rubber expansion bellows are supplied free of charge. [links]
Flexible connectors are intended to absorb or isolate high frequency, low amplitude engine vibration (fast but small movements) from the rest of the exhaust piping. They are NOT designed to compensate for or absorb pipe expansion, nor are they designed to “make up” for major mis-alignments in the exhaust piping. If the flexible connector between the engine and the silencer seems compressed or “s-shaped” in its idle state, it is not installed correctly. Flexible connectors are made up of flexible hose, which is typically constructed of a single ply of relatively small corrugations that allow the material to move with vibration. The corrugations aren’t designed to compress; over time the flex will fail if it is operated under compression. Likewise, the flexible connector’s inlet and outlet must be aligned. If installed in misaligned piping, it will fail after a short period of time. In general, the optimum length for a flex connector is 18”. Much shorter than this will result in less flex hose, and therefore less ability to absorb vibration. As a point of reference, a typical flex connector will allow approximately 0.25″ deflection on a 12″ length of flex hose. more
Bellows with Flanged Connections more
Flex Connector (shown as “Y” assembly) more
Also worth noting… the corrugations in the flexible section of a flexible connector or a bellows create turbulence, which increases the pressure drop through the device. Bellows can be built with flow liners which smooth-out the flow and make the pressure drop closer to smooth pipe. The liner is welded on one end, with the other end floating, so that the bellows can still compress. Flow liners restrict lateral movement, so a bellows with a liner will not be able to tolerate misalignment or lateral deflection to the same degree as an unlined bellows. [links]
Mike Halloran
Pembroke Pines, FL, USA
I initially thought forum815: Engineering Failures & Disasters may be good too, but it does not have a long history or much traffic, and it tends to focus on disasterous mistakes/results. Take a look and see what you think.
Air expanding through pits and cracks cools the bellows in that area and is easily detected by touch.
Cracks have been detected using this method and they are confined to the 5-7 o'clock position where oxygen and moisture can accumulate between liner and bellows. more
Condenser vacuum is influenced by tube fouling, local air ingress and tube plugging, therefore reverse flow should have been anticipated by the Manufacturer.
Where it is necessary to hold friction losses to a minimum and smooth flow is desired. Where flow velocities are high and could produce resonant vibration of the bellows. Sleeves are recommended when flow velocities exceed the following values:
Water and other Liquids
The liner is a longitudinally welded tube attached at one end to the upstream end connection. The diameter of the liner is small enough that the free, downstream end will not interfere or contact the downstream end connection during lateral or angular deflections. When a standard pipe expansion joint is selected from this catalog with the internal liner accessory, the expected lateral deflection should be stated so that the liner diameter can be properly sized.