What is Expansion Bellows?

The bellows are tube with corrugations. There are different sizes and different materials. The small one can be use in Meters, while the big once can be used in engines of equipment like earth moving equipment, submarine, mining machine etc. We have a special article on the knowledge of bellows. Today we are talking about the normal big expansion bellows used in engines.

There are 3 points: working pressure, working temperature, working circumstance.

The types can be different due to the different situations.

The expansion bellows types can be with outer braid, inner sleeves, flanges or end tubes.

The normal material can be SS304, SS321, SS316L.

The normal bellow thickness can be 0.3x2 layers, 0.4x2 layers, 0.6x1 layers etc.

For engines with high working pressure: the bellow wall thickness can be like 0.4x2layers, or even thicker 0.5x2 layers. Or it also can be with outer braids, thick flanges and end tubes. In some cases, there are tie rods for the delivery consideration. Once installed, the tie rods shall be removed.

For engines with high working temperature: SS304 may crack when the working temperature continuously be higher than 450℃. SS316L works similar as SS304, but has better performance of corrosion resistance under high temperature. In actual working temperature continuously higher than 650℃, better to use SS321, then to avoid the bellow crack. The inner sleeves also can be helpful.

For engines with no special working temperature nor working temperature, it can be the simple bellows only. The simple flanges and end tube can be helpful for welding.

For engines used in the corrosive and rusting environment, eg. the ship, submarine, SS316L is the better choice.

In above situations, the high temperature is the most common case for the expansion bellows used in the engine. Especially for the high-way offer equipment, like the earth moving equipment, mining machine.

The expansion bellows are always made according to the customized drawings. The tools shall be developed accordingly. Once drawing confirmed, the samples can be arranged for test.

The expansion bellows shall be 100% tested before the delivery. The inspection includes appearance check, measurement check and pressure test.

Inquiries about the expansion bellows are welcomed.