Myth: ‘We’ve fitted vibration eliminators so that will be ok’

Fact: Flexible connections allow pipework movement but don’t usually reduce vibration

Flexible connections such as ‘anacondas’ provide some capacity for movement in pipework for purposes such as plant removal/replacement, or if the plant may move for other reasons such as changing load/force. Usually, however, they do not provide any worthwhile vibration isolation for two reasons:

  • Most of the vibrational energy is transmitted by the fluid in the pipework rather than the pipework itself
  • At operating pressure, the ‘flexible’ connection becomes rigid

For example, the fluid in a refrigeration system or at the bottom of a tall building will be at several (or many) bar pressure and will be relatively incompressible at these pressures. This means that any vibrational energy will be transmitted directly by the rigid fluid, rather than compressing the fluid and being absorbed (to some extent) by it.

Measurements on a range of refrigeration pipe systems showed that in some cases the level of vibration was lower on the passive side of an anaconda, in some cases it was unchanged, and in other cases it was higher.

The level of vibration in pipework depends more upon several factors, including the layout of the pipework and how it is supported.