Saturday, April 4, 2009
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Earlier discussion in "Acoustic Induced Vibration (AIV) Fatigue" has discussed the generation of high frequency acoustic excitation downstream of pressure reducing device and potential of downstream piping failure due to Acoustic Induced Vibration (AIV). Whenever there is pressure drop with mass passing through the valve, internal acoustic energy is generated and transmitted to downstream piping and potentially lead to severe piping excitation, vibration and stresses on downstream piping, in particular at discontinuity section i.e fabricated Tee, small bore connection, welded pipe and pipe support, etc. This acoustic excitation phenomena is generally involve high frequency (more than 1000Hz) acoustic energy. When high frequency acoustic energy is matches with mechanical natural frequency of piping and its component, excitation amplitude is at maximum and lead to increased stress level.
A piping segment may be excited in circumferential and longitudinal mode. Following image shows piping circumferential and longitudinal excitation patterns in different nodal arrangement.
The following video clip shown a piping excitation in circumferential and lead to severe stress level at branch.
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Earlier discussion in "Acoustic Induced Vibration (AIV) Fatigue" has discussed the generation of high frequency acoustic excitation downstream of pressure reducing device and potential of downstream piping failure due to Acoustic Induced Vibration (AIV). Whenever there is pressure drop with mass passing through the valve, internal acoustic energy is generated and transmitted to downstream piping and potentially lead to severe piping excitation, vibration and stresses on downstream piping, in particular at discontinuity section i.e fabricated Tee, small bore connection, welded pipe and pipe support, etc. This acoustic excitation phenomena is generally involve high frequency (more than 1000Hz) acoustic energy. When high frequency acoustic energy is matches with mechanical natural frequency of piping and its component, excitation amplitude is at maximum and lead to increased stress level.A piping segment may be excited in circumferential and longitudinal mode. Following image shows piping circumferential and longitudinal excitation patterns in different nodal arrangement.
The following image display acoustic excitation in 3D.
The following video clip shown a piping excitation in circumferential and lead to severe stress level at branch.
Related Topic
- Acoustic Induced Vibration (AIV) Fatigue
- Sound Power Level (PWL) Prediction from AIV Aspect
- Several Criteria and Constraints for Flare Network - Piping
- Potential Problem associate with Double NRV in Series within a Line
- Flow Element (FE) Upstream or Downstream of Control Valve (CV) ?
- Why a globe valve is located downstream of manual block valve on drain line ?
posted by Webworm, 3:07 PM
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