Acoustic Induced Vibration (AIV)

Circumferential “Shell” Mode of Vibration

High frequency vibration curtesy of energy institute guideline
High frequency vibration curtesy of energy institute guideline
Low frequency vibration curtesy of energy institute guideline
Low frequency vibration curtesy of energy institute guideline

What is AIV?

• Stress Category: Primary Stress
• Stress Type: Hoop/Circumferential Stress
• Frequency: 500-2500 Hz
• Design Life: Millions of cycles
• Failure Locations: Happens at peak stress (discontinuity) where we have high stress concentrations

Why is AIV more important than years ago?

• Larger pipes and higher D/T ratios
• High pressure drops and flow rates (higher plant output)
• Use of thinner pipe wall thickness (cost savings)
• Use of cheaper piping components (cost savings) etc
 

Typical Sources of AIV

• Relief valves
• PSV bypass valves
• Control valves
• Blow-down valves
• Manual vents
• Compressor recycle valves

AIV High Frequency Circumferential Shell Modes from finite element analysis

Aiv high frequency circumferential shell modes from finite element analysis

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