ACOUSTIC-INDUCED VIBRATION
Pressure-reducing devices.
High acoustic energy. Fatigue failure prevented.
Acoustic-induced vibration is the highest-consequence vibration failure mode in process piping. We quantify it, assess it, and provide a defensible integrity position.
The Problem
Pressure-reducing devices — control valves, pressure relief valves, letdown stations — generate broadband acoustic energy in the 500 Hz to 2,000 Hz range. This energy propagates through connected piping, exciting shell vibration modes and concentrating dynamic stress at welded discontinuities: branch connections, nozzles, instrument tappings, and small bore piping.
Failure is rapid and catastrophic. Unlike fatigue mechanisms that develop over years, AIV failures at high sound power levels can occur within months of commissioning.
The failure mode is well understood. The assessment is mandated by API 521 (6th Edition) and the Energy Institute AVIFF guidelines. The gap is between awareness and execution — operators who know the risk exists but have not quantified it against their specific piping configurations.
Our Approach
Emveedo's AIV assessment calculates Sound Power Level (PWL) at each pressure-reducing device and evaluates the connected piping system against established fatigue screening criteria. Assessment follows both the Energy Institute AVIFF methodology and the Eisinger / Carucci-Mueller / NORSOK D/t ratio approach, with the more conservative result governing the design recommendation.
For each identified high-risk location, our proprietary analytical workflows are applied to determine dynamic stress levels and remaining fatigue life. Where existing piping cannot be demonstrated as fit for purpose, we provide a specific, costed modification recommendation — not a generic requirement to "consider redesign."
For large process facilities with multiple pressure-reducing devices — gas compression trains, flare headers, pressure control stations — we provide a prioritised risk register that allows operators and EPCs to direct remediation effort where fatigue risk is highest.
What You Get
When You Need This
COMMON QUESTIONS
Frequently Asked Questions
What is acoustic-induced vibration (AIV)?
Acoustic-induced vibration (AIV) is caused by high-frequency acoustic energy generated by pressure-reducing devices such as control valves, restriction orifices, and pressure relief systems. Unlike conventional vibration, AIV can generate extremely high cyclic stresses that lead to rapid fatigue cracking, particularly in gas systems operating at high pressure and high pressure drop.
How is AIV different from flow-induced vibration (FIV)?
Although both mechanisms can result in fatigue failure, they originate from different excitation sources. AIV is driven by acoustic energy generated during pressure reduction, whereas FIV is caused by turbulence, vortex shedding, or unstable flow behaviour. Because the governing physics differ, each mechanism requires its own assessment methodology and acceptance criteria.
When should an AIV assessment be carried out?
AIV assessment should be considered during FEED, detailed design, brownfield modifications, debottlenecking studies, and whenever significant changes are made to pressure relief systems, control valves, restriction orifices, or operating pressures. Early assessment allows high-risk configurations to be addressed before construction or commissioning.
Which standards are used for AIV assessment?
Our assessments are primarily based on Energy Institute EI 3160 guidance, supported by recognised international engineering standards and established industry practice. Where project-specific requirements apply, these are incorporated into the assessment methodology to provide a technically robust and fully traceable integrity assessment.
What happens if an AIV assessment identifies a high-risk location?
Where elevated risk is identified, we determine the governing acoustic excitation mechanism and evaluate practical mitigation measures. These may include geometry modifications, reinforcement, support improvements, pressure reduction strategies, or changes to piping configuration to reduce the likelihood of vibration-induced fatigue failure.
Can AIV be eliminated by increasing pipe supports?
Not necessarily. Additional supports may reduce structural response but often do not address the root cause of acoustic excitation. Effective mitigation requires understanding both the acoustic source and the structural behaviour of the piping system to ensure that modifications reduce risk rather than simply relocate it.
Related Expertise
Piping Stress Analysis
Independent stress analysis for new design, brownfield modifications, and life extension assessments.
Learn more →Flow-Induced Vibration Assessment
FIV screening and detailed fatigue analysis for centrifugal compressor systems and high-velocity pipework.
Learn more →Small Bore Connection Screening
Rapid assessment of small bore connections for vibration and fatigue risk.
Learn more →The EI AVIFF Guideline
Energy Institute Guidelines for the Avoidance of Vibration Induced Fatigue Failure in Process Pipework.
Learn more →