Vibration Fatigue Analysis

Vibration-Related Services: The E2G Difference

  • E²G specializes in delivering technically superior practical solutions.
  • E²G engineers can typically be on location within 24 hours.
  • E²G offers complete, turnkey solutions. Our engineers will be present, in the field, to interview personnel and to perform all vibration measurements.
  • E²G offers root cause assessments that include metallurgical failure analysis, and advanced analytics, such as computational fluid dynamics (CFD) and Finite Element Stress Analysis (FEA).
  • E²G provides our clients industry leading expertise:
    • E²G is the primary investigator of the new Part 14 (Assessment of Fatigue Damage) in the 2016 Edition of API 579-1/ASME FFS-1.
    • E²G is currently working as a contributing API 579 task group member to add a new part to the next release of API 579 that will include remaining-life fatigue evaluation and screening methods for random piping vibrations.
  • E2G has expert knowledge of ASME construction codes and actively contributes to ASME B31 and Section VIII code committees.
  • E2G uses rigorous methodologies to predict Acoustically Induced Vibration failures and provide remedial actions

 

Vibration Study Benefits

  • Our services:
    • Maximize process flow rates while avoiding flow-induced vibrations from two-phase flow in systems such as heater outlets and heater crossover piping.
    • Detune piping natural frequencies from mechanical excitation sources.
    • Detect the potential for and design system modifications to prevent water hammer events through both simulation and field testing.
  • Piping Support Optimization provides the following:
    • Locations of on-line supports can be optimized based on vibration measurements and mode shape analysis.
    • E2G verifies that all recommended supports are in compliance with ASME B31 while reducing damaging vibration levels.
    • E2G can optimize piping designs to reduce flow-induced turbulence and high-stress, fatigue-prone locations.
  • Multiple sensor technologies (e.g., capacitive triaxial accelerometers, laser displacement sensors, and dynamic pressure transducers) can be used for high-risk scenarios.
  • Fatigue analysis provides the following:
    • Probabilistically approximated remaining life due to fatigue-induced damage.
    • Detailed guidance of NDE inspection by focusing on locations susceptible to highest vibration damage.

 

Example of Screening Assessment

 
Vibrations-2
 

Random Vibrations Require Special Expertise

As opposed to vibration in rotating equipment, piping vibrations are typically random and can even be non-Gaussian broad banded. These vibrations drastically differ from constant amplitude or multimodal vibrations typically seen in rotating equipment.

 

Practitioners can easily misuse the popular industry-accepted screening curves (i.e., The Energy Institute (EI) Velocity Screening Curves from the document “Guidelines for the Avoidance of Vibration-Induced Fatigue Failure in Process Pipework) to assess random piping vibration. The curves were developed based on constant amplitude loading of small bore piping connections. Moreover, the screening curves contain an infinite life “endurance” limit concept for vibrations below the concern limit. Vibration specialists should be aware that misuse of the curves may result in non-conservative, high-risk conclusions. In the below plot, the Energy Institute Piping Vibration Screening Curves are plotted on a linear amplitude scale.

 
 
Vibration Velocity Spectrum
 

E2G’s Data Collection System

The hardware and software used in E2G’s data collection system are fully customizable and expandable to meet any client’s needs. A 24-channel system (shown below) is capable of using accelerometers, displacement sensors, transient pressure gauges, and strain gauges.
 
 
PipingVibrations Image
 

Modeling Flow-Induced Vibration Using Computational Fluid Dynamics (CFD)

Computational fluid dynamics (CFD) analysis provides valuable insight into the sources and locations of flow-induced turbulence and allows for cost-effective design iterations to mitigate vibrations. Additionally, computational fluid dynamics (CFD) is a valuable tool to support root cause analysis. The simulation results below highlight the expected reduction in pressure fluctuations caused by the recommended design change. The simulation below was developed to understand the source of the vibrations and to help prevent future failures of downstream expansion joints.
 
Vibrations-2
 
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