Fluid Transients

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What are Fluid Transients?

Fluid transients, often referred to as waterhammer or pressure surges, occur during planned or unplanned changes to a fluid system’s operation and lead to potentially hazardous and rapid changes of pressure and flow.  These fluctuations occur for all industries that utilize pipelines or networks to transport liquids. The most common causes of significant hydraulic transients are:

  • Unplanned power failure leading to pump trip
  • Emergency shutdowns requiring rapid valve closures
  • Changeover operations that bring additional pumps online or redirect the flow path
  • Resonance resulting from cyclically behaving equipment such as positive displacement pumps

Contact us to utilize our domain expertise

PMTG will help you create a unique surge protection strategy using traditional devices and novel system exploitations to comprehensively safeguard your system from hydraulic transients.

Purple Mountain Technology Group is uniquely positioned to provide you the best possible hydraulic transient analysis. As the sister company of Applied Flow Technology, the makers of AFT Impulse, we have a deep understanding of the development of the software and the fundamentals of hydraulic transient analysis.

Transient flow analysis modeling services:

Verify maximum and minimum transient pressures

Specify and size surge mitigation equipment such as

  • Bladder surge vessels
  • Surge relief valves
  • Pilot-operated relief valves
  • Burst or rupture disks
  • Surge tanks
  • Pump station recirculation valves
  • Pump flywheels
  • Surge anticipating valves
  • Air release, air and vacuum valves, and combination valves including 3-stage valves

Specify check valves based on their dynamic closing characteristics and size them for your system to prevent hazardous check valve slam

Specify minimum valve closure times

Let our extensive experience help you.

Transient events we can help you avoid:

  • Ruptures or permanently deformed piping
  • Breaks in seals or leaks that lead to environmental damage, wastage of product, or fire hazard
  • Collapsed piping from vacuum pressures
  • Contaminated water supply lines upon vacuum pressures that pull contaminants in from the environment
  • Reversal of flow that can slam check valves or damage rotating equipment such as pumps
  • Unbalanced hydraulic forces that can damage pipe supports, joints, or other nearby equipment

Standards We Help You Meet:

  • ASME B31.3: Process Piping
    • Stresses produced by occasional loads may be as much as 1.33 times the basic allowable stress
  • AMSE B31.4: Pipeline Transportation Systems for Liquids and Slurries
    • Surge pressures shall not exceed internal design pressure by more than 10%
  • 33 CFR 154.550 – Coast Guard - Facilities Transferring Oil or Hazardous Material in Bulk -Emergency Shutdown
    • Specifies either a 30 second or 60 second stoppage of flow. This will often create a surge pressure that needs to be mitigated
  • 49 CFR 195.406 – US Department of Transportation - Transportation of Hazardous Liquids by Pipeline - Maximum Operating Pressure
    • Specifies maximum operating pressures and states pressures surges may not exceed the maximum operating pressure by more than 110%

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