Transient studies that show how high and how low pressures go when pumps trip or start and valves close, and what it takes, if anything, to keep them within limits.
Discuss your system
Steady-state numbers can look fine while a single pump trip sends a pressure wave through the line that exceeds the pipe rating or pulls a vacuum at a high point. Most surge problems only show up when the flow changes quickly.
Transient models are built in AFT Impulse, often starting from the steady-state model of the same system.
Pump trips, pump starts, valve closures, emergency shutdowns and, where it matters, pipeline rupture.
Maximum and minimum pressures along the line, checked against allowable limits, with cavitation and column separation identified.
Air/vacuum valves, surge vessels, check valves and valve closure rates, sized only where the results call for them.
Pipelines, cooling-water systems, pump stations and force mains, and industrial process piping.
Several transient scenarios were run on a condenser cooling-water system, including pump trips, pump starts and valve closures. Air/vacuum breaker valves were sized for locations near the condensers and the pump discharge valve, keeping transient pressures within the maximum and minimum allowable limits.
Work performed by our team members before FSPG, shown as project experience.
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A new pump, a faster-acting valve or a revised shutdown sequence is the cheapest time to check transients, before anything is installed.
Further reading: Applying Valve Closure Concepts to Complex Process Piping Systems, Pumps & Systems, December 2022
Discuss your systemA rapid change in flow velocity, most often a pump trip or a fast valve closure, sends a pressure wave along the liquid column. How large the surge gets depends on how quickly the velocity changes, the length of the line and the pipe material.
When a pipeline or pump station is being designed, when pumps, valves or control logic change on an existing system, or when a system already shows signs of transients such as banging, pipe movement or damaged supports.
No. On one island energy project the analysis showed the system could withstand brief low-pressure events at its high point after a pump trip, so added surge equipment was found unnecessary.
A transient model, results for each scenario showing maximum and minimum pressures against the allowable limits, and recommendations on mitigation where it is needed, written up in a report.
Not sure whether your system needs a transient study? Describe it and the operating change you have in mind.
Discuss your system