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Practical engineering guide

Specifying negative pressure wave leak detection

NPW uses a pressure disturbance travelling along a pipeline when a leak develops. It is one monitoring method; suitability and achievable performance must be evaluated for the particular pipeline and operating conditions.

01

Understand the principle and data requirements

A developing leak can create a negative pressure wave travelling in both directions. Fast pressure measurements capture the event, and arrival-time differences help estimate its position. Results depend on wave propagation, sensor quality and timing. Ordinary low-rate historical trends may not contain the information needed for accurate analysis of the event.

02

Separate leaks from operating transients

Pump and valve operations also produce pressure changes. Analysis must distinguish operating events from suspected leaks while considering branches, product changes and multiphase flow. A slowly developing or existing leak may not provide the same signal as a sudden rupture. Combining NPW with balance-based or model-based monitoring may therefore be appropriate.

03

Make performance part of acceptance

Engineering defines measurement points, dynamic response, synchronisation, communications, data retention and control-room interfaces. Sensitivity, detection time and location accuracy are not universal constants. A pilot recording of real operations helps evaluate assumptions. Also specify acceptable nuisance alarms, behaviour during communication failures and responsibility for operator response.

Expected engineering outputs

  • Assessment of NPW suitability and complementary methods.
  • Measurement, data and operational alarm architecture.
  • Project targets and a safely planned verification programme.
Technical sources and further reading

Reviewed on 18 October 2026. Product limits and applicable requirements are confirmed for each specification.

Before we start

Questions that shape the project.

Can any arbitrarily small leak be guaranteed detectable?

Not in general. Performance depends on the pipeline, operation, instrumentation and algorithm. Limits must be agreed and verified. Results from another installation do not guarantee performance on a new route.

Does an NPW alarm automatically close the pipeline?

Not necessarily. Detection, operator decisions and protective action are different functions. Their interfaces, response procedures and any automatic action require a separately agreed and assessed design.

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