Non-Intrusive Acoustic Valve
Inspection (NAVI)

Non-Intrusive Acoustic Valve Inspection (NAVI)


Non-Intrusive Acoustic Valve Inspection (NAVI) system developed by Maintenance Measure Controle (France) in 1989. This offers non-intrusive inspection service via acoustic technology to identify condition of various valves type and applications while providing leak severity assessment as well as quantification of leak rate.

Passing valves can become a major safety risk when Isolation of a system is not possible during critical times such as Emergency Shutdown. Passing valves can also become the main cause for Loss of production as well as environmental related issues leads by unnecessary flaring.

Our NAVI system is simple, quick and non-intrusive. Using rugged, intrinsically-safe equipment with digital signal analyser for data acquisition. Full data analysis will be processed by a NAVI level 2 operator which had undergo principal training and met competency hours.

Our equipment is sent for calibration yearly to ensure result is of highest level of accuracy.


Contains test plan that suits different valve arrangements or line-up
Unique database for each inspection site or location
Historical database for valves condition
Stores unlimited number of readings
Data can be transferred to notebook or desktop PC via USB

Working Principle

Our Non-Intrusive Acoustic Valve Inspection system works based on the acoustic characteristic of fluid flow through a valve.

A tight valve makes a very little noise

A passing valve (which is equivalent to partially open valve) creates turbulent flow and generates high level of acoustic signal. The acoustic emission is then transmitted into the valve body.

By comparing these two signals, conclusion can be made to determine the internal condition of the valve.

  • Test requirement:
  • Valve in fully closed condition.
  • There is a significant differential pressure across the valve.