Can valves, gate valves, dampers, and taps in piping systems be inspected for internal leakage using ultrasound?

Yes. Leaking valves, gate valves, dampers, or taps can generate ultrasonic signals that can be detected using the SONAPHONE and used for condition assessment.

In the case of internal leakage, the medium continues to flow through the valve area even though the valve is closed or intended to provide a tight shut-off. The resulting signals can propagate as structure-borne sound through the valve and connected piping.

How is the inspection performed?

A suitable structure-borne sound sensor is coupled to the valve or to an appropriate measurement point on the piping.

The BS20 or BS40 structure-borne sound sensors can be used for this purpose.

Using the LevelMeter app, the detected ultrasonic signals can be:

• made audible,
• displayed as levels,
• recorded as a level curve, and
• viewed in the spectrogram.

How is internal leakage assessed?

For evaluation, the ultrasonic signals at suitable measurement points are compared. Noticeable differences in the signals can indicate that flow is still present within the closed valve area.

For comparable results, wherever possible, use:

• the same measurement points,
• the same sensor and accessories,
• the same coupling method, and
• comparable operating conditions.

In particular, the pressure and operating condition of the system must be taken into account when interpreting the measurement.