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Acoustic Emission Testing
Acoustic Emission Testing (AET) is a reliable method for detecting areas of active deterioration within prestressed concrete cylinder
pipe (PCCP).
By using AET to identify pipes in active distress, operators can monitor:
- Distressed pipes to know which pipes are continuing to deteriorate and to give advance warning if failure is eminent;
- Critical pipes to detect if there are any deteriorating pipes in locations
where a failure would have catastrophic consequences;
- Whole pipelines to determine if there are any pipes in the line that are deteriorating and which sections require further testing;
- Construction zones to learn if the pipeline has been inadvertently damaged.
The Acoustic Emission Testing Application
Acoustic Emission Testing
- works in PCCP pipe of all diameters, including small diameter pipe and sewer force mains;
- installs and operates while the pipeline remains in operation;
- requires no internal access to the pipeline;
- is used under a variety of operating conditions, including steady and unsteady flow conditions;
- records the frequency and number of distress related acoustic events that occur along the monitored pipe section over a defined period of time.
Acoustic Monitoring Principles
Acoustic monitoring takes advantage of the wire embedded in PCCP.
Virtually all corrosion will attack the prestressed wire and when it breaks, the energy can be detected.
Process:
- Prestressing wire breaks or slips generating acoustic energy;
- Energy propagates into water in pipeline;
- Wire-related transient has unique acoustic signature that is detected as it passes the
temporarily installed acoustic sensor;
- Origin is determined by comparing arrival times at each site according to the formula
X1 = (V(T1-T2) + D)/2,
where:
X1 = distance of acoustic event from hydrophone #1
V = velocity of sound in water
T1 = time of arrival of acoustic signal at hydrophone #1
T2 = time of arrival of acoustic signal at hydrophone #2
D = distance between the two hydrophones
The process is illustrated in the following diagram
AET Complements RFEC/TC
AET singles out those pipes that are currently experiencing active distress.
This test measures the frequency and number of distress-related acoustic events that occur along the monitored pipe section over a defined period of time.
A Remote Field Eddy Current / Transformer Coupling (RFEC/TC) inspection establishes the location,
distribution and number of wire breaks at a specific point in time. This test establishes the baseline condition of your pipeline at the time of the inspection.
Combining the baseline wire break information from RFEC/TC with the active deterioration information from AET allows utilities to make informed decisions as to repair, replace or monitor individual pipes in their line.
Armed with this knowledge, water supply system managers can develop a risk management strategy that both controls costs and can extend the safe economic life of their pipeline.
For more information call:
Hugh Leavens, Marketing, at 905-624-1040 x 307
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