What the Heck is Acoustic Pipe Inspection? — Part 2

The second part of our series on acoustic pipe inspection technology details the logistics and stresses the need for proper planning.
What the Heck is Acoustic Pipe Inspection? — Part 2
A technician prepares to launch a SmartBall for a fully autonomous traverse through a water pipe. Thousands of feet downstream the SmartBall will be caught and extracted. After capture, it will be sent to manufacturer PureTechnologies to harvest the data.

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In the first part of our “What the Heck is Acoustic Pipe Inspection” series we explored the three latest methods of Acoustic Pipe Inspection, or API. InfoSense manufactures a product designed to inspect partially filled pipe segments – the pipe between a pair of adjacent manholes.

Pure Technologies’ products — the SmartBall and Sahara — perform inspections in pipes filled to capacity with a product that is moving. The flow carries the inspection device through the pipe. All three are proven methods in a variety of locations and applications. Neither company’s product is a suitable replacement for the other, but all enable inspection of pipes that are in-use.

In the second part of this three-part series, we examine predeployment planning, the logistics of insertion and the need to coordinate with the operations department.

The view from inside

To a homeowner, inspecting the inside of a pipe filled with liquid under pressure can be a daunting task and getting the inspection device into and out of the pipe seem like formidable obstacles. Water system professionals, on the other hand, understand how to connect new service taps to larger diameter pipes and to them, this is pretty routine. 

Because the insertion tool for both SmartBall and Sahara bolts directly onto a valved service tap, a detailed system map is crucial when planning which taps and ports to use.  When a needed tap is not in an appropriate place, it must be installed using conventional methods. While the taps may be above or below grade, they must be directly accessible, which means that some excavation may be needed.

For both, the connection taps are identical. SmartBall is deployed and retrieved through two different ports while the Sahara is both introduced and removed through the same port.

Pipe geometry such as bends and turns, as well as tether/umbilical cable length influence access port placement. Sahara tether/umbilical cable is available in lengths up to 5,000 feet. The limitation on a SmartBall inspection is battery life, not a linear measurement.

Port locations and intervening distances are only part of the planning. Both devices are dependent upon a moving liquid, and consultation with the operations staff is appropriate to assure that there is product to move when and where the inspection team needs it to move in order to carry the inspection device with the current.

Depending on daily and special demands, time of day or day of week considerations must be addressed.  For instance, during resupply may be the only time there is water movement if a pipe is used primarily to supply storage tanks or reservoirs, If the scheduled resupply time cannot be changed, then the inspection schedule must be set to coincide with operation routines. If flows cannot be halted at all, then the inspection can be done at any time.

SmartBall inspections are totally autonomous and, once released into the flow, the SmartBall cannot be halted or retrieved. As long as the water is moving, inspection is under way. Data can only be transferred to a computer after the SmartBall is retrieved. The Sahara’s data flows to the control vehicle stationed at the introduction port. There, an operator can monitor progress, hold the device in place or retrieve it. The operator can view the CCTV images and hear the sound track in real time as it is being recorded.

Another crew member on the surface then follows the Sahara at depths up to 30 feet and can pinpoint its position within a few inches. This precision keeps any needed excavations as small as possible and on target.

Sahara data is available and actionable in real time, while the SmartBall’s information must be downloaded and evaluated. Data from either lets the operator determine the magnitude of a leak, while Sahara’s CCTV imagery locates tuberculation and valves and taps — whether known, unknown, illegal or forgotten.

Ear to the ground

The sewer line rapid assessment tool, or SL-RAT, manufactured by InfoSense is designed to inspect pipes with air gaps present. Sanitary and stormwater collection systems — as well as combined flow systems — with manholes at more-or-less regular intervals are prime inspection candidates for this technology.

No special introduction or extraction ports are necessary; a pair of adjacent manholes is all that is needed. Similarly, pipe depth is not an issue. With a manhole opened to daylight, an acoustic device is positioned over the opening. There is no human entry and the equipment never comes into contact with the materials being transported.

With both transmitter and receiver in place and connected, the transmitter “shouts” into the manhole while the receiver listens for the shout. Volume of the received shout, as well as the sound’s travel time, are two of several factors automatically evaluated.

When received, each shout’s unique characteristics are compared to a database of sounds.  A clear air gap with no obstructions has a different segment acoustic fingerprint than the same diameter pipe with intruding roots, creating a series of veils at pipe joints. As pipe constriction increases and flow is affected, similar changes can be detected and different conclusions reached. Fully clogged pipes will not deliver the “shout” to the listening point. These known sounds are benchmarks the software uses to assign condition assessments to each segment. 

Available and actionable in real time, the system can do a segment blockage assessment in less than three minutes, and the SL-RAT lets infrastructure owners quickly identify pipe segments for further investigation or immediate repair. This screening tool does not compete with any other inspection technology. Instead, it helps identify the best next step in a system-wide management plan.

Stay tuned

In the upcoming final installment of this series, we look at how to understanding the gathered acoustic pipe inspection data. You’ll see how that data is presented through the necessary interpretation skills and subsequent data storage and recovery.


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