Side scan technology for sewer inspection crawlers can speed up the surveillance process while capturing more detail, but to get the most out of this approach, an understanding of the particularities is crucial.
Side-scanning technologies, including Digisewer, an add-on camera for the ROVVER X, make for a more accurate and thorough inspection while requiring less time and expertise from inspection crews. But there are certain limitations, including pipe size and lighting, says Jim Adams, Director of Product Management at Envirosight.
Side-scanning technology relies on software to convert video frames into a flat digital scan. The scan resembles a long strip whose length and width correspond to the length and circumference of the pipe, respectively. These scans capture a level of detail greater than conventional video and make it easier to review and analyze.
Three features differentiate a side-scan technology from traditional video:
- A fish-eye camera lens that provides an ultra-wide view
- Diffuse wide-angle lighting
- A wheel encoder for exact measurement of camera travel
One of the greatest benefits of side-scanning technology is productivity, as it can scan up to 70 feet per minute without the need to stop to pan, tilt or zoom. Rather than the operator analyzing video footage as the crawler moves through the line, visual data is stored in a flat scan and can be viewed later in office and assessed by superintendents and engineers.
But there are limitations.
Adams notes of side-scanning, “As lines get larger, the amount of visual data you gather diminishes and lighting becomes more of a challenge. Corrugated and debris-filled lines also make capturing quality scans a challenge. But smaller, sub-30” lines without excessive foreign matter are the vast majority of what most cities have to inspect, and for this side scanning is a really good way to capture a lot of information very quickly.”
There are several ROVVER X accessories that come with the Digisewer side scan camera that can be helpful when tackling a range of pipe sizes, materials and conditions, says Adams, like electronic lifts, carriages and varying sizes of crawlers and wheel diameters.
“These accessories can help you adapt to different diameter lines, and they swap out quickly without tools,” he says.
Other helpful tricks for making sure you get the most out of side-scanning include monitoring the speed of the crawler; especially in a line with cracks or misaligned joints, slowing down can help. Making sure the cable is tight as it comes off the cable reel is also important, says Adams, as image acquisition is synchronized to cable feed.
“It’s a complete change from the typical way of doing pipeline inspections,” says Adams. “The procedure and the process are a little more sensitive, but the efficiencies are very obvious.”
With side-scanning, there are no gaps in the inspection process, says Adams. “You get 100% of the line, where with the pan and tilt camera, if you’re looking left as you drive, you could miss a defect on the right.”