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How to boldly go where no inspection tool has gone before
Undertaking an inline condition assessment of buried pipelines can make anyone nervous, especially if you’re worried about the consequences of cleaning pigs or inspection tools becoming stuck in your main. There are often many unknowns about the pipeline and the inspection process that can contribute to concerns about tools being impeded by debris or buildup, obstructed by valves or other fittings, or not making it through tight elbows.
However, these concerns can be mitigated with well-planned preparation and a progressive pigging program followed by a gauge pig run. These preliminary steps enable PICA technicians to confidently conduct a SeeSnake pipeline condition assessment, with virtually no risk of tools becoming stuck.
Moreover, the high-resolution data collected by SeeSnake can help extend operational life of aging pipelines, reduce replacement costs and dramatically lower the risk of catastrophic failure.
Planning and preparation build the foundation for successful projects
“PICA has developed a rigorous process to prepare for each condition assessment project and ensure that our tools can make it through the pipelines safely, while collecting high resolution data,” says Dave Russell, President and Founder of the PICA Group of Companies.
Often, several days of planning and preparation precede PICA’s inline condition assessments to ensure that inspections run smoothly.
The first step is to review accurate, as-built drawings, which can help identify where the pipeline construction could present challenges.
After reviewing the drawings, PICA conducts an exploratory process called progressive pigging to remove loose debris (wax, scale, fats, grease, silt and sand). Progressive pigging starts with a pig that’s several inches smaller than the pipeline diameter, followed by passes with progressively larger pigs. Each run works to remove debris and clean the pipe. Not only does progressive pigging clean pipelines, it’s an essential step in assessing if a project can move forward.
Following this process, a gauge pig is run to alert PICA technicians about obstacles or changes in pipe diameter that might cause problems during an inline condition assessment (see photo above). These pigs are fitted with a slotted aluminum disk that becomes distorted if it comes into contact with any obstructions.
Armed with this information, PICA technicians can take appropriate steps to remove or by-pass serious obstructions and select the appropriate size of SeeSnake tool to safely pass through the pipeline.
Once the preliminary steps are complete and the inspection is ready to begin, several aspects of PICA’s tool design and in-field procedures continue to minimize the risk of SeeSnake becoming stuck. For instance,
- Bidirectional tools: SeeSnake tools are capable of traveling in both directions through a pipeline, enabling them to reverse if an impasse is encountered. For runs up to one mile long, a tether is often attached to pull the tool through the pipeline, with a second trailing line that can be used to reverse it if it becomes stuck. In the case of a free-swimming inspection, the direction of water flow can be reversed to push the tool backwards and free it from a tight spot.
- Flexible design: PICA’s SeeSnake tool employs a modular, flexible design that enables it to navigate a wide range of pipe features including 90-degree elbows, tees, valves, mitered elbows, and more.
- Tracking the tool: During an inspection, a technician uses above-ground locators to communicate with the tool and track its progress at pre-determined sites that are usually 1,000 feet apart. Tracking the tool helps to ensure that it’s continuously moving at a rate of about 15 ft/min and its location is accurately synchronized with GPS data.
“Good decisions start with good information,” Russell says. “Good information about how a water or wastewater system has been built informs good decisions about how an inline condition assessment is undertaken.”
Precisely locate and size defects within your water mains
PICA’s SeeSnake tool with remote field technology on board (RFT) identifies the precise location of defects and accurately maps weak spots, even through build up, tuberculation and liners. The information gathered by the SeeSnake can be used by a pipeline owner to confidently decide when specific pipes need to be repaired or replaced.
As the flexible SeeSnake tool makes its way through a pipeline, RFT technology measures the actual remaining wall thickness to locate areas of wall thinning, pitting, holes and cracks along the entire length of pipeline and around the circumference. By measuring the actual remaining wall thickness, SeeSnake can not only reveal the precise location of defects, but also the degree of wall loss.
Asset managers can use this detailed information to mitigate the potential risk of a pipeline failure and also to establish baseline pipeline conditions or supplement bench models. Some competing inspection technologies only measure the average remaining wall thickness but do not provide high resolution defect dimensions and depth.
Watch this video to learn more about pipeline condition assessments.
Read more about the advantages of measuring actual vs. average wall thickness in metallic pipelines.
Learn more about using SeeSnake for condition assessments of your water and wastewater infrastructure.
Contact us to discuss your inline assessment project.
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