Pipeline measurement system monitors raw water pipeline construction standards

[Case Study, August 2009] -- Pipeline inspection systems such as CCTV are most commonly used to find defects and assess conditions in existing pipelines that have been in service sometimes for many decades. However, currently Oy DigiSewer Productions Ltd (DSP) is involved in a project to ensure that a brand new raw water pipeline is being installed to the highest standards. Using the company's DigiSewer® system, supplied by Painehuuhtelu Oy PTV, DSP is surveying inside the newly laid pipeline section by section.

A length of the raw water pipeline prepared for installation on surface.The raw water pipeline once completed will transfer water from the River Kokemäenjoki at Huittinen in Finland some 100 km to communities with a population of some 300,000 including Turku, Naantali, Raisio and other smaller population centers in the target area of the pipeline. Installing the estimated €50 million, 1,200 mm diameter pipeline is the responsibility of Turun Seudun Vesi Oy, a company owned by 7 cities which will be fed by the pipeline. The cast iron pipe has an internal protective coat of foamed concrete with an external protection layer of pitch or a special compound, the coating used being dependant on the local soil conditions. With a design life of the new pipeline of 100 years it is vital that the internal and external coating of the pipe are in good condition after the installation process is complete.

The DigiSewer® unit in the pipeline during a measuring run.So for its part in the construction process, DSP is using the DigiSewer® system to 'measure' the pipeline internally immediately after the installation of individual pipe section is completed. The pipeline is being installed using open cut techniques with pipe sections being prepared on surface prior to being placed into the trench and buried. Each section is approximately 200 m long.

The purpose of the survey is to determine that neither the pipe joints nor the concrete lining coating within the pipe have been compromised during the installation process, ensuring that the installation quality of the construction is kept to the planned level to achieve the 100 life expectancy.

A view of the survey on screen in the DigiSewer® control van.All data retrieved during the inspection operations is presented to the client using WinCan V8 which can be viewed using WinScan Viewer software. This makes the digital data easy and fast to look at any point in the survey that is required using one or more of the client's own PCs. The DigiSewer® survey also produces an inclination curve which can be printed out separately or viewed directly at same time as the survey data. The digital nature of the data also means that it will be possible to compare surveys taken years apart in order to monitor the condition of the pipeline in future years as the pipeline ages.

Commenting on this new market for the DigiSewer® system, Sakari Kuikka, Director of Oy DigiSewer Productions Ltd said: "To work with DigiSewer® on this kind of 'new pipeline after installation project' is fast, accurate and trustworthy way to control the quality of newly installed pipelines. This gives the survey contractor the possibility to provide more accurate information than with 'normal' CCTV inspection and could also save on costs and provide better profitability."

"DigiSewer® data is very easy and fast to process and enables us to see the quality of the installed pipeline immediately." said Managing Director Jyrki Valtonen, M.Sc. of Turun Seudun Vesi Oy. "This is one part of our security program to reach the planned 100 year life expectancy of this pipeline."

The DigiSewer® System
The DigiSewer® system is designed to be a fast and reliable method of measuring the condition of a pipe and storing this information into a digital format. It provides automatic interpretation of condition data collected to a dimensional accuracy of 1 mm using specially designed data analysis software. This makes the actual survey, data collection and interpretation process operator free. This is achieved because the viewing head of the DigiSewer® system is designed to scan the whole of the inner pipe wall around its full 360° circumference in the one operation, unlike conventional CCTV which requires operator intervention to reposition the camera head to view defects, laterals and joints during a survey.

Unlike with conventional CCTV survey systems, DigiSewer® tends to be referred to as a condition 'measurement' of the pipeline as opposed to an 'inspection'. This is because the data collection achieved with the DigiSewer® system provides a level of accuracy not possible with conventional systems.

An open end of a section of the newly laid 1,200 mm diameter cast iron pipeline awaiting inspection using DigiSewer®.The DigiSewer® measurement equipment normally runs uninterrupted from one manhole to another, but in the case of the new raw water pipeline the survey runs through the most recently laid pipe section. Unlike conventional systems, there is no need for the camera operator to stop the survey equipment where defects are found, to record positional data and condition notes on screen to aid later analysis. This is because the data collected by DigiSewer® is automatically stored millimeter by millimeter onto a CD as the survey progresses without operator intervention, making surveys much quicker to complete.

A typical screen output from the raw water pipeline survey viewed using WinScan Viewer.Using the WinScan Viewer, it is also possible to see five different aspect pictures of one single defect at same time. These include the open view, the front view picture, the complete manhole to manhole section on a single screen, a graphic drawing of the manhole to manhole section showing the plan position of any defect and the inclination curve of the pipeline between the manholes.

Also, as compared to conventional CCTV surveys, the speed at which the collected data can be reviewed by analysts can be as much as five time faster.

August 2009

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