The supply of hygienically perfect drinking water always in sufficient quantity and quality and the trouble-free forwarding to the respective end consumers is the sovereign duty of every single water supply company.

To this end the monitoring of the underground pipelines for the inner-city water transport is particularly in focus. With its special inspection technology INSPECTOR SYSTEMS tackled these particular requirements.

In Sakai City / Japan, which is situated in the metropolitan area of Osaka, various pipeline sections of drinking water pipes were inspected. The pipes, which have an inside diameter of 300 mm, are manufactured completely from cast iron and in addition are lined with an inner cement coating.

Mission concerning drinking water in Japan
Mission concerning drinking water in Japan

The Japanese company Kubota acted as customer. One of the largest manufacturers in the world of exactly these internal concrete-coated cast iron pipelines. Sections of approx. 50 to 100 meters were each inspected. Night shifts were scheduled for the work, so that the road traffic would be affected as little as possible.

The SLOFEC inspection robot, which was developed jointly with Kontrolltechnik GmbH, was deployed for this assignment. In combination with the SLOFEC inspection procedure wall thickness reductions can be determined and classified right through a layer of cement with this inspection robot. The SLOFEC procedure is therefore predestined for this type of pipeline.

For the inspection the respective pipeline section was opened at only one place, which was situated in a pit excavated extra for this purpose. The robot was inserted into the pipeline through this created opening and travelled through it up to the end of the section and then back to the insertion point. As a result only one pipeline opening was necessary.

The inspection was performed in a pipeline partially filled with water, because the water is unable to flow away at all places. Cleaning of the inside surface of the pipe before the inspection was not performed.

In parallel to the pipe examination a visual inspection was also performed with a high-resolution camera. The results of the pipeline examination were later verified. Greatly damaged pipe segments were replaced and the results of the SLOFEC inspection were proven based on these pipe segments.

The inspection was a complete success and it was confirmed by our customer Kubota, that all wall thickness reductions and areas of pitting corrosion in the pipeline had been detected with an error tolerance of 15%.

Furthermore the robot was subjected in advance to a qualification in a test section constructed specifically for this purpose with concealed test faults. With this, besides the measuring accuracy and the distinction between inner- and outer corrosion it was verified, that environmental influences such as water inside or outside the pipeline, cement and steel supports do not influence the measuring result.