In the water supply sector, maintaining the functionality and value of drinking water infrastructure is a major challenge for the coming years. The water suppliers are particularly interested in non-destructive technologies for network inspection to assess the condition of pipelines. The recently published DVGW standard W 492 contains an overview of practical, non-destructive inspection technologies for drinking water pipes and their areas of application.
The inspection of drinking water pipes using camera systems is an innovative approach that the TZW: DVGW-Technologiezentrum Wasser has been working on for several years. As part of its research activities, TZW is working on the DVGW project "OptInspekt", which focuses on camera inspection. For this purpose, TZW has equipped itself with its own inspection system, which has a cable length of 2500 meters. This enables the inspection of significantly longer pipeline sections compared to conventional systems. Over the past two years, numerous inspections have been conducted within the framework of 'OptInspekt' as well as consulting projects for water utilities, gaining valuable knowledge and experience.
Camera inspection procedure - hygiene has top priority
Prior to the inspection, detailed project planning is carried out in accordance with W 492, which takes into account the following points, among others:
- Checking the inspectability by evaluating available pipe information
- Preparation of an inspection schedule
- Risk assessment
- Definition of tasks between the parties involved
Particular attention is paid to hygiene. In accordance with W 492, the system is used exclusively in drinking water applications. All objects that come into contact with the inner pipe surfaces or the water in the pipe are cleaned and disinfected. The cable is continuously disinfected with a special system during operation.
A video is made of the inspection and any anomalies are recorded in a photo protocol. The positioning of anomalies and pipe installations is based on the exact cable length recorded. If required, a comprehensive report with further evaluations is created.
Following pipes have been inspected at various water suppliers:
- Diameter: DN 400 - 1200
- Materials: PE, GGG-Zm, steel
- New pipes and existing pipes
- Empty and filled pipes
Based on previous experience, the following information can be obtained from a camera inspection:
- Condition of the inner surface (Corrosion, roughness, detachment, color, inhomogeneities)
- Pipe geometry
- Deposits
- Gas bubbles
- Foreign matter
- Root ingrowth
- Condition of inliners
- Condition of galvanic anodes
Wide range of applications for quality testing and innovation
Several projects were aimed at checking the quality of new installations and construction measures, with issues such as the sealing of weld seams on steel pipelines or the presence of contamination. In addition, pipelines that had been out of service for some time were also inspected in order to obtain information for a possible recommissioning. In one case, in addition to the camera inspection, an electromagnetic method was also used to record the condition of the pipe wall in order to obtain comprehensive information on the pipeline situation.
In order to expand the range of applications for camera inspection, investigations are currently being carried out as part of the DVGW project "OptInspekt" into the inspection of pressurized pipes and the use of the "water snake" system, which has sensors to detect leaks in addition to the optical system. Read more about the research project here.
The use of camera inspections is an innovative method for the drinking water sector. For water supply companies, it can be an excellent tool for assessing the condition and possibilities for new structural concepts in a detailed and fact-based manner. If you have any questions about the internal inspection of drinking water pipes, please contact TZW.