In-pipe condition assessment technologies for large cast iron water mains



The asset base of water companies includes a trunk main network, which is made up of large diameter pipes that transport large volumes of drinking water, at high pressures, from production/storage sites into local reservoirs and networks. Most of Thames Water’s 3600km trunk main network dates back up to 200 years, is made from cast iron and has diameters as great as 1500mm. Whilst these pipes are very robust and continue to provide excellent service, when they fail catastrophically (burst) the consequences can be serious. Thames Water are constantly trying to increase their understanding of the causes of bursts, to reduce the risks of them occurring, enable appropriate investment in the infrastructure and improve resilience.


Thames Water have conducted significant research into the trunk main failures, which has led to an understanding of some of the contributory causes, such as corrosion – especially in aggressive ground conditions; defects in the original castings; and incurred damage, which could be due to a range of issues, such as ground movements, traffic loading or third-party activities. However, as the trunk mains are mostly buried under major roads, it is very difficult to detect when corrosion or damage have become significant enough to cause a pipe to fail.


Thames Water have an ongoing programme of trunk main inspections, which are mostly opportunistic because of the difficulty, expense, and disruption of excavating down onto pipes, especially on ‘red routes’ into city centres. These inspections allow for one metre lengths of pipe to be examined using non-destructive testing (NDT), but, as corrosion varies greatly, it is difficult to understand the condition of the wider network with this method.


Thames Water require a more comprehensive way of assessing the overall condition of whole trunk mains, made up of many thick cast iron pipes, which will work from the inside of the pipe – without causing damage or affecting the quality of the water that flows through them.
To enable this, Thames Water are constructing test facilities at their Research, Development & Innovation Centre at Kempton Park Water Treatment Works, so that inspection devices can be proven in a safe, above ground environment.


Thames Water wish to collaborate and work with technology companies and research bodies to develop, test and improve in-pipe NDT inspection, scanning and data capture devices. Real samples of cast iron mains will be made available to enable sensor technology to be validated, as a stepping stone to testing of the full in-pipe device in the pipe rig.


The proposals for the pipe rig have already been discussed with other major UK water companies who have endorsed the programme. Together they demonstrate a wider market for new technologies and are working towards mutually agreed testing criteria and knowledge sharing to avoid the need for duplication of trials in different regions.


A contract has been awarded for detailed design and construction of the pipe rig, which is planned to be completed and operational by February 2020.




The preferred output will be a device that will work in water-filled mains and enable hundreds of metres of large cast iron mains to be surveyed from one entry point, with minimal requirement for enabling works to access the main.


Being conscious that this solution may not yet be market ready, proposals for the following solutions will also be considered:


  1. Any in-pipe condition assessment tools that could, with some development, be capable of surveying large diameter thick walled cast-iron mains.
  2. Any in-pipe condition assessment tools that are capable of surveying large diameter thick walled cast-iron
    pipes currently used in other industries.
  3. Any suppliers or research bodies that are interested in developing an in-pipe condition assessment tool that would be capable of surveying large diameter thick walled cast-iron water mains.







The closure date for registering initial interest is 12.02.2019. 


To register initial interest and request an ‘expression of interest’ form, please enter your details online. Alternatively, please call the Energy Innovation Centre on 0151 348 8040 and quote the reference number.


Please note: Specific EOI forms are created for each individual ‘Call for Innovation’ and the matching form will be required to progress any submissions. Office open hours are between 9am and 5pm Monday to Friday.

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