Amex-10 Pipe Joint Sealing System
Balmore Road, Glasgow

The use of innovative products within the utilities industry is not new. However, it requires the utility company and its framework contractors to have open minds and commit to collaborative learning, in order to deliver the best all-round solution for the project stakeholders.

This project was to repair 16 joints on 4No, 24” concrete lined steel potable water trunk main pipes, via a no-dig option, as it crossed over a major Glasgow rail spur just outside the city centre.

The normal repair option for this problem would be to close the road for a prolonged period of time, disturbing motorists, public transport systems and pedestrians for weeks. Also, there would be major disruption to an important local railway line requiring costly rail possessions and reduced off-peak working hours, excavations that would risk utility strikes, purchasing new pipes, virgin aggregate and bedding materials, blacktop surfacing, as well as other costly processes that would be involved with a project of this significance. The whole project would have a massive carbon footprint.

However, leading UK water utility provider Scottish Water, challenged its extensive supply chain to find an innovative solution to repair the pipes, whilst minimising local disruption and the carbon footprint, compared to the normal repair process. After reviewing the responses, Amey, a pioneering global engineering and infrastructure contractor, were awarded the contract from Scottish Water to complete the task of repairing the existing pipes by way of the Sanivar Amex-10 Pipe Joint Seal system.

The Amex-10 seals are a no-dig, WRAS approved mechanical seal for use in all water pipes; raw, waste and potable. There are no adhesives, chemicals or resins, only a large EPDM rubber band and two stainless steel locking bands. Spanning the joint, the seal allows a pipeline to move slightly without compromising the integrity of the seal itself. With a minimum life expectancy of 50 years and an operational working pressure of 25bar, the benefits of this system are numerous and deliver many cost savings to the user. Use of the Amex-10 Seals also minimised the duration time of the shutdown on each pipe and therefore reduced any excessive demand being placed on other areas of the water network.

As neither Scottish Water or Amey had used this unique repair technique previously, a rigorous testing and risk assessment process had to be followed to prove its suitability and that the long term benefits claimed would be delivered.

The use of Amex-10 Seals would result in no local disruption whatsoever and offered a safe and quick no-dig solution to repair the joints over the railway lines. No heavy plant was required on the overbridge section and none of the pipes had to be disturbed, allowing the railway to run to timetable and not disrupting members of the public on their daily commutes.

As sole UK and Ireland agents, PMP Utilities Ltd were able to provide over 35 years of experience, examples and customer feedback on the Amex-10 Seals. They have been installed in hundreds of locations across the UK and Ireland by PMP during this time, so the historical performance of the repair system was unquestionable and provided the necessary reassurance to the stakeholders.

Once selected as the preferred repair option, all Scottish Water, Amey and PMP, entered a period of consultation to develop a safe working plan and emergency rescue facilities, which was thoroughly reviewed and validated by an external 3rd party organisation, to ensure the safety of all engineering personnel entering the pipe to install the seals.

When all project RAMS had been written, reviewed and approved, the work on site could begin with the isolation and draining down of the first trunk mains supply pipe. Once all isolations were put in place and the pipe was drained, access to it was provided via a nearby service T Piece, allowing engineers to make a short traverse to the overbridge section and carry out the necessary preparation works.

To ensure the safety of all persons on site being compromised during the installations by a valve being operated in error post closure (not all valves could be locked off due to their location in the road), the Amey project team allocated a two-man team to each valve to guard it and prevent its unauthorised use pre and during site working times.

The first process is to remove the concrete lining to expose the host pipe to which the Amex-10 Seal would be applied to. This ensures a strong mechanical bond and minimises the cross-sectional loss caused by the low 12mm profile of the seal.

After the installation of the 4 Amex-10 Seals in each trunk main, they were left to rest for 12 hours each, and allow any rubber compression to relax. The stainless steel bands are then re-tightened with a hydraulic jack, ensuring the correct amount of torque has been applied, locking them in place within the pipe. As the rubber seal sits beneath the concrete liner level, this allows the edge to be re-profiled and placed under a new screed of concrete, sealing it in place for at least 50 years.

As no chemicals, resins or adhesives are used during the installation of the Amex-10 Seal, once the line is recharged, sample approval is very quick. This allows the main to be returned to public supply very quickly and minimises network demand and potential customer complaints. Also, resins and adhesives will degrade over time, contaminating the water supply and compromising the effectiveness of any repair process that relies on them for structural integrity.

The Amex-10 Joint Seal System is the innovative pipeline rehabilitation system that will reduce project repair costs, carbon footprint and reputational damage. It is suitable for use on all large diameter (>500mm - <3.6m) trunk mains, sewers, culverts, aqueducts and raw water supply pipes from reservoirs and rivers serving the water industry, hydropower, effluent pipelines and municipal assets across the UK and Ireland.

Gerry O’Hara, Scottish Water Project Manager, commented

“Using the PMP Utilities Ltd Amex-10 pipe seals meant that delays from rail possessions were avoided. Also, the water main does need to be pre-cleaned of any tuberculation, this can be done by the operative installing the seals.

Furthermore, damage to the main is reduced as is vibration and forces generated from drag scraping are not transferred through the pipe to the rail-bridge structure. PMP Utilities Ltd are very experienced and competent, high-risk confined space specialists that were ideally placed to understand and control the risks involved in this project.”

David Gethin, Amey Framework Manager for SW Managed Delivery Projects, commented

“Amey had confidence in the PMP Utilities Ltd solution from the numerous successes they have had, that go back over 35 years of undertaking similar repairs.

PMP have now successfully completed the internal joint repairs on 3 of the 4 mains and both Amey and Scottish Water are delighted with the results, together with the skill and expertise and strong focus on quality and H&S from the PMP teams.”

Figure 1 Pre-work team talk to discuss the aims, roles and responsibilities.

Figure 2 Access point in to 600mm potable water trunk main.

Figure 3 Surface preparation of the host pipe – removal of concrete liner to expose the host pipe

Figure 4 Installation of the Amex-10 seal across the pipe joint

Figure 5 The seal has now been 'grouted' in place to restore the pipe lining to the original profile