Innovative materials help to supply clean drinking water

Rush renewal

In London, 900 million liters of drinking water leak into the ground every day, or about 100 liters per person.All over the world, enormous amounts of fresh drinking water leak into the ground every day. Why? Because of corroded pipes. With raw materials from Bayer MaterialScience, pipes can now be renovated quickly and easily. Great Britain is pioneering the application of this new technology.
For the 1.5 billion people in this world who have no access to clean drinking water, it must sound like a cruel joke: in greater London alone, some 900 million liters of water are lost every day through old, leaky pipes. The problem, however, is not restricted to London: all over Great Britain, one in five liters of drinking water disappears somewhere along its journey between source and consumer.

Some 15,000 kilometers of pipe in the United Kingdom need to be renewed. But leaks are just one problem. Another is the deposits that have formed on the inside walls of the pipes over many decades. In many instances, the deposits are several centimeters thick. They not only prevent the water from flowing freely, but also are the origin of the foul, rusty water coming out of numerous taps.

But if things go according to a regulation issued by the European Union, this murky situation will soon be cleared up: starting in 2010, water utilities must supply their customers with absolutely clear drinking water. For this reason, Great Britain is working all out to renovate its water supply system, and it’s no easy task, because most of the main supply lines run under buildings and streets and therefore are difficult to access.

But specialists always seem to find a way to get underground, for example through gaps between buildings. They dig their way down to a pipe, open it up and run cleaning devices inside. After such an intense cleaning, even the leaky inside walls can be re-coated and sealed.

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Something old, something new: Water flowing through broken down, corroded pipes not only leaks out, it also gets contaminated, meaning that the water coming out of an end consumer’s tap is often reddish and rusty. Coatings up to 5 mm thick inside the cleaned pipes protect drinking water.

Innovative coating system gives old pipes new support and puts a stop to water loss
This type of renewal is an interesting alternative to the conventional pipe-in-pipe method, where new plastic tubes are inserted into old pipes made of concrete or steel. The disadvantages associated with this existing solution are obvious: if the diameter is to remain the same, the old pipe must be milled out from the inside and then expanded with a wedge. The method does costly damage to the area around a pipe and, what’s more, all of the connections branching off a main line subsequently have to be hooked up and sealed from the outside. Conventional epoxy resin coatings, on the other hand, are only suitable for quick renewal to a certain extent, because they cure very slowly and are virtually unusable in cold weather. In view of the requirements imposed by OFWAT, the British Office of Water Services, and the extent of the renovation work, the United Kingdom was in desperate need of fast and efficient solutions. A new product developed by Bayer MaterialScience (BMS) came along at just the right time: the newcomer is a low-viscosity member of the Desmodur N line. It is processed by E. Wood, a medium-sized enterprise based in Northallerton, North Yorkshire. The specialists at E. Wood combine the BMS product with a chemical reaction partner to obtain a two-component system that is applied directly to the inside walls of the pipes by a rotating spray head. To perform the task, the robotic spray system is mounted on a carriage and pulled through the pipes to coat the inside walls.

Dr. Malte Homann, corrosion protection specialist at BMS, describes the system’s favorable properties: “It’s so pumpable that it can easily be transported through a tube hundreds of meters into a pipe and sprayed on the walls. In addition, it cures even at low temperatures.” Another important aspect for application of the coating material is its compliance with strict regulations for products used in drinking water pipes. But not every water main can be renovated so easily. Some are so decayed that it won’t be long before they disintegrate entirely. “That’s why E. Wood was looking for a component that produces a stable, self-supporting coating,” Homann explains. The result of its search is a new aliphatic Desmodur grade providing high ductility in the cured state. Tests with the product have shown that a coating just three millimeters thick can serve as a pipe itself. It remains intact even if the original pipe falls apart around it.

The current objective is to modify the formulation so that it can also be used to renew corroded gas lines

Today, the British company is collaborating with eight of the ten largest water utilities in the country. Hundreds of kilometers of pipeline in Great Britain have been coated and renewed. But the water utility companies on the island are not the only ones relying on the solution from E. Wood and Bayer MaterialScience. “Other countries have similar problems,” says Homann. The new coating system is being put to use in Ireland, France, Spain, Russia and Norway; initial pilot projects are underway in the Brazilian mega-city of São Paulo; and the groundwork is being laid for market launch of the product in China, Malaysia and India. In the meantime, work in the development laboratories goes on. The current objective is to modify the formulation so that it can also be used to renew corroded gas lines. This job presents a different challenge for the specialists. Malte Homann: “Gas lines require coatings with special barrier properties and a very smooth surface.”

In England, the gas grid operator Transco is testing the new systems in partnership with none other than E. Wood. “Our new products are in their infancy and we still have a lot to do. But we’re very confident we will meet this objective as well,” says Homann. The team is motivated by the great response to its successful drinking water projects. In 2006, E. Wood – and thus also BMS – was distinguished with the “Queen’s Award for Enterprise” in the “Innovation” category, in recognition of its latest product. Queen Elizabeth II, however, cannot enjoy the advantages of the system, because the water service lines to Buckingham Palace have yet to be renovated!