Securing fresh water for the future in historic Lublin

Lublin is Poland's ninth-largest city — a handsome city, with its Royal Castle and five universities, and some 349,000 inhabitants. But the city has suffered economically.

Before Bulgaria and Romania joined the European Union in 2007, the Lublin region had the lowest per capita gross domestic product rate in the whole of the EU.

And while Lublin has a long and distinguished history, its old steel piping system was similarly historic. In 2014, Lublin and Miejskie Przedsiebiorstwo Wodociagów i Kanalizacji (Waterworks Lublin) had the task of looking after the city's ageing water and sewerage infrastructure.

Plastics played a part in bringing that system up to current needs.

Lublin's water system was planned in the 1970s, during the communist era, and was built to pre-World War II standards. By the early 1990s, when Poland was experiencing massive political change, the water treatment plant at Hajdów fell well short of the standards required by new national — and EU —regulations.

The water treatment plant itself was the recipient of an EU grant, in 2005, and complete modernization of the plant, launched in 2006.

Fast forward eight years, and the pipes supplying fresh water to about half of Lublin's population, about 150,000 people, also needed replacing. With the pipes passing directly through the city center, Waterworks Lublin decided the easiest way to upgrade the steel pipes was to slip a new polyethylene set of pipes inside the existing line, in a process called “re-lining.”

GF Piping Systems, part of Schaffenhausen, Switzerland-based Georg Fischer, along with Polish contractors Molewski Sp. z.o.o. oversaw both the piping and connection systems last year.

Plastic pipes are proven to have a service life of around 100 years, and, compared with metals, are more resistant to corrosion and abrasion, are more lightweight and easier to transport and process.

Molewski used GF Piping Systems' electrofusion couplers to connect the pipes. The GF Elgef Plus system uses a connection of pipes and spigot fittings with active reinforcement — a joining principle unique to the system — which is available for pipe diameters from 355 millimeters to 1,200 millimeters. In Lublin, a diameter of 710 mm, or about 28 inches, was used.

The patented process within the Elgef coupling system is attributed to the manufacturing process itself. During its manufacture, the outer ring of the Elgef coupler is pressed over an inner ring with great force, creating a constant tension on the circumference on the inner ring.

During the fusion process, when the coupler is placed between two pipe sections, this tension is utilized. The heat in the fusion zone, provided by the electrofusion welding machine that plugs into the two recessed ports on the top of the collar, reduces the stiffness of the inner ring. This causes the reinforcement ring to push actively from the outside to the inner ring.

GF Piping Systems said that this means that larger gaps can be closed more quickly and the expansion of the coupler is inhibited. During the cooling process, the constant pressure from the outside makes the coupler shrink onto the pipe.