Below Water, Yet Above Standard

Dec 1, 2015 10:00 AM

In Summer 2014 GF Piping Systems supported the water company of Sardinia in fixing an underwater wastewater line. The steel pipe was repaired with MULTI/JOINT 3000 Plus fittings which met the high requirements of the harsh environment.

GF WAGA coupling

Just southwest of the coast of Sardinia you find the small island Isola di San Pietro. Almost all of the inhabitants live in the town Carloforte. The water treatment plant of the water company Abbanoa S.p.A. is located in this town as well. All sewage and wastewater of the island is transported to this water treatment plant. After the sewage and wastewater have been processed, the treated water is discharged into the sea. This is done via a two kilometer long steel pipe line with an outer diameter of 429mm. The pipes lay at the bottom of the sea at a depth of 15 to 20 meters. In order to keep the pipes on the seabed, concrete anchors have been used on various locations.

In July 2014 a part of the pipe line came loose from the seabed. Problems with the concrete anchors, in combination with air in the pipe line, caused parts of the pipes to break. As a result those parts floated on the water. The floating pipes needed to be removed as soon as possible to prevent accidents with boats and jet skis. Afterwards the damaged pipe line needed to be repaired as well. But on the seabed not just any fitting can be used. Therefore Abbanoa S.p.A. had clear requirements for the fittings to realize this specific repair. Not only had the fittings to compensate the difference in the alignment of the pipes. An end load restraint fitting with a highly corrosion resistant coating was needed to withstand the harsh seawater. Specially trained divers had to do the installation. Furthermore the fittings had to be delivered quickly.

To make these connections possible GF Piping Systems MULTI/JOINT 3000 Plus couplings in the size DN400 were used. Using thrust blocks or other anchoring materials to secure the connection was not necessary. The nominal angularity of eight degrees per coupling side compensated for the misalignment of the pipes below sea level.

Besides a good product, the organization behind the product needs to be on a high level as well. Georg Fischer S.p.A. responded quickly and effectively to that challenge. A quick delivery was possible, because the fittings were on stock in the distribution centre of Georg Fischer S.p.A. All requested certificates and a clear user manual could be provided on short notice as well. This gave the water company Abbanoa S.p.A. the necessary peace of mind that everything would go well.

In September 2014 a team of divers from a contractor who is specialized in working below sea level, came to Carloforte. To be able to install the couplings, the pipes were lifted slightly off the seabed by using special balloons to enable the divers to slide the couplings over the pipes.

Short delivery times, most professional service and a perfectly suited product helped to face the challenging task of repairing a pipe below sea level as good as possible.

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Attila Albert

Attila Albert
Public Relations & Communication
Georg Fischer Piping Systems Ltd.
Ebnatstrasse 111
8201 Schaffhausen
Switzerland

attila dot albert #at# georgfischer dot com