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Ductile delight

Innovative new pipe laying technology imported from Germany is making waves on the south coast. Mark Hansford reports.

Over the last few months some cunning Germans have been invading the south coast of England. From Lewes to Newmarket to Shoreham, technology not seen before on these shores is quietly being laid beneath the ground in the form of ductile iron pipes.

Nothing new in ductile iron pipes, sure. In fact, some would say using ductile iron is positively passé when suppliers aplenty are lined up with cost effective large diameter plastic reinforced concrete pipes.

But these are different. Made by German specialist Duktus, the 800mm to 1m diameter pipes feature a unique push-fit restraint joint system that makes them quick and easy to install, robust and very cost effective.

“The system is well liked by our pipe layers due to its ease and speed of laying, and the security of the joint system particularly at high test pressures”

Steve Bond, project manager

The pipes were ordered by 4Delivery, a consortium comprising Veolia Water, Costain and MWH. It is carrying out a programme of environmental improvement and water quality schemes for Southern Water until 2015. Southern Water’s overall £1.7bn improvement programme between 2010 and 2015 will ensure drinking water in the south-east remains among the best in Europe. Every day, Southern Water supplies 580M.l of water to customers from 90 water supply works. It flows along more than 13,600km of mains to 1M properties and nearly 2.3M people.

Duktus’ BLS joint is unique as no on-site welding, bolting or external clamping is required. It is a socket joint which operates on the basis of positive interengagement and which is restrained against longitudinal forces.

Force transfer

Forces generated by internal pressure or external loads are transferred along the pipeline and to the surrounding soil. They are transmitted between the individual pipes by means of a weld bead on the spigot end of the pipe or fitting. Via a mechanical lock, the weld bead transmits the forces into the locking chamber in the next pipe.

Extremely high forces which would damage many other joints can be transmitted in this way. Yet it is still flexible, easy and quick to assemble. The joint will accept an angular deflection of up to 5° and a pipe string can thus be laid or pulled in to a radius of only 69m - without fittings and without thrust blocks.

Five minute assembly

Assembly times are five minutes for a 80mm diameter pipe to a maximum of 30 minutes for the 1m diameter size.
4Delivery subcontractor, Winsford-based civil engineering contractor Dragtone is convinced. “Our reputation is built on our professional approach to producing high-quality work, often in difficult locations and conditions. The BLS system is well liked by our pipe layers due to its ease and speed of laying, and the security of the joint system particularly at high test pressures,” says Dragtone project manager Steve Bond. “The system is the quickest and simplest system on the market and we will always recommend it over all others.”

Logistics specialist Burdens supplies Duktus pipes in the UK and works closely with the manufacturer.

Looped contact main

Altogether, the three contracts involved the installation of more than 360m of 1m diameter pipes plus fittings. At Mossy Bottom and Newmarket, the work involved the installation of 1m diameter looped contact mains at the water treatment works to increase the treatment time before the potable water leaves the site and enters the supply.

The scheme at Southover, near Lewes, was similar, involving a twin loop of 1m-diameter contact main to extend the existing 800mm contact main. With ground conditions here difficult, ground beam foundations were piled and the contact main was built above ground and tested to 18bar pressure before commissioning and installation beneath a bund.

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