Surrounded by sand, ten Volvo PL4611 pipelayers stand alongside one another to carefully lower-in a section of the Bunde-Etzel gas pipeline into the freshly excavated trench.
As the 12 tonne, 1200mm diameter pipe is lowered, a short, sharp, whistle blow carries above the engine noise and the machines’ booms halt.
The whistle belongs to a spread manager standing at the side of the trench, orchestrating the lowering. At his signal the machines move, one by one, along the pipe to lower the next section.
The Bunde-Etzel pipeline in Northern Germany will be 60km long and operable in both directions, between the cavern storage at Etzel and the gas pipeline hub at Bunde – situated on the German-Dutch border.
IVG Caverns, which operates caverns for both crude oil and gas in Etzel, is expanding its storage facilities and the new pipeline is needed to deal with the increasing demand for gas. It is expected to hold 4.5 million Nm3/h.
A new concept
Ghizzoni is the Italian contractor in charge of the project. Ghizzoni was commissioned by Bunde Etzel Pipeline (BEP) to complete the pipeline by mid- 2011, for a contract value of $83 million.
Ghizzoni has been operating in the pipeline industry for 60 years and has extensive experience of constructing and laying cross country pipelines for oil, gas, and water transportation.
Lowering and laying is the sole purpose of the Volvo pipelayers onsite. The machines work tirelessly for eight hours every day, accompanied by ten Volvo EC290BNLC crawler excavators. Generators pump out ground water before the Volvo excavators dig a trench. Then the pipelayers stand in a row and lower sections of the pipeline into the ground.
Water is then pushed through the pipeline to check for leaks, which can be fixed onsite if found, before the trench is covered over.
“The lowering and laying by the Volvo pipelayers is excellent,” says Marco Scazzina, Construction Leader at Ghizzoni. “We can lower a1km long pipe in one go using 10 pipelayers at the same time.”
The Volvo pipelayers are different to the conventional side-boom track-type tractor pipelayer and Ghizzoni was keen to try the new concept. “The boom on the PL4611 can turn 360°, unlike the fixed boom on a normal dozer,” explains Scazzina.
“This provides enormous flexibility, precision and better control for the operator in pipe placement.”
The Volvo PL4611 is based on the Volvo EC460C standard hydraulic excavator design, which makes the machine very versatile.
“It can be disassembled easily and transported quickly, within the hour, by hydraulically lowering the counterweight and removing the track frames,” continues Scazzina. “This is important on such a big project because time is very precious,” he says.
During the project the PL4611 can be transformed into an excavator, by switching the boom for digging equipment, enabling contractors more flexibility onsite.
The boom on the PL4611 is longer than a conventional side-boom track-type tractor pipelayer at 9.2m (30ft), which means the machine can sit back from the trench and avoid the risk of tipping.
“In very wet conditions the risk of slippage is considerable, if not inevitable, when conventional side boom pipelayers are required to work close to the trench,” says Scazzina.
But the PL4611’s boom is mounted inside the track frame, near the machine’s central line, for higher lift capacity and stability and its fixed-track width of 18ft (5.48 m) provides a solid working platform.
“Safety is a priority for Ghizzoni so we want to make sure our machines have the best possible safety features. Volvo provides these features,” he continues.
Visibility is key onsite and the PL4611 has a standard Load Management System which enables the operator to see what he can lift safely depending on the angle of the boom, the position of the cab relative to the tracks and the incline on which the machine is operating.
The machine offers a tipping load capability of 110 tonnes, depending on the terrain.
The boom has a three-stage light indicator system situated at its end, which shows when it reaches load capacity – spanning from green (lowest) to red (capacity).
The standard fully enclosed Volvo Care Cab means the operator has excellent visibility and the boom is asymmetrical so the pipe can be seen at all times, for safe and precise load placement.
Up to the challenge
Building the Bunde-Etzel pipeline is not an easy task, mainly because of the abundance of canals and waterways in
the area.
“The water table is very high – only 50mm below the ground surface – which causes problems in excavation and planning,” says Scazzina. “The pipeline has to pass underneath the Elms River for 1,000 m so we need to be conscious and protect
the environment.”
So after the 22mm thick pipes are welded together they are meticulously tested for leaks.The ground conditions have also caused problems for the contractor.
“The soft soil in the area – a mixture of silt and sand – became very soft during the heavy snowfall we had at the beginning of the year, which caused the machinery to sink,” says Scazzina. “But we continued with the machines and now we are halfway to completion.”
A growing segment
Marco is pleased with his new machines. “Volvo’s new concept could be the future for pipelayers,” he grins. “We are keen to try the Volvo pipelayers on some of our more challenging projects.”
