Successful Premiere for Direct Pipe in the United States

In order to comply with Florida’s increasing demands for energy while ensuring reliable supplies of natural gas, the Florida Gas Transmission Company is currently expanding its pipeline network. The Phase VIII Expansion project adds 772 km (480 miles) of pipeline to the network, allowing to convey more gas from Houston on the Gulf of Mexico to Florida. This additional natural gas is primarily used for electricity generation in local power plants thereby covering the daily power requirements of up to 1 million households.

            The main contractor Sheehan Pipe Line Construction Company commissioned REM Directional Inc. with implementing the requisite crossings for the pipeline installation. So far, horizontal directional drilling or auger drilling technology have been used, based on the respective project requirements. For the crossing under the Highway 70 in Arcadia, the new Herrenknecht Direct Pipe method was used for the first time in the United States. The construction company preferred this solution as the geological layers containing ground water, shells, sand and clay can be safely crossed – in some cases at a depth of only 2.1 m (7 ft) – allowing for an accurate alignment with a horizontal and vertical curve.

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            During the installation process, slurry tunneling with the Herrenknecht Direct Pipe machine, guaranteed the requisite precise pressure control of the tunnel face, preventing settlements or heave on the site surface. The Herrenknecht navigation system U.N.S. with gyro-compass and electronic hydro level keeps the machine on the specified three-dimensional curve with vertical and horizontal curve radii of 914 (3,000 ft) and 1,828 m (6,000 ft), respectively, for a safe and exact course. The Herrenknecht Pipe Thruster is anchored in the launch pit and thrusts the prefabricated pipe string that has been laid in advance. The average thrust force of 15 tons (max. 28 t) is transferred to the Direct Pipe machine ahead. Highway 70 was swiftly and safely underpassed using this award-winning (Iploca Award in 2009) method. Despite the three-dimensional curve, only three drilling days (single shift operation with 12 hours) were required for exact and safe installation of the 215-m (705-ft) pipe string. The Herrenknecht machine reached the target pit as early as Aug. 29, 2010.

After a total of five successful Direct Pipe projects in Germany and the Netherlands, this Herrenknecht innovation has proved itself for the first time in North America where it demonstrated its advantages in full. REM Directional Inc. already has plans to use the Herrenknecht Direct Pipe method again for another 36-in. crossing.

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