Successful Premiere For Direct Pipe In The U.S.

December 2010 Vol. 65 No. 12
The Herrenknecht Direct Pipe machine with the coupled pipe in the launch shaft in Arcadia, FL.

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 more gas to be transported from Houston 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 (HDD) or auger drilling technology have been used, based on the respective project requirements. For the crossing under Highway 70 in Arcadia, the new Herrenknecht Direct Pipe method was used for the first time in the U.S. 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 meters (7 feet) – allowing for an accurate alignment with a horizontal and vertical curve.

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The Herrenknecht Pipe Thruster pushes the Direct Pipe machine and pipe forward with an average thrust of 28 tons.

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 feet) and 1,828 meters (6,000 feet), 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 tonnes (max. 28 tons) is transferred to the Direct Pipe machine ahead. Highway 70 was swiftly and safely under passed. 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-meter (705 feet) pipe string. The Herrenknecht machine reached the target pit on Aug. 29.