Sustainable pipeline construction and the upgrade of trenchless methods


The development of renewable energy and the construction of a sustainable power grid are the challenges for future energy supply. At the same time, pipeline networks must be maintained and expanded for energy security and the availability of newly developed sources such as hydrogen power. 

This includes not only the provision of sufficient transmission capacity, but also the protection of the networks against the increasing threat from environmental factors such as storms, wildfires and flooding.

Due to the increased environmental awareness of the public, smart trenchless installation methods are needed for fast and safe installation of pipelines and underground cables with minimal impact on the surroundings. Trenchless methods play a key role in urban, densely populated areas or when obstacles such as waterways or transport routes have to be crossed. 

Proven tunnelling and pipeline methods are used to install steel pipelines or casings, plastic cable ducts or tunnels. New methods and the further development of existing technologies now offer suppliers, grid operators and contractors a wide range of methods for their increasingly demanding projects. Today, trenchless technologies cover the entire geological spectrum, with high flexibility in terms of diameters, drive lengths and depths of the network sections to be installed. 

As the requirements of pipeline and underground cable construction are quite similar and encounter the same challenges, the industry needs to get prepared. Contractors must therefore equip themselves with a broad knowledge of the latest technologies to be able to cover the wide range of project conditions.

Horizontal directional drilling

For crossing obstacles along the pipeline route, horizontal directional drilling (HDD) is still the preferred option, as long as the ground conditions allow a safe drilling process. In order to increase safety and the application range in HDD, features like the downhole tooling, torque-upgrade possibilities of existing rigs and new rig concepts have been developed in recent years. A compact rig design and adapted capacities for small-diameter installations of medium length assure high efficiency and rapid implementation of the upcoming projects in pipeline and grid construction.

HDD goes greener

In order to cope with the requirements of drilling in urban areas and to make the use of green energy feasible in the long run, Herrenknecht has developed a very compact Hybrid Rig HK80CK on a crawler base. This rig is able to push or pull 80 t and has a torque of 60,000 Nm powered by a 250 kW electric engine. Several design features have been implemented to achieve a small footprint on site and high mobility for relocation of the rig.

At the same time, the compact Hybrid Rig considerably reduces noise and exhaust emissions for operation in urban areas. The unit is autonomous and runs all equipment from one electrical source. The electrical power can come either directly from the grid or from a separate generator. This generator is able to run not only the rig, but also the recycling system, transfer or mixing tanks, breakout wrenches and even the high-pressure mud pumps. All accessories are available in electrical versions, so the Hybrid Rig is, simply said, getting in line with all existing electrically driven equipment. 

An all-electric HDD Rig is on the way as a further indispensable step toward the energy transition, making green energy usable in the drilling industry. A directly electrically driven rig allows the use of green electricity and assures higher efficiency without the losses associated with the hydraulic system. Once developed and tested, the principle can be transferred to all rig sizes, creating a new generation of Electric HDD Rigs.

Small-diameter Direct Pipe

Over the past 15 years, the Direct Pipe method for trenchless installation of prefabricated steel pipelines has established itself worldwide. It combines the advantages of microtunnelling with the Pipe Thruster technology to enable trenchless installation of pipelines and casings in difficult ground conditions while reducing the risks usually associated with HDD. 

Typically, Direct Pipe is used to safely cross rivers. Thanks to further technical development and growing popularity among clients and contractors, the range of applications for Direct Pipe has steadily been expanded in recent years. Today, Direct Pipe is also increasingly used for pipeline or cable landfalls, especially where strict environmental requirements in coastal areas have to be considered. New developments in machine technology, for example the jet pump and the cutterhead design, now make it possible to use Direct Pipe even with small diameters starting at 24-inch.

E-Power Pipe for long drives in small diameters

In order to install non-pressure-resistant pipes underground with minimal overburden and high precision over long distances, the E-Power Pipe technology was developed. In a two-stage process, basically a pilot drill with an AVNS Slurry MTBM followed by pull-in of the product pipe, the E-Power Pipe system installs small-diameter pipes or bundles underground. The borehole remains mechanically supported the whole time. During insertion, if necessary, the product pipe is mechanically and thermally connected to the ground with the addition of backfill material. The current record installation length of 2000 m was achieved in early 2022 in the Netherlands, where an HDPE pipe bundle for underground cables was pulled into a 20-inch borehole. 

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