Direct Pipe is the most revolutionary trenchless technology

Today the Direct Pipe technology by the German company Herrenknecht has advanced far beyond traditional trenchless pipe-laying methods.

The Direct Pipe method, that had been developed in 2007, makes it possible to lay pipelines under natural and artificial obstacles with a pipe diameter of up to 1420 mm for distances of up to 2000 m saving large time and economic costs.

Direct Pipe has proven its reliability and efficiency in projects both in Europe (including construction of the Main pipeline over the Danube River in Serbia by BELTRUBOPROVODSTROY JSC), and in Russia.

The technology is based on the fact that a pipeline bore is formed in one stage by drilling the Herrenknecht tunnel boring shield AVN-800,-1000 or -1200  (depending on the pipe diameter), and simultaneously extracting the cuttings out by pumps through special haulage systems installed inside the shield. The formation of the pipe well and the punching of the pipeline are synchronised. The  control is holding by the operator, who is located on the surface in the control centre of the rig.

The borehole is formed using water and bentonite solution that erodes the rocks, extracts them and fills the formed annular space with the bentonite solution.

Once drilling is complete, the tunnel boring shield exits at the end point of the closed crossing at the pre-defined elevation. The specialists then make a detachment between the shield and the pipeline and remove the transport lines from them.

We must say that the technology allows for the possibility of reverse extraction of the installation. However, this will only be allowed if there is enough space to remove the pipe without prior decoupling. Generally speaking, the Direct Pipe method is often chosen when constructing pipelines in confined spaces – in these circumstances the Direct Pipe method can be operated in short sections, gradually joining pipe sections by welding right through the drill and push-through process.

The Direct Pipe technology does not, however, limit the choice of insulation type to the customer – epoxy, concrete, polypropylene, polyethylene or fibreglass. The rest of the parameters of the insulation coating may also be determined by the needs of the project, and not by the selected construction method.

For our customers we always identify such  benefits of using Herrenknecht’s Direct Pipe technology in the construction of closed gas and oil pipeline crossings:

  • Pipeline installation into an enclosed crossing in a single step.
  • Minimum geological risks – cutting equipment is suited to the specific soil type and can be replaced immediately during the drilling process.
  • Possibility to divide the pipe into several smaller sections.
  • Minimal environmental risks.
  • Small borehole diameter, and consequently savings due to small volume of developed soil and volume of required bentonite.
  • Single-sided requirement in site arrangement, which is particularly suitable for construction in marine and riverine approaches – no need for a construction site on the outlet side of the culvert.
  • High speed of response and jewellery accuracy of equipment operations even in the most difficult geological conditions.
  • Full control of the entire drilling and culvert installation process.

*the photos are for illustrative purposes only

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