BELTRUBOPROVODSTROY was one of the first construction companies in the post-Soviet area which has applied the advanced technology of Direct Pipe of German manufacturer Herrenknecht for implementation of closed pipeline crossings under natural and artificial obstacles.

The principle of trenchless technology of Direct Pipe consists of the installation of pipeline in one stage by simultaneous processes of borehole formation and pipe pushing into the formed borehole.

It should be noted that the two main components of the Direct Pipe equipment are the AVN tunnelling machine, used in microtunnelling, and the pipe reamer, used in DD (Directional Drilling). The worldwide experience in using these machines guarantees the efficiency and reliability of the Direct Pipe technology and the possibility to perform customised solutions for each customer’s requirements.

Direct Pipe: history

The first presentation of the Herrenknecht reamer was held at an industrial exhibition in Hanover in 2006. Already in 2007 the first tests of the equipment took place in a pilot drilling project under the Rhine River.

Since 2009, the equipment has begun its history of application in successfully implemented projects around the world: in 2009 Direct Pipe was used at first time in the Netherlands, 2010 in the USA, 2011 in Italy, 2012 in Asia, 2013 in Canada, 2016 in China and Poland, etc. In 2018, a World Record of the length of a crossing was set using the Direct Pipe method: in Auckland, New Zealand, a 48″ diameter pipe exited to the sea to divert wastewater from a treatment plant. The crossing was 1,930 metres long. Its route lay through difficult geological conditions – clay, claystone, sandstone.

In 2019, BELTRUBOPROVODSTROY constructed Europe’s longest underwater crossing using the Direct Pipe Technology. Within the project of the Turkish Stream gas pipeline construction, an underwater crossing under the Danube River had been performed by BELTRUBOPROVODSTROY team on part of the Balkan section. Its length was 1,402 metres. It was the third longest in the world (first by New Zealand and second by the USA) and the first in Europe. To find out the Customers feedback about that and other projects, please visit our special page with customers reviews.

Currently, now there are more than 150 successfully implemented Direct Pipe projects all over the world. Of those, 30% have been in geology, while the remaining 30% have been major projects in the oil, gas and mining sectors:

– 30% of the projects have been in geology containing predominantly sand, clay, stone and gravel.

– 10% of the projects were in geology containing wood.

– 10% of the projects were in geology with significant boulder and rock content.

Where is Direct Pipe used

Based on the wide range of geological conditions where it may be applied, the scope of the Direct Pipe Method for the construction of enclosed crossings includes:

• Underwater river and canal crossings,
• Exits to the sea,
• Hill, rock and mountain crossings
• Crossings under archaeological and protected areas, national parks and nature reserves
• Road and railroad crossings in challenging geological conditions where the application of Directional Drilling technique is restricted due to excavation distance, pipeline diameter or where the application of microtunnelling technique is limited by construction time, complex logistics conditions of iron-concrete pipe supply, cost considerations.

Description of the Direct Pipe technology

1. The borehole of the future pipeline is formed by drilling with AVN-800,-1000,-1200 tunnel boring equipment. The excavated rock is removed by pumps through conveying lines placed inside the shield and the pipeline. The pipeline is laid with the help of hydraulic pipe jacks HK350PT, 500PT, 750PT. Drilling and pipe ramming are synchronised with each other and are going as a simultaneous process.

2. Rocks are drilled with cutter heads, depending on the geological structure and soil category (sand, clay, limestone, gravel, rock). Water and bentonite based drilling mud are used to erode and remove the rock. These are fed into the borehole face through supply lines placed inside the shield and the pipeline.

3. The annular space in the borehole is filled with bentonite solution, which provides lubrication and reduces friction during penetration.

In case of wear of the cutting tools it is possible to replace the cutting tools by pulling out the shield and pipeline using a back puller and the subsequent installation of the pipeline following the same trajectory. Back pulling out is possible if there is a distance to accommodate the pipe bundle to be pulled out without undoing it.

In cramped conditions, where there is limited accommodation distance for the pipe string, it is possible to work with short sections of pipeline, welding the short sections together during boring and punching.

4. At the end of the sinking, the shield will reach a predetermined mark (ground surface, excavation). At this point, the shield and the pipeline are separated, the supply and transport lines are removed from the pipeline, and the tracks are dismantled for the workers to use when repairs are necessary.

It is important to note that this technology allows safe work with all types of insulation (polyethylene, polypropylene, fibreglass, epoxy coating, concrete coating); the thickness of the insulation coating is determined by the project.

The advantages of using Direct Pipe

• One step installation   
• Economic benefits
• No welding required
• Smaller bore size (compared to HDD)
• Less excavated material and less bentonite
• No risks of surface subsidence
• Single point location of equipment
• Ideal for drainage works (outlets into sea, river)
• Reduced risk due to geology: impeller matched to the geological conditions
• Continuous support of the borehole (compared with HDD)
• Safety of the environment
• Pipeline can be removed from the borehole to remedy potential malfunctions

The worldwide recognition of Direct Pipe technology already has proved it to be most efficient and economy solution for even the most complicated projects. The BELTRUBOPROVODSTROY staff has a huge experience in implementing projects using Direct Pipe Technology and widely applies it while solving the Customers tasks and requests.

*the photos are for illustrative purposes only