Herrenknecht helps to complete pipeline project

Being used for decades, HDD methods have proved their worth for many boreholes. However, HDD reaches technical and economic limits in heterogeneous, unstable grounds.

During fall 2016, PPI Chrobok S.A. installed two new gas pipelines in Poland, which run along existing gas lines and through geologically challenging terrain. To lay the 700 m and 464 m pipelines, Herrenknecht's Direct Pipe technology was used in Poland for the first time.

The sandy, sticky clay of the pipeline crossings in Wierzchowice and Czeszów presented the drilling crew on the job with such unstable project conditions. Additionally, with the two alignments running along existing gas pipelines, this proved to be a challenge.

Uncontrolled deviations during the drilling process had to be avoided at all costs. In view of the above considerations and requirements, the main contractor, PGNiG Technologies S.A., together with drilling contractor PPI Chrobok S.A. opted to use Direct Pipe technology from Herrenknecht. This method combines the advantages of microtunnelling and HDD technology. In a single step, the required borehole can be created and the prefabricated pipe is simultaneously installed without a trench.

The gyrocompass navigation system allows for exact steering of the TBM. Therefore, the drilling crew precisely installed the two pipelines, safely crossing beneath an ecologically sensitive fish pond.

The sticky ground , which can cause blockages, was not a barrier for the Direct Pipe method. Even at very high levels of friction resistance, the 500 t of thrust provided by the Pipe Thruster in the launch shaft is more than enough. Despite the small overcut of only few centimeters, no damages were detected at the coating after the pipe laying.

Overall, a very positive conclusion was drawn after successfully completing the project. With daily best performances of 147 m, Roland Koska, Planning and Monitoring Manager for GAZ-SYSTEM, summarises: "As a combination of HDD and microtunnelling, Direct Pipe overcomes their respective limitations which, to a large extent, are no longer obstacles to pipeline construction. This will also allow us to pursue new projects in the future and complete them economically, quickly and with minimal impact on the local infrastructure and environment."

Read the article online at: https://www.worldpipelines.com/product-news/23012017/herrenknecht-helps-to-complete-pipeline-project/