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Extract from the RuhrgasForum magazine, January 1996
Apart from the open-trench construction, pipe installation also makes use of other pipe-laying methods, like drilling, pushing or ramming with impact power. These trenchless methods are applied, when it is essential to avoid traffic disruption, for constructional or economical reasons or whenever environmental protection is required.
Under certain circumstances, if pipeline constructions on a larger scale require under road, railway or river crossings, the pipe laying method using a horizontal ram may be superior to the conventional drilling-pushing methods. The technical guidelines, however, still show restrictions for an extensive application of this pipe installation system. Only recently, details about the effects of the impact energy on the steel pipe material structure, as well as calculation documentation for the economic layout of the installation pipes were not available. To confirm the suitability of the ramming method, the Ruhrgas AG has now carried out measurements with three jacket pipe installations (Ruhrgas-Leitungen Bonn-Euskirchen, Herne Horsthausen and TENP Loopleitung Schwarzach Rheinbischofsheim) and one product pipe installation (NETRA-Abschnitt Wardenburg Achim). By making expansion and acceleration measurements of the installation pipes, the amount of strain caused by the impact power was determined. These accompanying measurements at the jobsites were jointly carried out by an expert examiner (Prof. Dr.-Ing. Stein & Partner, Bochum) and a manufacturer of horizontal rams (TRACTO-TECHNIK, Lennestadt). The result: it is unnecessary to add further design loads or precaution correction values to the calculation of the installation pipes.
As the evaluation of these results proves, the installation pipe is not damaged by the ramming method. We come to the following conclusion: under consideration of certain constructional measures, this method is highly recommended for pipe installation on a large scale.
Only a re-usable impact pipe, approx. 1.5 m long, which is placed between the installation pipe and the horizontal ram, is required for protecting the gas pipe. Furthermore, attention must be paid to other cables, pipes and buildings in the surrounding area, to make sure they cannot be damaged by ground
Bahn AG (German Railway):
The ramming method shows special advantages for crossings beneath railway facilities and lines.
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