Non-lifting laying of the pipelines
NON-LIFTING LAYING OF THE PIPELINES (EN: non-lift pipe laying; DE: Absenken einer Leitung durch Rohrgrabenaushub unter vormontiertem Strang; FR: pose des conduites sans montee prealable; ES: colocacion de tuberias sin elevacion, prealable; RU: бесподъемная укладка трубопроводов) is the laying of the pipes without the preliminary lifting and thrusting of them onto the trench.
The non-lifting laying of the pipelines comprises the assembly and laying of the continuous thread of the pipeline onto the ground along the designed axis of the route, the heading of the trench immediately under the pipeline, the steady independent lowering of the pipeline into the trench under the impact of the force of gravity. During the non-lifting laying of the pipelines, they use the excavator for the deepening of the pipes, which is equipped with the inclined working implements, which are mirror-symmetrically positioned one in relation to another, and which are developing and extracting the soil from under the pipeline at the both sides. They usually use the excavator with the working implements of the bucket-wheel type. In those cases, when the work of the bucket-wheel excavator for the deepening of the pipes is impossible or difficult (at the sticky soils, very rough terrain, which is requiring the heading of the trenches with variable depth, and so on), they replace it with two single-bucket excavators, which are equipped with the tilting booms, which are situated at the opposite sides of the pipeline.
The non-lifting laying of the pipelines may be used both for the laying of the pipeline using the pipes with the factory (or base) insulation, and for the laying of the non-insulated pipes. In the latter case, they perform the cleaning and insulating works either prior to the passage of the excavator for the deepening of the pipes, or after this excavator by the combined cleaning-insulating machine with the usage of the polymeric tapes. Such machine belongs to the structure of the unified technological complex (with the excavator for the deepening of the pipes), and moves right behind this excavator, using the hanging of the pipeline within the upper space of the trench. The non-lifting laying of the pipelines decreases the total quantity of the machines and the quantity of the serving personnel, improves the conditions of the labour, improves the quality of the laying works. There also increases the reliability of the laying of the pipeline, because with this method there decrease the loads onto the pipeline during the process of its laying, are created better conditions for the monitoring of the quality of insulation, and are provided the conditions for the instant correction of the defects, which have been found.
There also assists to the improvement of the reliability the laying of the pipeline onto the fresh bottom of the trench, and the instant covering of this pipeline with the non-compacted loosened soil. During the non-lifting laying of the pipelines, there is excluded the touching of the lateral surface of the pipeline with the walls of the trench during the laying of the pipes within the curved sections of the trench.
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