SU1129449A1 - Method of lifting underwater pipeline end from bottom - Google Patents

Description

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4 CO The invention relates to construction and can be used in the repair of subsea pipelines. There is a known method of lifting the end of the undersea pipeline from the bottom, which consists in snapping the end of the underwater pipeline, applying tension and lifting to it 1. Due to tension, the bending stresses are reduced. However, the known method is laborious, since the tension is created by a special device located on a vessel with a powerful engine or large crust. The closest to this invention is the method of lifting the end of the subsea pipeline from the bottom, consisting in snapping the end of the pipeline to the pontoon and having a polyspast kory, blowing the pontoon while simultaneously changing the length of the polyspast 2. The disadvantage of this method that does not require the use of large korya is It is not possible to create a tension in the pipeline, as a result of which the flexural strength of the pipeline may be impaired when lifting from great depths. The aim of the invention is to preserve the flexural strength of the pipeline when lifting from great depths by ensuring its tension. This goal is achieved in that according to the method of lifting the end of the subsea pipeline from the bottom, consisting in securing the end of the pipeline to the pontoon and having a polyspast kory, blowing the pontoon with simultaneous change of the length of the polyspast core, use the bottom of the bottom type and position it in the pipeline from the free end last, and the polyskast core is attached to the pontoon. At the same time, the pontoon is fixed to the end of the pipeline by means of a flexible rod. FIG. 1 and 2 are schematically shown, respectively, the initial and final phases of the rise of the end of the pipeline. The method is carried out as follows. Stuck the end of the pipeline 1 to the pontoon 2 by means of a flexible pull 3 and attach the pontoon by means of the polyspast 4 to the bottom bark 5 located in the pipeline section from the side of its free end. The end of the pipeline is lifted by blowing the pontoon 2 while simultaneously increasing the length of the chain hoist 4. Tension in t 3 and the polyspast 4 created by the lifting force of the blown pontoon ensures that the pontoon is held strictly on a vertical trajectory and, therefore, tension is created in t 3 and the pipeline itself. 1. The tensile stresses in the pipeline reduce the deflection of the end of the pipeline during lifting, and thosem reduce the bending stresses by the most. The pontoon is purged from the auxiliary vessel 6. Thus, due to the use of a corona type, the tension of the end of the pipeline is observed, which preserves the flexural strength of the pipeline when its end is lifted from great depths.

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FIG. 2

Claims (2)

(5.7) 1. METHOD OF LIFTING THE END OF THE UNDERWATER PIPELINE WITH BOTTOM, consisting in dangling the end of the pipeline to the pontoon and having a chain hoist anchor, blowing the pontoon while changing the length of the chain hoist of the anchor, characterized in that, in order to maintain the bending strength of the pipeline when lifting from great depths by ensuring its tension, use the bottom type anchor and position it is in the alignment of the pipeline from the side of the free end of the latter, and the chain hoist anchors are attached to the pontoon. 2. The method according to π. 1, characterized in that the pontoon at the end of the pipeline is sprinkled by means of a flexible rod.