Grading seabed pipeline construction method via ditching twice and stopping bending through preheating

Abstract

The invention relates to a grading seabed pipeline construction method via ditching twice and stopping bending through preheating. The method is characterized in that 1) a slight bending in the side direction is induced on a plurality of selected pipeline sections in a route of the seabed pipeline through preheating, the cooling resilience of the pipeline sections is restrained by ditching, thus the pulling stress is initiated in the pipeline wall to partially offset the compressive stress initiated in the pipeline wall by a heat load after the pipeline is officially put into production, and the purpose of avoiding vertical bending of the pipeline on the seabed is reached; and 2) the control of preheating bending in the side direction and restraint of bending resilience in the side direction by ditching twice are realized, the first ditching is implemented on pipeline sections beyond the occurrence plan of bending pipeline sections in the side direction, and the pipeline sections are submerged in the ditch to ensure that the bending induced by preheating in the side direction occurs in the planned position without restraint of the pipe ditch; and the second ditching is carried out during the preheating process, and the pipeline sections of which bending occurrs in the side direction are submerged in the ditch, and after preheating finishes, cooling resilience of the pipeline sections is restrained so as to initiate pulling stress.

Description

technical field [0001] The invention relates to a subsea pipeline construction method for digging trenches twice in stages, in particular to a construction method for preventing vertical buckling failure of the pipeline after service by utilizing preheated lateral buckling cooling springback to induce pre-tension stress. Background technique [0002] Due to the requirements of flow assurance, offshore oil needs to be transported in pipelines under high temperature conditions. Inevitably, the thermal load will cause significant axial force in the pipe wall, which may lead to vertical or lateral buckling of the pipeline and cause failure. invalidated. In order to avoid vertical thermal buckling of submarine pipelines on the seabed, the common engineering solution is to bury the pipeline on the seabed or pile up rocks above the pipeline to restrain the pipeline, but for long-distance submarine pipelines, similar anti-buckling measures are very expensive. High, and bring diffic...

AI Technical Summary

Problems solved by technology

In order to avoid vertical thermal buckling of submarine pipelines on the seabed, the common engineering solution is to bury the pipeline on the seabed or pile up stones above the pipeline to restrain the pipeline, but for long-distance submarine pipelines, similar anti-buckling measures are very expensive. High, and bring difficulties to later detection and maintenance

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