OIL AND GAS TRANSPORTATION AND STORAGE Influence of installation elastic bending on stress-strain state of pipeline aboveground passages in mountains

S Yanovskyi
Cand. Sc. in Engineering. Branch "Oil-Trunk Pipelines "Druzhba" of PJSC "Ukrtransnafta" The experiment-calculated methods of diagnosing stress-strain state of the pipeline aboveground beam passages are shown. By the example of pipeline aboveground passage in the Carpathians the influence of installation elastic bending on its stress-strain state was studied. Aboveground passages because of various natural and artificial obstacles (rivers, ravines, irrigation channels etc.), as well as dug-up
more » ... s well as dug-up sections of underground pipelines for performance of repair works, belong to especially responsible sections of main oil and gas pipelines. Every such section consists of straight and curved elements (pipes). In many cases on passages through obstacles of relatively small width they use beam passages without compensation of longitudinal strains and without special bearings on the edges. A characteristic feature of such passages is their hypersensitivity to daily and seasonal air temperature fluctuations, to changes in the pipeline operating mode, to subsidence of bearings and seismic motion effects on adjacent underground sections. The stress-strain state (SSS) is one of the main parameters determining strength, tenacity and operation reliability of both open sections and the whole linear pipeline portion. The strain state must be determined and analyzed both at the pipeline design and construction phases and during pipeline operation. It should be noted that determination of the pipe material SSS is an important element of diagnosing of the general technical condition of main pipelines [1], forecasting of strength and endurance of their linear portion [2], taking of a decision on the possibility to continue safe operation or the necessity to perform maintenance and repair works and constructive implementation thereof The necessity to determine strains in the pipeline wall at the operational phase arises mostly on the so called "potentially dangerous sections" which are operated in difficult conditions and are affected by significant loads related to change in their estimated spatial arrangement.