10.24411/2076-6785-2019-10019
The paper presents the results of calculating the stresses in the wall of an underground pipeline loaded with single weight in the angles of rotation on convex sections of the pipeline. Taking into account the random nature of the yield strength of tube steels, samples of actual values obtained for the material of pipes from different manufacturers, the strength of curvilinear sections of the main pipeline was evaluated. The necessity of individual selection of the weight of a single weight for each section of the pipeline is justified taking into account the specific law and the dispersion limits of the yield strength of the pipe material used during the construction phase of the section.
Materials and methods
Calculation of stresses in the pipeline and verification of the fulfillment of the strength condition of the loaded curvilinear section of main pipeline was carried out on the basis of construction norms and rules (SNiP 2.05.06- 85 * Trunk pipelines). Evaluation of the strength of curvilinear sections of main pipelines in the probabilistic aspect is performed on the basis of processing random variables using methods of probability theory and nonparametric statistics.
Results
The individual laws of distribution and the limits of dispersion of the yield strength of a material of even pipes of the same type, produced by various manufacturers, cause significant differences in the results of the evaluation of the strength of temperature-deformable curved sections of main pipelines. This fact requires the improvement of existing and the development of new methods of strength analysis, allowing to take into account the specific nature of the random nature of the mechanical characteristics of the pipe material.
Conclusions
1. The considered approach to estimating the strength of main pipelines allows to calculate the stresses of the loaded sections of underground pipelines and justify the choice of the weight of a single weight, taking into account the random nature of the yield strength σТ of the pipe material used for the construction of the curved section under consideration. 2. Due to the random nature of the yield strength σТ, the weight of pipeline weights that meet the strength condition of the curved sections of the main pipeline must be selected taking into account the dispersion limits that are individual for each type of tubular product and the laws of the distribution of σ values. 3. The accumulated information on the mechanical characteristics of the pipe material and the limits of their changes at the stages of production and operation for each linear section allows us to specify the weight or change the layout of weights at the stage of reconstruction or repair of the linear part on the basis of the considered approach.
