Evaluation of Failure Pressure for Gas Pipelines with Combined Defects

Abstract

The paper presents the study of the influence of mechanical damage on the safe operation of gas transmission pipelines. The main types of pipeline damage with the actual parameters and their influence on the operational parameters are analysed. The damaged fractures of the section of the pipeline Kaunas (Lithuania)-Kaliningrad (Russia) were investigated in the laboratory. The main operational characteristics and the structure of the pipeline's metal after the period of long-term operation were determined using various research and experimental methods. The influence of the pipeline's damage was modelled by using the Finite Element Method and the ANSYS code. The predictions of the failure pressure were made, taking into consideration the actual properties of the pipeline's metal. Techniques including the hardness and microhardness measurement, chemical analysis, the impact strength test, and metallography analysis with an optical microscope, were used in the experimental study.

Mechanical Behavior of High-Strength, Low-Alloy Steels

“…In this context, knowledge of the microstructural and mechanical properties of such materials, as well as the development of accurate design and inspection methodologies is of major importance. Lavigne et al [4] present a comprehensive study of the microstructural and mechanical characterization of API 5L X52 steel; Silva et al [5] discuss the effect of precipitation and grain size on the tensile strain-hardening exponent of API X80 steel; Liu et al [6] analyze the local buckling behavior and plastic deformation capacity of high-strength X80 steel pipelines subjected to strike-slip fault displacements; and Vilkys et al [7] study the influence of mechanical surface defects on the safe operation of gas pipelines on the basis of fragments collected from operating parts.…”

Mechanical Properties of Gas Main Steels after Long-Term Operation and Peculiarities of Their Fracture Surface Morphology

“…At the same time, the processes of aging and the accumulation of defects in the metal of pipes experiencing different power effects will occur in different ways. In this paper, the cutting of fragments (and, accordingly, specimens from them) was performed at a distance of less than 1/3 of the length of areas between pumping stations, which makes it possible to consider the studied specimens as the most damaged ones, since a higher level of operating pressure drops in pipelines at the outlet of pumping stations increases the average level of stress in the pipe wall [18]. The failure kinetics of the exploited steels of gas mains were investigated by the method of complete diagrams.…”

Considerations on the Evaluation and Management of Volumetric Surface Defects on Pipelines Using 3D Scanning and Finite Element Analysis

“…The most important factors affecting the integrity of pipelines are the corrosion and erosion processes that may generate local metal loss defects (Volumetric Surface Defects -VSD). As it is known [1][2][3][4][5], the residual mechanical strength and the operational safety of the steel pipelines is mainly determined by the following categories of factors: factors regarding the aggressiveness of the gases/fluids transported; factors regarding the quality of the steel from which the pipes are manufactured; factors regarding the constructive conception of the pipes and the technologies of pipe manufacture; factors regarding the working regime for gas/fluid transportation through pipelines.…”