Research on Effect Factors of Mechanical Response of Cross-Fault Buried Gas Pipeline Based on Fluid-Structure Interaction

Long-distance buried pipelines inescapably go through seismic fracture zones which makes the buried pipelines be easily influenced by the diastrophism. Most of the existing studies only focus on the two-phase contact between pipeline and soil, and the mechanical behavior of the cross-fault pipeline under transportation condition has not been studied. In this paper, ADINA finite element software was used to establish a pipe-soil-fluid three-phase coupling model based on fluid-structure interaction (FSI), and the effect factors of mechanical response of cross-fault buried gas pipeline were studied. Results indicate the following conclusions: (1) The model considering the effect of fluid-structure interaction can effectively simulate the mechanical response of pipelines in the actual working condition. (2) It is safer for the pipeline to pass through the strike-slip fault, and the most dangerous to pass through the reversed fault. (3) When the fault displacement is less than 1.3m, the optimal angle range to pass through the strike-slip fault is 30° to 60°, otherwise the optimal angle range is 30° to 45°; the optimal angle range to pass through the normal fault is 30° to 60°; the optimal angle to pass through the reversed fault is 90°. (4) When passing through the reversed fault, the optimal buried depth of pipeline is 1m-1.5m. (5) When the fault displacement is less than 1.3m, a certain delivery pressure (8MPa) can enhance the ability of pipeline to resist the strike-slip fault dislocation.

Measured Pipe Stresses on Gas Pipelines in Landslide Areas

Landslides are a risk to buried gas pipeline infrastructure, but these risks are particularly difficult to assess given the complex nature of landslide movements. This paper presents of portion of research conducted at the University of Manitoba where gas pipelines within active landslide areas were monitored over a four-year period. Two locations were examined in Western Manitoba within the Assiniboine river valley where a shallow natural gas pipeline runs parallel to the valley slope. A field investigation and monitoring program was undertaken where surficial ground movements and soil and pipe temperatures and pipe strains through strain gauges were measured. Monitoring results identified soil near the pipeline does not freeze, and ground movements are <50 mm/year. The monitoring results also showed pipe stresses and behaviour were affected by backfilling, thermal changes, soil-pipe relaxation, and ground movements. An unexpected outcome of the research was the response of the pipeline to slight ground movements was easily captured by the strain gauges and these movements, slow or surges tended to occur at the same time between the two sites suggesting movements occur due to regional environmental affects.

Numerical Evaluation on Improvement Performance of Waved Connection to Reduce Damage on Buried Gas Pipeline

One of the major challenges for the oil and gas industry is to keep buried metal pipes safe from faulting. This paper discusses about a solution to keep buried pipes safe. In this study, after examining the different dimensions of the effect of wave connection on improving the performance of buried metal pipes, by changing the geometric shape of the wave connection such as doubling it, the behavior of the pipe is greatly improved. Waved connections, by their local deformation, create a rotational joint in a limited area so that other parts of the pipe remain intact. In this paper, the behavior of buried pipes due to slip direction fault displacement by modelling with Abacus software version 2017 and selection of 4-node shell element and 8-node shell element have been used for pipe and soil modelling, respectively. In this paper, by comparing to a single waved connection with a double waved connection, the performance of the pipe due to the faulting phenomenon was evaluated. The results show the improvement of the excellent performance of the double joint by reducing the plastic strain values. In addition to increasing the ductility of the pipe, the double connection has been able to reduce the strain values by about 50% compared to the single connection. In general, this paper shows that the use of wave connections can significantly increase the level of safety of buried gas pipelines without increasing the cost.

Application of Transient Electromagnetic Method in Municipal Buried Gas Pipeline Detection

The safe operation of gas pipeline is related to the liveihood of people, in the process of operation, many factors will cause pipeline failure, leakage and accidents and thus impair people’s well-being and property safety. This paper puts forward the transient electromagnetic method for in-service detection of municipal buried gas pipeline, mainly introduces the principle of transient electromagnetic method and the factor analysis of pipeline failure, and comprehensively analyzes the problems existing in the application of transient electromagnetic method in in-service detection of municipal buried gas pipeline combined with two examples of gas pipeline detection. The result shows that transient electromagnetic method is practical in the detection of municipal buried gas pipeline, which can better distinguish corrosion thinning and interference, and provide reliable theoretical data basis for in-service safe operation detection and maintenance of municipal buried gas pipeline.