Papers by Keyword: Gas Pipeline

Abstract: Modern pipeline steel has high toughness and ductility, which can effectively prevent long-distance crack propagation. The full-scale blasting test is the most effective method to verify and evaluate the crack propagation and arrest behavior in high-grade pipeline steel pipes. This article investigates the crack propagation and crack arrest behavior of X90 grade natural gas pipeline steel pipes through full-scale blasting tests. The test results show that once the X90 grade natural gas pipeline steel pipe cracks and propagation under a pressure of 12MPa, as long as the Charpy impact toughness CVN of the steel pipe is greater than 286J, it can ensure effective crack arrest of the pipeline, providing technical support for the application of X90 high-grade pipeline steel pipe in high-pressure transmission pipelines.

Abstract: This paper presents a case study of an in-service failure occurred in a pressurized gas supply pipeline, which has been recurring in recent years, particularly during the winter season. The investigation focused on two pipe coupons extracted from a DN 300 pipeline, which had sustained damage while in operation as part of a natural gas pipeline. Through the implementation of mechanical and non-destructive testing methods on the pipe couplings and their welds, multiple non-conformities were identified. These non-conformities were found to be the root causes of failures that occurred after welding and during operation. The findings of this investigation have led to several valuable comments and recommendations, which are beneficial for manufacturing companies and clients alike. Implementing these suggestions can contribute to enhanced safety and operational efficiency in gas pipeline systems.

Abstract: At present, when connecting polyethylene pipes for gas pipelines, two basic methods of welding are used: hot tool butt welding and welding with couplings and embedded heater. Hot tool flare welding is mainly used in polymer water supply systems. This paper presents results of research on implementation of this welding method when connecting polyethylene pipes in gas supply systems. It is proposed to use pieces of polyethylene pipes of larger diameter as couplings. Preliminary prolonged tensile tests of obtained welded joints showed effectiveness of this technology when joining polyethylene pipes.

Abstract: Corrosion has been the most common type of defects on oil and gas pipelines. For in-service pipelines the corrosion defects are detected through the in-line inspection and evaluated by integrity assessment methods such as ASME B31G. However, the safety factors of these methods have not been carefully studied. In this paper, the Monte Carlo simulation is carried out to estimate the reliability of the corrosion defects of critical sizes with different safety factors. The results show that the reliabilities of the critical defects increase with the increase of the safety factor, but decrease with the increase of the defect length even under the same safety factor. The commonly used safety factor 1.39 can ensure the target reliability is met in the specified case in this paper. But for high consequence cases the selection of safety factor needs further research.

Abstract: The paper reviews current situation of high design factor application abroad, and analyzes development of high-strength pipeline in China. It shows that related technology has greatly improved in China, such as manufacture of high strength pipe, inspection, quality control, pipeline construction and pipeline integrity management. So it is available to use 0.8 design factor for the class one location in China. And the paper also introduces trial section experiences in the third West-East pipeline on safety pre-assessment, design check, pipe specification, construction technology and integrity management plan. With relative specifications further perfected, it is promising to put the 0.8 design factor into a wide use in Chinese pipeline project.

Abstract: Pipeline transportation is the most economical and reasonable way to transport natural gas. However, there are still some technical problems in high grade gas pipeline, in which fracture control is one of the key problems. The ductile fracture for long-range expansion is the most destructive failure mode of high pressure gas pipeline. In this study, the determination and prediction methods of crack arrest toughness of high grade (X80 and above) pipe line steels were introduced. Their application range, advantages and disadvantages were analyzed. The results showed that the toughness of X80 pipe line steel can meet the needs of the pipeline crack arrest requirements. It is difficult for the ultra-high-grade (X90 and above) pipe line steel to arrest crack by their own toughness. Therefore, the crack arrester should be installed. This paper introduced the crack arrest principle, advantages and disadvantages of various kinds of crack arresters.

Abstract: Based on the data of X-ray texture and structure analysis of the material of main gas pipelines it was shown that the layerwise inhomogeneity of tubes is formed during their manufacturing. The layerwise texture inhomogeneity of steel tubes, obtained by hot rolling at the air, differs depending on variation of technological parameters of their processing in inner and outer layers, i.e. the temperature and deformation gradients, penetration of interstitial impurities into the surface layer from surrounding atmosphere etc. The thickness of the surface layer with modified texture parameters depends on the temperature of rolling and its regime. Under exploitation when stress-corrosion cracks grows and reach the layer with a modified texture, their opening is slowing down or stops because of the high mutual misorientation of grains of different layers and the necessity of changing the plane of moving cracks, what requires additional tensile stresses. Layered textures of different gas tubes were compared. It was shown that character and degree of arising inhomogeneity correlates with the tubes resistance to stress-corrosion cracking.

Abstract: The girth weld defect is one of the most common types of defects on oil and gas pipelines, which can have a strong impact on the operation safety. Several girth weld failure accidents have occurred on PetroChina’s pipelines in recent years. In this paper, PetroChina’s current work on inspection and fitness for purpose assessment of girth weld defects is summarized. The in-line inspection has been proved to be the best practice for oil and gas pipeline defect inspection, but there are still some technical issues such as defect characterization and parameter selection. Fitness for purpose assessment methods for girth weld defects include strength assessment method based on plastic collapse, FAD method based on both plastic collapse and fracture, simplified factor method and numerical analysis method based on finite element. It is critical to identify the actual type of defects detected in in-line inspection to select an appropriate assessment method. The identification of various loads and the selection of appropriate material parameters are also important issues in assessment procedure. The key techniques to be developed include defect characterization, load identification, assessment of defects on high grade steel pipes, reliability-based assessment, etc.

Abstract: This paper proposes a leak detection method using acoustic. The Hamming chirp signal injected into the pipeline system and the estimation of the leak location from the delay time passing by the reflection in the pipeline if there is a leak. By using Hilbert-Huang Transform (HHT), it can give a useful signal to verify the leak. HHT transforms Empirical Mode Decomposition (EMD) and Hilbert Spectrum analysis to perform time-frequency analysis. The leak location can be detected by multiplying by the speed of sound. This simple method gives accurate leak location and easy to implement.

Abstract: Energy efficient problem of wireless sensor networks for oil and gas pipeline systems is a fundamental problem, and furthermore, data prediction algorithm can effectively reduce the communication energy consumption of WSNs. This paper firstly analyzes existing common data prediction algorithms and the data characteristics of oil and gas pipelines monitoring data. And then introduces the three-layer architecture of WSNs. Lastly, the adaptability analysis of various prediction algorithms are proposed, the analysis result shows that the accuracy of data prediction algorithm can meet requirements of oil and gas monitoring, and prediction algorithms can effectively reduce the amount of data transmission and prolong network life span.