We consider the problem of designing a new natural gas transmission network and expanding an existing network while minimizing the total investment and operating costs. We develop a mixed-integer nonlinear optimization model to determine pipelines in the network, compressor stations with their capacity as a variable, and their instalation schedule in a multi-period planning horizon. The model further decides on the amount of the produced natural gas in the steady-state flow for each period in the network. The model is solvable using Baron solver in Gams. We conduct computational studies on various cases generated using realistic network structure and data based on the natural gas network in Iran. Our analysis provides insights into sensitivity of network configuration and operations within different periods in the planning horizon and cost parameters of natural gas networks. Result proved 30 percentage decrease in cost of gas network transmission.

In this paper we compare the economic costs and benefits of providing the need of Tehran for electricity through two alternatives, namely transmission of gas or electricity from point of production to Tehran. The basic facts that affect the study are that there is a need to establish a power station to generate the needed electricity for Tehran as the main centre of consumption and that the main centre of gas production is located in Asalooyeh. The basic question to which this study responds is that establishing such power plant in which area between the gas production and electricity consumption centers results in lower costs. In other words, which choice between transmitting electricity and gas is most advantageous for the country.In this paper, different options of gas and electricity transmission between the closest area to the gas production center in Asalooyeh and the closest area to the electricity consumption center in Tehran are studied. Production capacity of the hypothetical power plant is taken as 1000 megawatt with maximum 1200-kilometre distance between the point of production of natural gas and Tehran.The existing electricity and gas networks of the country have been ignored and it is assumed that there is no spare capacity in either electricity or gas transmission lines. The study reviews different options, namely electricity transmission through mono-circuit and bicircuit 230 and 400 kilovolt transmission lines and gas transmission through 28, 30, 48 and 56-inch pipe lines and takes into account loss of electricity due to transmission. The best option to minimize the costs of providing the consumers with electricity in terms of the national economy is the establishment of the power plant close to the gas production center and transmission of electricity to the consumption area.

Pipeline is one of the main methods of natural gas transmission. This method has some limitations such as inflexibility, limited gas transmission capacity, and high costs of installing and maintaining the equipment. To overcome some of these limitations, dense phase gas transmission (supercritical fluid) has recently been proposed. Among the benefits of supercritical natural gas transmission, increased density, decreased viscosity, less compressor stations, smaller pipe diameter, reduced pressure drop, lower maintenance costs, as well as the lack of two-phase fluid formation should be mentioned. To change the gas from usual condition to a dense phase, the gas pressure should be more than the cricondenbar point and the gas temperature should be between the critical temperature and the cricondentherm point in the phase diagram. In this paper, after expressing the theory and equations of gas transfer, the results of two case studies on natural gas transmission in supercritical conditions are presented. These studies showed that the compression and cooling energy in the supercritical gas transmission were 70% and 50% lower than the two-phase gas transmission mode, respectively. The extractable amount of liquefied gas in the supercritical condition was 74% higher than the two-phase state. Also, the amount of energy of the compressors in the dense phase state was 51% and 63% lower than the medium and low-pressure gas transmissions states, respectively.

The study aimed to evaluate the behavior of typical natural gas transmission pipelines in landslides and investigate the effect of various parameters such as internal pressure, pipe diameter, and soil type on their active lengths. Nonlinear Finite Element Analyses (FEA) were performed using the Winkler-type beam-on-spring model to evaluate the pipeline response in landslides. The FEA results showed that the stress and strain distribution along the pipeline were primarily positive, which indicated that the ground movement was resisted by axial tension force (membrane action) of the pipeline. The maximum axial strain occurred at the beginning and the end of the landslide zone, indicating that the pipeline would fail at these locations. The FEA results also indicated that the maximum axial forces in all cases were very close to the section capacity of the pipe, indicating that landslide-induced ground displacements resulted in very high axial force and relatively low bending moment in typical natural gas transmission pipelines.The PRCI guidelines provide an equation for estimating the anchor length of buried steel pipelines, but the results of this study indicate that the anchor lengths are much larger than those calculated by the PRCI equation. A proposed equation based on ultimate strength of the pipe section is suggested for calculating anchor length, which gives a good estimate of the anchor length with an average error of 4% relative to the analytical results. Overall, the study concluded that the internal pressure of the pipeline had no significant effect on the anchor lengths of the pipelines, and the proposed equation provides a more accurate estimate of the anchor length of typical natural gas transmission pipelines.

The Sistan sedimentary plain has been the habitat of various human communities in the past due to its favorable environmental conditions. Therefore, there are many ancient hills and historical monuments in this area. Although this area is one of the important and rich ancient areas in Eastern Iran, there are still many issues and uncertainties about the history of this area, and each of the existing works can answer many of these questions. Therefore, protecting such works against natural and human destructive factors is inevitable. The archaeological survey of the Zahedan-Zabol gas transmission route was carried out to identify the ancient sites on this route and protect them against any damage and destruction. Along the route designed to install the gas pipe, there are many ancient sites and important historical centers such as Shileh, Ramroud, Roud-Biaban, and Shahr-i Sokhta. This survey was conducted with an intensive and step-by-step method to identify and investigate all the sites of this important cultural area and thereby protect them from possible future dangers. In sum, 38 ancient sites and mounds were identified, and surface movable and immovable works, belonging to prehistoric, historical, and Islamic eras, were collected and documented. These cultural materials included 322 pieces of pottery and 157 index objects, all of which were categorized and studied. In this article, the authors try to provide a brief report of this study along with a description of the findings and results.

Nowadays, designing the resilient natural gas transmission network is an important and essential issue for industry experts and policymakers due to great economic, health, security and social losses created by relevant disruptions. This paperdevelops a two-stage approach for the design of resilient natural gas (NG)transmission network. In the first stage, the risk of each pipeline route is calculatedbased on distances of diffusion concentration. In the second stage, a multi-objective mixed possibilistic-stochastic programming model is presented to enhance theresiliency of the natural gas network by utilizing proactive strategies such as parallel pipeline, fortification and back-up turbo compressor under demanduncertainty and disruption risks. In addition, the proposed model considers different failure modes of the pipeline. Finally, the model validation is done by the data of areal case study. Our analysis shows that the performance of the natural gastransmission network is highly vulnerable to demand fluctuations. Also, resultsindicate that employing both pipeline fortification and back-up pipeline strategieshave numerous impacts on the resiliency of the NG network. Important managerial insights are obtained from the model implementation in a case study.

The purpose of this study is to investigate the pigging operation, why it is done, the types of pigments available, and its importance in the gas industry. It is important to identify clogs and reopen them, as well as to identify cracks and corrosion in valves and pipes. The main advantages of piglets include the low-cost cleaning of pipelines, the possibility of rapid sampling inside the pipes to detect and test for impurities, the possibility of inspecting pipelines without the need for power outages, and the ability to use PLCs. In water and sewage pipelines, oil and gas, and petrochemical pipelines have a basic application for cleaning and inspection of pipelines. This study reviews the generalities of pig, pipeline operations, and new aspects of recent technologies in this field, including necessity, capacities, challenges, and innovations of pipeline technology in the maintenance and operation of oil and gas pipelines and the other hydrocarbon products, introducing the types of used pigs, factors for selecting the appropriate pig in terms of application, cleaning, inspection and monitoring of pipelines, comparison and applications of smart pigs, and how they work and record problems in pipelines, decontamination. The results of this study indicated that one of the important strategies in the field of reforming and performing the follow-up process can be increased the statistical research in order to develop practical regulations related to the maintenance of pipelines along with the responsibility of production and transmission..