Influence of old rectangular repair patches on the burst pressure of a gas pipeline

Seven full scale hydrostatic burst tests were carried out on pipes extracted from an API 5LX52 gas pipeline that contained rectangular and elliptical fillet welded patches and other repairs of different geometries. All breaks took place after widespread yielding. This analysis shows that the patches that generate greater risks are those that: (1) were attached to the pipeline at very low pressure, (2) were placed to repair large defects, (3) are rectangular, long in the direction of the pipe, and narrow, (4) the quality of the weld is doubtful. Based on data reported by In Line Inspection (ILI), of the four conditions mentioned above, only the third can be assessed in order to quantify risks and to schedule replacements.     

Procedures for the strain based assessment of pipeline dents

A criterion for strain-based assessment of dents in gas pipelines has been recently proposed in the ASME B31.8 code. This work initially presents a critical review of the equations for estimating strains presented in Appendix R of that code. Next, a procedure based on B-spline curves is presented that interpolates dent geometry from data measured by in-line inspection (ILI) tools and evaluates strain components. The paper proceeds with studies to assess the influence of the ILI tool resolution and positioning on the estimation of the circumferential bending strain. Finally, the evaluation of longitudinal membrane strains is assessed by taking two alternative definitions for dent length that enters in the formula proposed in Appendix R of the aforementioned code, and comparing with results provided by Finite Element analyses. The comparison suggests that directions on how to measure the dent length might be incorporated in a revision of the ASME B31.8 Code.     

Investment decisions in electricity transmission in Argentina: The role of earmarked funds and gas pipeline expansions

This paper reexamines the problem of collective decisions of investment in electricity transmission in Argentina in the nineties. We summarize our previous results on the existence of a fundamental flaw in the evaluation of willingness-to-pay and on the need to consider the votes of groups of generators integrated through common ownership rather than individual generators. We discuss the workings of the SALEX account for financing expansions and confirm that the imperfect identification of voters could affect the evaluation of expansion projects. We also study an integrated model that considers two alternatives to electricity transmission: gas transmission and the location of generators; we show that location in the demand node voting against expansions in electricity transmission could be justified to maximize profits.     

Transitioning a bus transit fleet to hydrogen fuel: A case study of Knoxville Area Transit

The current climate crisis and recent world events, including the global economic crisis and growing concerns over the availability and cost of petroleum fuels, has sparked a global interest in developing alternative, sustainable, clean fuel technologies for the transportation sector. While a multitude of alternative fuel and vehicle technologies have been presented, hydrogen is considered by many as an option of choice. However, the mass-adoption of hydrogen presents many challenges, including appropriate refueling infrastructure supply transitions, consumer vehicle purchase behavior, and fuel costs. Early fleet adoption is one proposed strategy to transition hydrogen use in the transportation sector. Bus-transit demonstration projects have proven the technology, yet there has not been large-scale adoption by transit fleets. This paper addresses infrastructure, vehicle, and personnel needs to support the transition of a medium sized transit agency to full conversion to hydrogen fuel, using Knoxville Area Transit (KAT) as a case study. Specifically, requirements for hydrogen bus fleets, production, storage, refueling and maintenance facilities, and personnel are addressed as well as the transition strategy for implementing the technology.     

The role of buying consortia among SMEs in the electricity market in Italy

We model the electricity market in Italy, focusing on the impact of buying consortia among SMEs on the behaviour of the large electricity producers and sellers. We show that consortia may in certain circumstances produce a pro-competitive result, i.e. they may induce a reduction of prices not only for consortia members but also for firms not in the consortia.     

Economic impacts of higher oil and gas prices: The role of international trade for Germany

The analysis concentrates on direct and indirect price increases, induced shifts in international trade and structural changes in the oil importing economies. The paper at hand asks, whether a stabilizing effect via international trade and domestic structural change on the GDP of oil importing countries can be observed, if a permanent oil price increase occurs. At least for Germany, structural change from consumer goods to investment goods industry and an improvement of international competitiveness limit negative impacts of increased energy prices. Analysis is based on the extensive and disaggregated global GINFORS model and the detailed INFORGE model for the German economy.     

Hydrogen permeation and distribution at a high-strength X80 steel weld under stressing conditions and the implication on pipeline failure

Hydrogen permeation and distribution at pipeline welds is critical to integrity maintenance of the pipelines, especially for those made of high-strength steels. The situation becomes even more important under stressing conditions. In this work, metallographic characterization and micro-hardness measurements were conducted at an X80 steel weld. Potentiodynamic polarization and electrochemical hydrogen permeation testing were performance at various zones at the weld, along with numerical modeling of hydrogen distribution at the zones. The X80 steel contains a microstructure of bainite bundles and polygonal ferrite. There are more polygonal ferrite, fewer bainite and some segregated cementite at heat-affected zone (HAZ). The weld metal is featured with acicular ferrite and some grain boundary ferrite. HAZ softening occurs at the weld. The hardness of the weld metal, HAZ and base steel is about 290, 248 and 261 HV_0.2, respectively. There is the greatest corrosion current density, i.e., corrosion rate, at HAZ under both elastic and plastic stresses. An applied stress further increases the corrosion current density. Under the plastic stress of 1.1σ_ys (σ_ys is yield strength), the corrosion current densities of HAZ, base steel and weld metal are 41.04, 17.03 and 25.49 μA/cm², respectively. There are always the greatest hydrogen trapping density and the smallest hydrogen diffusivity at HAZ. Hydrogen, once penetrating the welded steel, tends to accumulate at the HAZ, compared with other two zones. When the welded steel is under stresses, especially a plastic stress (i.e., 1.1σ_ys), the hydrogen diffusivity and permeability decrease, while the subsurface hydrogen concentration and hydrogen trapping density increase remarkably. Plastic deformation favors the hydrogen permeation and trapping at weld, especially the HAZ, to elevate the susceptibility to hydrogen damage. The hydrogen distribution at different welding zones can be evaluated and determined by a developed modeling method.     

Analysis of electrochemical hydrogen permeation through X-65 pipeline steel and its implications on pipeline stress corrosion cracking

Electrochemical hydrogen permeation tests were performed to measure the hydrogen permeation current through the X-65 pipeline steel in the electrolytes simulating the soil conditions to initiate near-neutral pH stress corrosion cracking (SCC) in pipelines. The hydrogen permeation current was analyzed following the constant concentration model. It is shown that, AQDS, simulating the organic compound in the soil, inhibits hydrogen permeation by decreasing the sub-surface hydrogen concentration, while sulfide promotes hydrogen permeation by inhibiting the hydrogen recombination and thus increasing the sub-surface hydrogen concentration. The steel specimen is more susceptible to stress corrosion cracking in the soil solution with a higher sub-surface hydrogen concentration, indicating that hydrogen is involved in near-neutral pH SCC in pipelines. It is suggested that hydrogen promotes the cracking of the steel, accompanying with the anodic dissolution on the crack sides and at the crack tip.     

Thermal impact of the products pipeline on the crude oil pipeline laid in one ditch – The effect of pipeline interval

Numerical simulations are carried out to study the thermal impact of the cold products pipeline on the hot crude oil pipeline of the steady state. The pipelines studied are those used in the West Pipelines in China. The physical properties of North Xinjiang crude oil and those of 90# gasoline were used in this study. The effect of pipeline interval on the thermal impact is studied in details at various conditions.     

Transport interests and environmental regimes: The Baltic Sea transit of Russian oil exports

In the environmentally exposed Baltic Sea, a prolonged confrontation has set the transport interests of Russian crude oil against environmental interests, promoted by Russia's neighbours. During the 1990s all the Baltic littoral states – including Russia – collaborated well on marine environmental issues. When Russian oil exports accelerated after 1999, this environmental understanding broke down. Russian interests shifted as its oil income suddenly rose drastically. The confrontation peaked over a proposal to make the entire Baltic Sea into a particularly sensitive sea area (PSSA) under the International Maritime Organization (IMO). The proposal was adopted by the IMO in spite of Russian objections. The article shows how environmental interests trump transport interests in a manner that may not be sustainable. The case illustrates the need for environmental collaboration to be flexible in the face of shifting constellations of competing interests.     

The exploitation of Norwegian oil and gas

In this article Henrik Ager-Hanssen reviews Norway's experience of developing its oil and gas resources in the North Sea. His emphasis is on the way regulatory policies have changed since drilling started in 1966. Trends in exploration activity and investment are outlined and the impact of current production levels on Norway's GDP are examined. The effects of possible future production levels are also considered. Finally, the author discusses infrastructure problems and the prospects for further development.     

Risk and resilience in the Nigerian oil sector: The economic effects of pipeline sabotage and theft

Political unrest in the Niger Delta has long been viewed as a hurdle for extracting maximum value from Nigeria's oil resources. Recently, investors and policymakers have laid blame for sector under-performance on pipeline sabotage and theft, and sounded the alarm for an impending ‘oil crisis’. However, our understanding of the economic effects of social action against oil companies is incomplete. Rigorous analysis has not heretofore been offered as evidence for such dire futures. Despite the obvious risk of pipeline interdiction, price dynamics and aggregate production respond minimally to pipeline interdiction. Based on quantitative analysis of the relationship among price, production and pipeline interdiction from multiple data sources covering different time intervals (monthly data from 2005 to 2014 and annual data from 1999 to 2013), we find no evidence of significant effects of pipeline interdiction on production and a weak relationship between pipeline interdiction and Bonny light crude prices. Reported losses in product are substantial, but there is no evidence of statistically significant impacts on price or production in the aggregate. Explanations for this counterintuitive result are cast in terms of sector resilience. The implications of this finding for producer risk and the likelihood of an impending ‘oil crisis’ are discussed.     

A novel methodology for forecasting gas supply reliability of natural gas pipeline systems

In this paper, a novel systematic and integrated methodology to assess gas supply reliability is proposed based on the Monte Carlo method, statistical analysis, mathematical-probabilistic analysis, and hydraulic simulation. The method proposed has two stages. In the first stage, typical scenarios are determined. In the second stage, hydraulic simulation is conducted to calculate the flow rate in each typical scenario. The result of the gas pipeline system calculated is the average gas supply reliability in each typical scenario. To verify the feasibility, the method proposed is applied for a real natural gas pipelines network system. The comparison of the results calculated and the actual gas supply reliability based on the filed data in the evaluation period suggests the assessment results of the method proposed agree well with the filed data. Besides, the effect of different components on gas supply reliability is investigated, and the most critical component is identified. For example, the 48th unit is the most critical component for the SH terminal station, while the 119th typical scenario results in the most severe consequence which causes the loss of 175.61×10⁴ m³ gas when the 119th scenario happens. This paper provides a set of scientific and reasonable gas supply reliability indexes which can evaluate the gas supply reliability from two dimensions of quantity and time.     

Effect of hydrogen addition on the route preference in natural gas flow in regular,horizontal T-junctions

During the transport of natural gas through pipelines small amounts of condensate can be formed due to temperature and pressure changes. If this natural gas/condensate flow arrives at a regular, sharp-edged T-junction in the pipeline system an interesting phenomenon may be observed i.e. unequal phase splitting of gas and condensate. In this paper its has been shown that the addition of hydrogen into a natural gas stream results in a different splitting behaviour in comparison with the natural gas flow without hydrogen addition.     

A review of the oil and gas sector in Kazakhstan

Kazakhstan is endowed with significant oil and gas resources and is expected to become one of the world's top 10 oil producers within the next decade. The high cost of doing business in the country, however, means that Kazakhstan will need to improve its institutional framework to successfully compete for Western investment. A large degree of risk and uncertainty continues to plague the oil and gas sector as the government makes significant changes to the petroleum tax legislation and takes an aggressive approach in “rebalancing” contractual arrangements with industry. High levels of bureaucracy, regulatory burden, and corruption persist, and economic factors appear to be subordinated increasingly to geopolitical objectives aimed to strengthen relationships with China and Russia. The rapid pace of change and the high degree of uncertainty present significant challenges and risk to foreign investment. The purpose of this paper is to review the oil and gas sector in Kazakhstan and highlight recent developments in the petroleum legislation, business climate and government policy.     

燃气轮机压缩机组在西气东输管道上的应用

燃气轮机压缩机组在西气东输管道上获得了成功应用,积累了一定的经验,对大功率轻型燃气轮机驱动压缩机在管道输气上的推广可起到一定的借鉴作用.     

The production of crude oil and natural gas

This paper is directed at examining the impact of changing prices on the level of production of crude oil and natural gas in the United States. By using a cross-correlation test for unidirectional causality it is clearly demonstrated that, for both crude oil and natural gas, domestic production is affected by changing prices. The implications are clear. The decontrol of the price of crude oil and the deregulation of natural gas prices will lead to additional production in the near term.     

The political economy of trans-Pakistan gas pipeline project: assessing the political and economic risks for India

There is a growing realisation among Indian policy makers to consider the import of natural gas to address India's growing energy demand. Among many policy options to import natural gas, Indo-Iran overland pipeline option is considered to be effective and economical in addressing India's long-term energy demands. Such a pipeline would have to traverse Pakistani territory thereby necessitating a role for Pakistan in the pipeline project. Though security guarantees have been offered, India refuses to entertain the role of Pakistan in the project for a fear of its energy supply being disrupted in case of a military conflict with Pakistan. This paper argues that gas pipeline project is not only aimed at addressing India's energy concerns but also to further its strategic objectives. This paper contends that India, Iran and Pakistan do not have shared objective to make the overland project a political and commercial reality. India's stakes in the overland pipeline project are high as India's economic interests in the pipeline project are not in congruence with the politico-economic and strategic objectives of Iran and Pakistan.     

Strategic policy and the logistics of crude oil transit in Lithuania

This paper examines the crude oil transit market in Lithuania and the significant economic and political role played by Russia. Beginning with an analysis of the strategic and political role played by crude oil in Lithuania there follows a discussion of the policies followed by the Lithuanian authorities following independence in 1992 from the Former Soviet Union. A content analysis approach is taken to establishing the main policy issues that dominate the sector. This technique combines both quantitative and qualitative approaches to a review of published material on oil transit in Lithuania and acts as a means of assessing expert opinion on the issues involved. The results from this analysis will be used in developing policy initiatives for the sector. The paper ends with some suggestions for further applications of the techniques used to oil transit policy issues in the region.     

Dissociative adsorption of hydrogen and methane molecules at high-angle grain boundaries of pipeline steel studied by density functional theory modeling

Pipelines provide an economic and efficient means for hydrogen transport, contributing to accelerated realization of a full-scale hydrogen economy. Dissociative adsorption of hydrogen molecules (H₂) occurring on pipe steels generates hydrogen atoms (H), potentially resulting in hydrogen embrittlement of the pipelines. This is particularly important for existing pipelines transporting hydrogen in blended form with methane (CH₄). In this work, a density functional theory model was developed to investigate the dissociative adsorption of H₂ and CH₄ at high-angle grain boundaries (HAGB), a typical type of hydrogen traps contained in steels, and the stable adsorption configurations. Results demonstrate that the dissociative adsorption of both H₂ and CH₄ at the HAGB is thermodynamically feasible under pipeline operating conditions. Compared with crystalline lattice sites, the HAGB possesses the most negative free energy change, a lower energy barrier and the lowest H-adsorption energy, making the HAGB, especially the quasi three-fold site, become the most stable site for hydrogen adsorption. The saturation coverage of hydrogen at HAGB is calculated to be 1.33. The iron-H bonds are formed at the HAGB by charge consumption at Fe atoms and electron accumulation at H atoms, following a so-called electron hybridization mechanism. The CH₄ adsorption at HAGB affects the H₂ adsorption. Without pre-adsorption of CH₄, the hydrogen adsorption at the HAGB is more stable. Although an elevated CH₄ partial pressure decreases the thermodynamic tendency for H₂ adsorption, it cannot hinder occurrence of the H₂ dissociative adsorption.