scholarly journals Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

2021 ◽  
Vol 16 (59) ◽  
pp. 396-404
Author(s):  
Hryhoriy Nykyforchyn ◽  
Olha Zvirko ◽  
Myroslava Hredil ◽  
Halyna Krechkovska ◽  
Oleksandr Tsyrulnyk ◽  
...  
Keyword(s):  
Natural Gas ◽  
Hydrogen Embrittlement ◽  
Carbon Steels ◽  
Gas Distribution ◽  
Axis Ii ◽  
Steel Research ◽  
Hydrogen Assisted Cracking ◽  
Strength And Plasticity

A methodology of experimental research on hydrogen embrittlement of pipe carbon steels due to the transportation of hydrogen or its mixture with natural gas by a long-term operated gas distribution network is presented. The importance of comparative assessments of the steel in the as-received and operated states basing on the properties that characterize plasticity, resistance to brittle fracture and hydrogen assisted cracking is accentuated. Two main methodological peculiarities are pointed out, (i) testing specimens should be cut out in the transverse direction relative to the pipe axis; (ii) strength and plasticity characteristics should be determined using flat tensile specimens with the smallest possible thickness of the working part. The determination of hydrogen concentration in metal, metallographic and fractographic analyses have been supplemented the study. The effectiveness of the proposed methodology has been illustrated by the example of the steel research after its 52-year operation.

scholarly journals ЩОДО ВЕРИФІКАЦІЇ ЕКОНОМІЧНОЇ МОДЕЛІ ТАРИФУ НА РОЗПОДІЛ ГАЗУ ПРИНЦИПАМ СТИМУЛЮВАННЯ

2020 ◽  
pp. 24-28
Author(s):  
Столяр О. О.
Keyword(s):  
Natural Gas ◽  
Current Model ◽  
Incentive Regulation ◽  
Gas Distribution ◽  
Advantages And Disadvantages ◽  
The World ◽  
Selection Of

The purpose of this study is to determine the conformity (verification) of the current model of tariff formation for gas distribution service of gas companies to the principle of incentive regulation based on the selection of model elements and their comparison with the world successful experience. The method of verification based on the selection of model elements, the determination of the advantages and disadvantages of such a model, and the comparison of the latter, introduced at domestic gas companies on natural gas distribution, with the world's successful experience in regulating this issue. It is presented that this model does not fully comply with the principles based on long-term incentive regulation, which show its effectiveness in the world, which will be continued in the following studies.

scholarly journals A Gas Distribution Network Hydraulic Problem from Practice

2017 ◽  
Author(s):  
D. Brikić
Keyword(s):  
Natural Gas ◽  
Friction Factor ◽  
Gas Flow ◽  
Optimization Problem ◽  
Distribution Network ◽  
Gas Distribution ◽  
Pipeline Network ◽  
Hardy Cross ◽  
Selection Of

Accent is on determination of appropriate friction factor, and on selection of representative equation for natural gas flow under presented conditions in the network. Calculation of presented looped gas-pipeline network is done according to principles of Hardy Cross method. The final flows were calculated, for known pipes diameters and nodes consumptions while the flow velocities through pipes have to stand below certain values. In optimization problem flows are treated as constant, while the diameters are variables.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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