Specific features of the influence of hydrogen on the properties and mechanism of fracture of the metal of welded joints of steam pipelines at thermal power plants

2006 ◽  
Vol 42 (4) ◽  
pp. 451-460 ◽  
Author(s):  
O. Z. Student ◽  
A. D. Markov ◽  
H. M. Nykyforchyn
Keyword(s):  
Welded Joints ◽  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants

scholarly journals Structural-&-Phase Condition and the Damageability of the Welded Joints of Steam Pipelines at Thermal Power Plants

2021 ◽  
pp. 56-63
Author(s):  
Vitaly Dmitrik ◽  
Igor Kasyanenko ◽  
Alexandr Krakhmalyov
Keyword(s):  
Service Life ◽  
Welded Joints ◽  
Power Plants ◽  
Low Cycle Fatigue ◽  
Thermal Power ◽  
Economic Effect ◽  
Structural Phase ◽  
Initial Structure ◽  
Thermal Power Plants ◽  
Phase Condition

The authors studied the interrelation between the type of structure and the damage rate of the welded joints of steam pipelines made of the heat-resistant pearlitic steels that were operated for a long time, i.e. more than 270 thousand hours in the conditions of creepage and low-cycle fatigue. The purpose of this research was to establish the interrelation between the structural-&-phase condition of the metal used for welded joints of the elements of steam systems and their damageability rate for the service life of welded joints exceeding 270 thousand hours. During the studies, the methods of optical and electron microscopy were used according to the requirements of the guideline documentation and also the methods that are used for the determination of mechanical properties. The level of their reliability has been substantiated and the residual life has been determined. To impart functional performances to welded joints we used well-known methods that were appropriately emended according to the structural changes of above joints. Such changes condition the conversion of the original structure of welded joints into the ferrite-carbide mixture. The availability of the conversion process of the initial structure on the thermal action zone sections (TAZ) of welded joints has essential distinctions due to a different disposition of metal to its own damageability. On the whole, the welded joints are damaged more intensively in comparison to the basic metal of steam pipelines. The analysis of the structural state of welded joints in the steam pipelines of thermal power plants as for the extension of their service life results in a considerable economic effect. Understanding the fact that the metal deterioration in welded joints adheres mainly to the fragile mechanism we managed to establish the level of their damageability that demands the renewal of damaged welded joints. We believe that the damageability level of welded joints that tots up to 0.25 or 0.35 of the volume of their TAZ section should be considered as critical for the service life exceeding 270 thousand hours. The damaged welded joints should be renewed throughout the time period of 15 to 20 thousand hours as soon as the specified damageability level is attained.

scholarly journals Prerequisites for developing an advanced welding technology for repair of worn elements of steam-conducting systems

2021 ◽  
pp. 108
Author(s):  
Tatyana Syrenko
Keyword(s):  
Chemical Composition ◽  
Welded Joints ◽  
Power Plants ◽  
Thermal Power ◽  
Economic Effect ◽  
Thermal Power Plants ◽  
Repair Work ◽  
Welding Technology ◽  
Conducting Path ◽  
Mechanized Welding

The main disadvantage of standard technologies of welding steam pipelines of thermal power plants is that they can allow the presence of defective structures close to the defective ones in the metal of the seam and in the sections of the HAZ. In this regard, the question arises about the development of a new technology that will provide the appropriate structure and properties that will increase the service life of steam pipelines and get a significant economic effect. Goal. The goal is improvement of the technology of welding pipelines of thermal power plants based on the study of the features of the formation of welded joints operating in Creep conditions. Methodology. The level of wear of the elements of the Steam-conducting path was estimated taking into account the provisions of the regulatory documentation of metallographic analysis, determination of chemical composition and properties, as well as the degree of their deformation. Results. It is revealed that welded joints are characterized by initial structural heterogeneity, which is closely related to long-term strength, ductility and impact strength. For example, at different sections of a welded joint, there is a different intensity of transition of alloying elements and, accordingly, a different type of structural component can be formed. The proposed technology of welding repair of damaged elements of steam pipelines using mechanized welding in CO2+Ar provides for the production of welded joints with a higher level of uniformity of structure, chemical composition and properties. Scientific novelty and practical significance. The welding technology has been improved, which includes developing the modes for performing repair work by mechanized welding in an Ar + CO2 environment of steam pipeline samples with a depth of ≥ 20 mm and a width of ≥ 30 mm, and differs from the known ones by using linear energy welding of 1.2–1.5 MJ/m.

FINDING SECURITY PARAMETERS FOR THERMAL POWER PLANTS – A CASE STUDY OF NTPC KORBA

2013 ◽  
Author(s):  
Raj Sekhar Choudhury ◽  
◽  
Sutapa Das ◽  
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Thermal Power Plants

On the prospect of introduction of plasma ignition in power boilers

2019 ◽  
Vol 12 (1) ◽  
pp. 22-28
Author(s):  
V. Ye. Mikhailov ◽  
S. P. Kolpakov ◽  
L. A. Khomenok ◽  
N. S. Shestakov
Keyword(s):  
Russian Federation ◽  
Solid Fuel ◽  
Power Plants ◽  
Thermal Power ◽  
Fuel Oil ◽  
Solid Fuels ◽  
Thermal Power Plants ◽  
Plasma Ignition ◽  
The Russian Federation ◽  
Capital Construction

One of the most important issues for modern domestic power industry is the creation and further widespread introduction of solid propellant energy units for super-critical steam parameters with high efficiency (43–46%) and improved environmental parameters. This will significantly reduce the use of natural gas.At the same time, one of the major drawbacks of the operation of pulverized coal power units is the need to use a significant amount of fuel oil during start-up and shutdown of boilers to stabilize the burning of the coal torch in the variable boiler operating modes.In this regard, solid fuel TPPs need to be provided with fuel oil facilities, with all the associated problems to ensure the performance (heating of fuel oil in winter), reliability and safety. All of the above problems increase both the TPP capital construction costs, and the electricity generating cost.A practical solution to the above problems at present is the use of a plasma technology for coal torch ignition based on thermochemical preparation of fuel for combustion. The materials of the developments of JSC “NPO CKTI” on application of plasmatrons in boilers of thermal power plants at metallurgical complexes of the Russian Federation are also considered.Plasma ignition systems for solid fuels in boilers were developed by Russian specialists and were introduced at a number of coal-fi red power plants in the Russian Federation, Mongolia, North Korea, and Kazakhstan. Plasma ignition of solid fuels is widely used in China for almost 30% of power boilers.The introduction of plasma-energy technologies will improve the energy efficiency of domestic solid-fuel thermal power plants and can be widely implemented in the modernization of boilers.During the construction of new TPPs, the construction of fuel oil facilities can be abandoned altogether, which will reduce the capital costs of the construction of thermal power plants, reduce the construction footprint, and increase the TPP safety.

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