scholarly journals Some advanced welding technologies applied for repair welding in power plants

10.30544/631 ◽  
2021 ◽  
Vol 27 (4) ◽  
pp. 473-487
Author(s):  
Zoran Dušan Odanović
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Electric Power ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Post Weld Heat Treatment ◽  
Low Alloy Steels ◽  
Repair Welding ◽  
Weld Heat

Steels are subjected to many time-dependent degradation mechanisms when they are applied in electric power plants. They are exposed to high temperatures, multi-axial stresses, creep, fatigue, corrosion, and abrasion during such services. Used under these threatening conditions, those materials could develop various damages or failures or even form cracks. Therefore, it is desirable to prevent in-service failures, improve reliability, and extend the plant's operational life. The efficiency of the electric power plant, among other processes, depends on effective maintenance. The paper presents the evaluation of advanced procedures and knowledge in the field of steel repair welding in the maintenance of the power plants. Most repair welding of low alloy steels requires high-temperature post-weld heat treatment (PWHT), but in certain repairs, however, this is not always possible. Application of the nickel-based filler metal could also be an alternative to performing post-weld heat treatment (PWHT). The repair work expenses could be reduced if the repair is performed on-site. The novel developed repair welding procedures presented in this paper were applied for emergency weld repairing of the steel pipelines in thermal power plant, repairing without disassembling the working wheel of the coal mill in thermal power plant and "on-site" repairing turbine shaft of the hydropower plant. For all the presented repair welding procedures, weldability analysis based on the analytical equations and technological ''CTS'' and ''Y'' tests to determine the sensitivity to cold and hot crack forming were applied. Tensile tests, absorbed energies tests, banding tests, and hardness measurements were performed on trial joints, which were used to develop and verify the applied methodologies. Presented advanced weld repair technologies enable repairs for a shorter time and at lower costs compared to conventional procedures.

Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants

2015 ◽  
Vol 1115 ◽  
pp. 503-508 ◽  
Author(s):  
Muhammad Sarwar ◽  
Mohd Amin bin Abd Majid
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Weld Metal ◽  
Creep Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Base Material ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.

Temper-Bead Weld by Underwater Laser Beam Welding

2009 ◽  
Author(s):  
Takeshi Fukuda ◽  
Rie Sumiya ◽  
Wataru Kono ◽  
Nobuichi Suezono ◽  
Masataka Tamura ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Nuclear Reactor ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Low Alloy Steels ◽  
Repair Welding ◽  
Alloy Steels ◽  
Underwater Laser ◽  
Weld Heat

In repair welding for nuclear reactor vessel, low alloy steels are affected by heat input during welding process. The conventional repair welding for wall steel constructions requires post weld heat treatment (PWHT) to achieve the desired microstructure properties. However, post weld heat treatment is very difficult for some structures in operating plants. In such case, temper-bead welding technique is available as a repair welding method. Temper-bead welding employs a multi-pass deposition of welding metal. Each layer of beads provides heat for thermal treatment of the previous weld bead or layer, which lowers hardness of the heat affected zone (HAZ) and improves mechanical properties like the toughness. Toshiba has developed underwater laser cladding and laser seal welding techniques for reactor components repair welding. In this report, some experimental results of laser based underwater temper-bead welding are presented.

Nonlinear Trend Analysis of Mill Fan System Vibrations for Predictive Maintenance and Diagnostics

2012 ◽  
Vol 58 (4) ◽  
pp. 351-356
Author(s):  
Mincho B. Hadjiski ◽  
Lyubka A. Doukovska ◽  
Stefan L. Kojnov
Keyword(s):  
Power Plant ◽  
Trend Analysis ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Balkan Peninsula ◽  
Predictive Maintenance ◽  
Nonlinear Trend ◽  
The Subject ◽  
The Given

Abstract Present paper considers nonlinear trend analysis for diagnostics and predictive maintenance. The subject is a device from Maritsa East 2 thermal power plant a mill fan. The choice of the given power plant is not occasional. This is the largest thermal power plant on the Balkan Peninsula. Mill fans are main part of the fuel preparation in the coal fired power plants. The possibility to predict eventual damages or wear out without switching off the device is significant for providing faultless and reliable work avoiding the losses caused by planned maintenance. This paper addresses the needs of the Maritsa East 2 Complex aiming to improve the ecological parameters of the electro energy production process.

Features of antibodies against benzo[a]pyrene formation in workers of coal mines and thermal power plants

2019 ◽  
pp. 9-14
Author(s):  
Ye. G. Polenok ◽  
S. A. Mun ◽  
L. A. Gordeeva ◽  
A. A. Glushkov ◽  
M. V. Kostyanko ◽  
...  
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Reference Group ◽  
Coal Dust ◽  
Thermal Power ◽  
Coal Mines ◽  
Serum Levels ◽  
Thermal Power Plants ◽  
Immune Reactions

Introduction.Coal dust and coal fi ring products contain large amounts of carcinogenic chemicals (specifically benz[a]pyrene) that are different in influence on workers of coal mines and thermal power plants. Specific immune reactions to benz[a]pyrene therefore in these categories of workers can have specific features.Objective.To reveal features of antibodies specifi c to benz[a]pyrene formation in workers of coal mines and thermal power plants.Materials and methods.The study covered A and G class antibodies against benz[a]pyrene (IgA-Bp and IgG-Bp) in serum of 705 males: 213 donors of Kemerovo blood transfusion center (group 1, reference); 293 miners(group 2) and 199 thermal power plant workers (group 3). Benz[a]pyrene conjugate with bovine serum albumin as an adsorbed antigen was subjected to immune-enzyme assay.Results.IgA-Bp levels in the miners (Me = 2.7) did not differ from those in the reference group (Me = 2.9), but in the thermal power plant workers (Me = 3.7) were reliably higher than those in healthy men and in the miners (p<0.0001). Levels of IgG-Bp in the miners (Me = 5.0) appeared to be lower than those in the reference group (Me = 6.4; (p = 0.05). IgG-Bb level in the thermal power plantworkers (Me = 7.4) exceeded the parameters in the healthy donors and the miners (p<0.0001). Non-industrial factors (age and smoking) appeared tohave no influence on specific immune reactions against benz[a]pyrene in the miners and the thermal power plant workers.Conclusions.Specific immune reactions against benz[a]pyrene in the miners and the thermal power plant workers are characterized by peculiarities: the miners demonstrate lower levels of class A serum antibodies to benz[a]pyrene; the thermal power plant workers present increased serum levels of class G antibodies to benz[a]pyrene. These peculiarities result from only the occupational features, but do not depend on such factors as age, smoking and length of service at hazardous production. It is expedient to study specific immune reactions to benz[a]pyrene in workers of coal mines and thermal power plants, to evaluate individual oncologic risk and if malignancies occur.

scholarly journals A GIS Based Approach for Radiation Risk Assessment Around a Thermal Power Plant Towards Adopting Remedial Measures

2018 ◽  
Author(s):  
Kajori Parial ◽  
S. Mukherjee ◽  
A. R. Ghosh ◽  
D. Sengupta
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Radiation Risk ◽  
Surface Radiation ◽  
Radiation Hazard ◽  
Remedial Measures ◽  
Ancillary Data ◽  
Risk Zone

Coal combustion in thermal power plants releases ash. Ash is reported to cause different adverse health hazards in humans and other organisms. Owing to the presence of radionuclides, it is also considered as a potential radiation hazard. In this study, based on the surface radiation measurements and relevant ancillary data, expected radiation risk zones were identified with regard to the human population residing near the Thermal Power Plant. With population density as the risk determining criteria, about 20% of the study area was at &lsquo;High&rsquo; risk and another 20% of the study area was at &lsquo;Low&rsquo; risk zone. The remaining 60% was under medium risk zone. Based on the findings remedial measures which may be adopted have been suggested.

SANITARY PROTECTION ZONES BY NOISE FACTOR FROM GAS DISTRIBUTION POINTS

Akustika ◽  
2021 ◽  
pp. 133-137
Author(s):  
Vladimir Tupov ◽  
Vitaliy Skvortsov
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Design Stage ◽  
Thermal Power Plants ◽  
Gas Distribution ◽  
Surrounding Area ◽  
Protection Zone

The power equipment of thermal power plants is a source of noise to the surrounding area. One of the sources of noise for the surrounding area are gas distribution points (GDP) of thermal power plants (TPP) and district thermal power plants (RTS). Noise from gas distribution points may exceed sanitary standards at the border of the sanitary protection zone. The article shows that the radiated noise from gas distribution points depends on the power of the thermal power plant (natural gas consumption) and the type of valves. Three types of valves used in gas distribution points are considered. Formulas are obtained for calculating the width of the sanitary protection zone for gas distribution points for thermal stations, depending on the consumption of natural gas (electric power of the thermal power plant) and the type of valve. It is shown that, depending on the valve used, the noise level at the border of the sanitary protection zone can either meet sanitary standards or exceed them. This allows at the design stage to select the required type of valve or to determine mitigation measures from hydraulic fracturing.

Supplier Selection Criterion for SSCM in Indian Thermal Power Plant

2019 ◽  
pp. 240-257
Author(s):  
Suchismita Satapathy
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Selection Criterion ◽  
Raw Material ◽  
Thermal Power Plants ◽  
Whole Process ◽  
Main Motive

All companies are dependent on their raw material providers. The same applies in the case of thermal power plants. The major raw material for a thermal power plant is the coal. There are a lot of companies which in turn provide this coal to the thermal power plant. Some of these companies are international; some are local, whereas the others are localized. The thermal power plants look into all the aspects of the coal providing company, before settling down for a deal. Some people are specifically assigned to the task of managing the supply chain. The main motive is to optimize the whole process and achieve higher efficiency. There are a lot of things which a thermal power plant looks into before finalizing a deal, such as the price, quality of goods, etc. Thus, it is very important for the raw material providers to understand each and every aspect of the demands of the thermal power plant. A combination of three methods—Delphi, SWARA, and modified SWARA—has been applied to a list of factors, which has later been ranked according to the weight and other relevant calculations.

The Characteristics of Weld Metal Zone Welded with Various Filler Metals

2013 ◽  
Vol 690-693 ◽  
pp. 2673-2677
Author(s):  
Kyung Man Moon ◽  
Mun Jin Nam ◽  
Yeon Chang Lee ◽  
Yun Hae Kim ◽  
Jae Hyun Jeong
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Weld Metal ◽  
Post Weld Heat Treatment ◽  
Fuel Oil ◽  
Corrosion Properties ◽  
Repair Welding ◽  
Piston Crown ◽  
Filler Metals ◽  
Weld Heat

Recently, the fuel oil of diesel engines of marine ships is being changed to heavy oil of low quality as the oil price is getting higher and higher. Therefore, the wear and corrosion in all parts of the engine, such as cylinder liner, piston crown, and spindle and seat ring of exhaust valves has predominantly increased. Thus, the repair welding of the piston crown is a unique method to prolong its life in a economical point of view. In this case, filler metals with a high corrosion and wear resistance are mainly being used for repair welding. However, the piston crown on the ships job site is often actually being welded with mild filler metals. Therefore, in this study, mild filler metals, such as E4301, E431316, and E4316, were welded to the SS401 steel as the base metal, and the corrosion properties of their weld metals with and without post weld heat treatment were investigated with some electrochemical methods in 0.1% H2SO4 solution. The weld metal welded with E4301 filler metal exhibited the best corrosion resistance among the filler metals in the case of no heat treatment, however, its resistance was considerably decreased due to the post weld heat treatment (annealing:625°C, 2hr). In particular, the weld metal of E4316 exhibited relatively a good corrosion resistance by the post weld heat treatment.

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