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Continuous earthmoving machines, such as bucket-wheel excavators (BWEs), are the largest mobile terrestrial machines exposed to the working loads of a periodic character. This paper aims to launch a new idea regarding the preservation of the load-carrying structures of these machines by the means of implementing a controllable frequency-controlled drive of the excavating device. Successful implementation of this idea requires a detailed analysis of the dynamic response of the load-carrying structure in order to determine the domains of frequency of revolutions of the bucket-wheel-drive electromotor (FREM) where the dynamic response of the structure is favorable. The main goal of the presented research was the development of a unique three-step method for the identification of the FREM ranges, where the vibroactivity of the load-carrying structure is within the allowed boundaries. A methodologically original study of the dynamic response was conducted on a unique dynamic model of the BWE slewing superstructure that allows for continuous variation of the FREM, i.e., of the frequency of excitation caused by the forces resisting the excavation. Validation of the spatial reduced dynamic model of the slewing superstructure and the corresponding mathematical model, as well as the overall approach to the determination of the dynamic response, were performed by the means of vibrodiagnostics under the real exploitation conditions. Application of the developed method has yielded: (1) the resonant-free FREM domains; (2) the FREM domains, where the structure is not exposed to the excessive dynamic impacts; and (3) the frequency ratio ranges defining the resonant areas. Additionally, the results of the research have pointed out that the resonant-free state represents a necessary but insufficient condition for the proper dynamic behavior of the BWE slewing superstructure.

An original method for validation of the number of buckets on the working device of a bucket wheel excavator based on the dynamic response of its slewing superstructure (SS) is presented. A set of 16 seemingly acceptable solutions which satisfied the rigid design restrictions, based on the preservation of the existing (a) bucket wheel drivetrain, (b) theoretical capacity, (c) characteristics of the excavated soil and (d) position of the superstructure centre of gravity (CoG), was analysed. Already on the basis of the limiting vertical and lateral accelerations of the bucket wheel centre, which represents a well-grounded indicator of its dynamic behaviour prescribed by the code DIN 22261-2, 14 out of 16 analysed design variants have been discarded, reducing the set of possible solutions to only two – the originally-designed variant (with 17 buckets), and the variant with 20 buckets. Conclusions on the validity of these two design variants were derived on the basis of the dynamic response analysis of the referent points of the SS. The analysis of the impact of soiling on the dynamic response of the SS has shown that negative dynamic effects, observed in the preceding analysis of the originally-designed solution, increase with the amount of the adhered material. Although the redesigned variant with 20 buckets has proven as the only suitable solution from the standpoint of dynamic behaviour of the SS, the results have to be assessed carefully due to the fact that the reduction of the mass of the bucket wheel steel structure by more than 14% leads to the appearance of unfavourable dynamic effects, even though the SS CoG position is preserved.

Tie-rods of the bucket wheel and counterweight booms are vital parts of the bucket wheel excavator slewing superstructure. This paper is dedicated to the problem of identifying the stress state of the critical cross-section ('net section') of the eye plates on these tie-rods. It presents the results of the experimental and numerical investigations carried out on the eyebar model. The results show the appearance of a plastic deformation in the zone near the contour of the hole even when the eye is subjected to the loads within the range of the permissible loads prescribed by the standard DIN 22261-2. Plastification in the eye net section occurs across the full thickness of the plate, but it does not jeopardize the integrity of the structure. The stress value in the eye net section, calculated in accordance with the standard DIN 22261-2, is significantly lower than the actual stress values around the hole and serves only as a comparative value for the static strength proof for the eye.

Stackers-reclaimers represent the mechanization backbone of high-capacity storages for granular materials. The paper presents the design of a gantry bucket chain stackers-reclaimer for handling of crushed gypsum, as well as the working technology, finite element strength calculation for the main substructures: the working device, the trolley and the gantry. Failureless operation of the presented stacker-reclaimer represent an indirect validation of not only the presented results, but also the entire project as well as the applied technology of manufacture and montage.

Identification of the basic parameters of static stability (BPSS) of the slewing superstructure is the key step in solving the problem of its static stability, as well as static stability of the entire bucket wheel excavator (BWE). Specificity of the slewing superstructure examined in this paper lies in the kinematic breakdown system (KBS) which prevents the loss of static stability on the counterweight side. Development of a unique method for the formation and two-step validation of the calculation models for this particular design concept was the main objective of the presented research. A two-step validation of the analytical models is conducted based on the experimental results. As the outcome, the final calculation model formed in such manner represents an accurate basis both for the proof of static stability and for the monitoring of the BPSS during exploitation. By comparing the results of the control weighing and the referent values of the final calculation model it was concluded that the existing double-walled bucket wheel represents a 'weak point' of the considered BWE.

A slewing superstructure (SS) represents a key functional subsystem of bucket wheel excavators (BWEs). Identification of its basic parameters of static stability (BPSS: weight and position of the center of gravity) is of equally crucial significance in design of a BWE and in its exploitation. The BPSS dominantly determine the static stability of a BWE SS and, coupled with stiffness, its dynamic response. This paper presents the results of research on the impact of the difference between the experimentally and analytically determined SS BPSS on the: (1) intensities of forces in the ropes of the bucket wheel boom hoisting mechanism; (2) maximum loads of the SS radiaxial slew bearing balls; (3) dynamic response of the SS. The presented research represents the initial stage in forming of the integral methodology for the assessment of impact of the mentioned differences on the key indicators which determine the lifespan and integrity, as well as reliability and safety of the SS of BWEs and related surface mining and material handling machines.

The design concept of temporary leaning of the gas oil storage tank bearing structure used during substitution of the worn out section of the bottom plates in the zone of the central column support is presented in the paper. On the basis of comparative analysis of the results obtained using finite element structural calculations of the designed state and the state of the central column leaning on the temporary supports, it was determined that by the implementation of the temporary support, the stress-strain state of the bearing structure, which corresponds to the designed stress-strain state of the construction, is obtained. Besides, the strength proof of the structure of temporary support including its welded joint to the central column is also presented in the paper.

This paper contains results of tests performed in order to determine mechanical properties of steel P460NL1, used as filler material during the execution of welded joints. Arc welding of samples from which the specimens were taken was carried out through the application of welding process 111, because it is one of the processes for the execution of pipelines for pressure equipment. Microspecimens with diameter of 1,5 mm were tested in order to determine tensile properties of material taken from the heat-affected zone and weld metal, while specimens with diameter of 6 mm were tested in order to determine tensile properties of parent material. Standard Charpy V-notch specimens were used in order to determine impact energy. Results of metallographic tests which refer to the structure of a pipe welded joint are also presented.

An original method for validation of the number of buckets on the working device of a bucket wheel excavator based on the dynamic response of its slewing superstructure (SS) is presented. A set of 16 seemingly acceptable solutions which satisfied the rigid design restrictions, based on the preservation of the existing (a) bucket wheel drivetrain, (b) theoretical capacity, (c) characteristics of the excavated soil and (d) position of the superstructure centre of gravity (CoG), was analysed. Already on the basis of the limiting vertical and lateral accelerations of the bucket wheel centre, which represents a well-grounded indicator of its dynamic behaviour prescribed by the code DIN 22261-2, 14 out of 16 analysed design variants have been discarded, reducing the set of possible solutions to only two - the originally-designed variant (with 17 buckets), and the variant with 20 buckets. Conclusions on the validity of these two design variants were derived on the basis of the dynamic response analysis of the referent points of the SS. The analysis of the impact of soiling on the dynamic response of the SS has shown that negative dynamic effects, observed in the preceding analysis of the originally-designed solution, increase with the amount of the adhered material. Although the redesigned variant with 20 buckets has proven as the only suitable solution from the standpoint of dynamic behaviour of the SS, the results have to be assessed carefully due to the fact that the reduction of the mass of the bucket wheel steel structure by more than 14% leads to the appearance of unfavourable dynamic effects, even though the SS CoG position is preserved.

Exploitation of bucket wheel excavators (BWEs) is accompanied by an increase of mass due to transport and adherence of a large amount of the material. Technical regulations do not account for the dynamic behaviour of BWEs. Such problems are analysed as quasi-static. A procedure and results of investigation of the influence of masses of the bucket wheel (BW) incrustation and soil in a blocked BW chute on the superstructure response are presented. Analysis of sensitivity of dynamic characteristics and the response to adherence of the material is conducted. The method and results can be used in the design stages of new and in reconstructions of obsolete BWEs.

Damaging of the carrying steel structure and embedding of the rejecting drum of the stacker conveyor occurred during the exploitation of the bucket-wheel reclaimer with the belonging stacker. The analysis of the cause and level of damaging led to the conclusion that damaged parts should be replaced by new ones and that methodology of repair should be based on the application of a suitable welding technology. This paper presents the methodology of repair welding performed during the replacement of the damaged carrying structure and embedding of the rejecting drum of the stacker conveyor which consist of steel sheets and profiles that’s based on the conceptual solution for damage repair through the use of program package ’Catia’ – V5 that enabled the creation of models and graphic documentation of structural parts that should be replaced by new ones. It should also be noted that geodetic survey of the lower belt of the stacker structure was performed after the substitution of damaged parts of the structure.

The method for validation of the number of buckets on the working device of a bucket wheel excavator from the aspect of dynamic behaviour of the system, partially presented in this paper, was developed on the basis of the original spatial reduced dynamic model of the bucket wheel excavator with two masts, which enables modal analysis and analysis of the dynamic response of the system for continuous variation of constructional parameters and parameters of excitation. The set of 16 seemingly acceptable solutions, all of which satisfied the rigid design restrictions which were: (a) use of the same bucket wheel drivetrain, (b) preservation of the theoretical capacity, (c) possibility of the excavation of soil of the fourth category and (d) preservation of the superstructure centre of gravity position, was analyzed. On the basis of limiting vertical and lateral accelerations, derived from dynamic coefficients prescribed by the code DIN 22261-2, of the bucket wheel centre, which for a proper geometrically-designed bucket wheel excavator structure represents a well grounded indicator of its dynamic behaviour, 14 out of 16 analyzed solutions were discarded, yielding the set of possible solutions to only 2, the originally designed one (with 17 buckets) and the solution with 20 buckets installed on the bucket wheel.

A bucket wheel with drive represents a vital subsystem of any bucket wheel excavator. A multidecadal experience in the exploitation and maintenance of bucket wheel excavators SRs 2000 has imposed a need for modernization and unification of the excavating devices of four of such machines, used for the excavation of overburden in Serbian open pit mines. This paper presents a portion of the research dedicated to the problems of strength and dynamic properties of the bucket wheel boom, static stability of the superstructure as well as installation of the unified design solution for the bucket wheel drive of the bucket wheel excavator SRs 2000. By installing a modernized design solution of the bucket wheel with drive, i.e. by the means of partial revitalization of the bucket wheel excavator, its exploitational life span is prolonged and, additionally, the level of reliability and availability of the overburden systems is increased, and a significant reduction in maintenance expenses is achieved.

During the rehabilitation of turbine and hydromechanical equipment at hydro power plant 'Djerdap 1' results of tests and researches carried out in order to analyze the condition of vital components and structures during service led to the conclusion that the components and structures could be made only if parameters of fracture mechanics were applied during the design and prototyping phase, because by doing so the occurrence of fatigue fracture and/or degradation of parent material and welded joints due to variable loading, corrosion, erosion and cavitation would be prevented, therefore the integrity of material would be maintained. Experimental determination of the fatigue crack propagation rate as an important property of development of the fatigue process during the action of the variable load, from the initial to the critical length, enables the prediction of the stable crack propagation period, or in other words of the service life of vital components and structures of turbine and hydromechanical equipment. Taking into account the fact that cracks are most severe of all defects, the results obtained for cracks could safely be applied for other types of defects which often occur in welded joints. This paper contains the methodological approaches for the assessment of integrity and evaluation of service life of components and structures of turbine and hydromechanical equipment during the design, prototyping and service period based on history of fatigue loading and application of fracture mechanics parameters.

Vertical Kaplan turbines, with nominal power of 178 MW and manufactured in Russia, have been installed in 6 hydroelectric generating units of hydro power plant ’Djerdap 1’. Experimental tests were carried out by non-destructive methods in order to determine the turbine condition during the rehabilitation of the hydro power plant. Lack of root penetration was detected in V40 welded joints between upper and lower sleeves and bodies of guide vane apparatus vanes. Height of the lack of root penetration was in the range between 5 and 15 mm, while the allowable height of the lack of root penetration is 3 mm, according to the technical conditions. The upper sleeves were made of cast steel 25L (in accordance with GOST 977), while lower sleeves were made of steel forging St 25 (in accordance with standards GOST 1050 for chemical composition and GOST 8479 for forgings).Methodology for the repair of non-penetrated welded joints between the sleeves and body of the guide vane apparatus vane was composed taking into account the results of ultrasonic testing. By repair methodology it is necessary to, due to the structural solution and service function of guide vane apparatus vanes, specify a large number of details, consider them carefully and carry them out in order to improve safety, because if some of them get overlooked, underestimated or incorrectly perceived, significant problems in turbine operation may occur.This methodology refers solely to the repair of damaged welded joints between sleeves and bodies of guide vane apparatus vanes.

During the revitalization of the hydroelectric generating station A4 at the hydro power plant 'Djerdap 1', all of its parts are subjected to non-destructive testing. Cracks are detected in cast part of generator rotor hub, in the flange area toward the turbine shaft. Cracks were 10-500 mm long (determined by magnetic particle tests) and 60-100 mm deep (ultrasonic tests). The generator rotor hub is made of cast steel 25L, in accordance with the standard 977-75. The welding/surface welding repair technology in the detected crack zones of the cast part of generator rotor hub includes a large number of details, due to the structural solution and generator rotor function in service. It was also necessary to provide the carefully undertaken activities in order to enable safe operation and continuous use of the rotor hub. Failing to notice, underestimation or incorrect perception of important details could cause significant problems in hydroelectric generating station operation. The paper, due to specifics of reparation technology, contains arranged preparatory activities for the procedure apart from the welding/surface welding technology. It is of importance to mention a huge amount of money savings, The manufacture of a new generator rotor would cost over 4 million EUR (generator mass is over 300 tonnes), not taking into account the time needed for its making (6-12 months), which is directly related to the amount of energy a hydroelectric generating station can produce during that period. This technology of repair welding is also applicable for other components and structures of the turbine and the hydromechanical equipment subjected to various causes of damage during exploitation.

Vertical Kaplan turbines were installed in 6 hydroelectric generating sets at "Djerdap 1", nominal power 178 MW, that were made in Russia. During the refurbishment of the hydroelectric generating set Al at the hydro power plant Djerdap 1, experimental non-destructive tests on all of its components were performed in order to determine the state of the turbine as a whole. During the testing the damages and cracks were detected on internal surfaces of cranks and sleeves of guide vane apparatus vanes, which were caused by turbine shaft vibrations. Cranks and sleeves were made of cast steel 25L, in accordance with the standard GOST 977. The repair methodology for damaged internal surfaces of cranks of guide vane apparatus vanes is presented in this paper. It was necessary, due to the structural solution used for the design of cranks and sleeves and their function during exploitation, to define a large number of details, carefully reconsider them and carry out all activities with extreme care in order to enable the safe operation and continuous use of cranks. Overlooking, underestimation or incorrect perception of important details could cause significant problems during turbine operation.

Columns of welded pipes in the oil and gas wells and pipelines for their transportation to consumers,fall into high responsible structures prone to corrosion and cracks. Therefore it is important to know the remaining strength of the pipes in the case of occurrence of any of the mentioned types of damage. Steels intended for the production of protective pipes for oil and gas drills are specified by the API 5CT standard. Premature failure or damaging of parts and components of welded pipes columns in wells, as well as pipelines for the transport of oil and gas is generally' caused by the simultaneous influence of a large number of technological, metallurgical, structural and exploitation factors. Therefore convenient structural solutions, which provide the mechanical safety of parts and the integrity of structures, can be realized only through total comprehension of their behavior in various operation regimes. The paper elaborates the importance of technical diagnostics for monitoring and analysis of protective pipes conditions in the wells and pipelines during the oil and gas transportations. Also, an analysis of the causes of failure of the pipes and pipelines is conducted and the importance of forming of database is considered.

Technical diagnostics of hydromechanical equipment, is based on testing procedures including the history of the exploitation with expert knowledge of structures and operating conditions, as well as, on the analysis of results performed by experts with appropriate experience and knowledge in design, exploitation, maintenance, reliability, fracture mechanics etc. Degradation of properties of the material and/or welded joints of hydro-mechanical equipment is being caused by the simultaneous influence of a large number of factors. First of all, it is thought of technological, metallurgical, structural and conditions of exploitation. In this paper, the selection of methodology for the rehabilitation of hydro-mechanical equipment is presented based on the previously conducted assessment of state of equipment using the nondestructive testing methods. Repair welding, repair of damaged surfaces by cold metallization, corrections of existing structural solutions of metallic components in order to improve their technical characteristics and extend the service life are presented.

Sprovedena je procena životnog ciklusa malog trakastog transportera. Analizirana je faza proizvodnje sa aspekata uticaja na životnu sredinu i potrošnje energije. Najveći uticaj na životnu sredinu u većini kategorija uticaja za osnovni model kategorija uticaja potiče od proizvodnje niskolegiranih čelika i potrošnje električne energije tokom faze proizvodnje, praćen uticajem transporta. U radu su takođe predloženi načini uštede energije u proizvodnoj praksi uz primenu adekvatnih tehnologija., A cradle-to-gate LCA analysis of a small belt conveyor was conducted. Manufacturing stage was analysed from the aspects of environmental impacts and energy consumption. The biggest environmental impact in majority of baseline impact categories is obtained from low-alloyed steel production and electricity consumption during the manufacturing stage, followed by impact of the transport. Ways for possible energy savings regarding manufacturing practice and technologies were proposed later on.

Buckets are a vital substructure of all digging machines, and are intended for the realisation of the fundamental machine function - soil excavation. This paper presents the results of the experimental-numerical investigation of the cause of the bucket wheel excavator SRs 470 buckets failure. The chemical composition and mechanical properties, the impact toughness, hardness, tendency to cracks and the microstructure were determined using appropriate tests. Experimental examinations of working and residual stresses were performed using strain gauges. The superposition of the experimentally determined working and residual stresses and the calculation of the total principal stresses were conducted using the originally developed procedure presented in this paper. The bucket working stress state was calculated by applying the linear finite element method. Conclusions based on the investigation results show that the main reasons for the buckets failure were the 'design-in defects' - oversights made during the procedures of geometrical shaping and material selection. Furthermore, high values of residual stresses, as well as the cold cracking observed on the welded joint of the knife and the bucket body, suggest that the 'manufacturing-in defects' also played a significant role in the failure. The superposition of influences of the 'design-in defects' and the 'manufacturing-in defects' has conditioned the appearance and propagation of long-term fatigue cracks, leading to the total destruction of the buckets. The fact that buckets' failure appeared due to oversights made during geometrical shaping, material selection and manufacturing further points to the importance of the critical approach implementation during the design phase of the earthmoving machines working devices.

Sensitivity analysis of the dynamic response of both the designed and the actual models of a slewing superstructure with two masts to the variation of the counterweight mass and the degree of accuracy of the approximation polynomials of the digging resistance was conducted in the paper. Spatial reduced dynamic models of the bucket wheel excavator SchRs 1600 were used as a basis for the presented investigations. Based on the comparative analysis of the calculation results, the following conclusions were drawn: (a) mass of the counterweight has a significantly higher influence on the maximum intensities of accelerations of the referent points than on the spectrum of natural frequencies, (b) the accuracy of approximations of the digging resistance and the maximum values of accelerations differ by an order of magnitude, for the approximation trigonometric polynomial of the same number of harmonics.

This paper presents a methodological approach for the assessment of service life of vital welded structures of a bucket-wheel excavator Sch Rs 650/5x24 ('Thyssen Krupp', Germany) boom, subjected to cyclic loading with a variable amplitude through the use of experimental tests carried out in order to determine operational strength and growth of a fatigue crack. Realized researches and results presented in this paper offer great possibilities for the analyses of behaviour of vital welded structures of the bucket-wheel boom. By the application of the measurement device with 8 channels for registration and processing of electric signals HBM Spider 8 and measurement tapes HBM 6/350xXY31 deformations were measured at vital welded structures of the boom in the area of the bucket-wheel, made of steels St 37.2 and St 52.3 in accordance with standard DIN 17100, or steels S235J2G3 and S355J2G3 in accordance with standard EN 10025-2. The objective of the test is to determine if there is a possibility of occurrence of plastic deformations or initial cracks due to fatigue at vital welded structures. Tests that refer to the growth of the fatigue crack located at the welded joint have been carried out by bending at three points with asymmetric load R = 0.5 (R = sigma(min) / sigma(max)) at the specimen with a single edge notch. Tests were performed through the use of controlled force, ranging between F-max and F-min at the high frequency pulsator 'Cracktronic', while obtainment of data regarding the crack growth was carried out through the use of measurement gauge ARM A-10.

The complexity of the slewing superstructure (SS) balancing problem derives from the changeability of its geometric configuration, the complexity of working conditions as well as multiple limitations of the possible set of solutions. Having in mind the fact that the existing reference literature does not fully specify the procedure of static stability proof, the aforementioned procedure is presented in detail for the first time in this paper. A major contribution is represented in the classification of the slewing superstructure models into two groups which were named: the 'a priori' model (designed image of the SS) and the 'a posteriori' model (actual image of the SS). The fundamental stages of the 'a posteriori' model development method are presented in the paper. The transformation and validation of the calculation model 'a priori' to the calculation model 'a posteriori' was conducted on the basis of weighing results. A calculation of the basic parameters of the bucket wheel excavator (BWE) superstructure was conducted for both analyzed models by using the in-house developed software. The 'a posteriori' models provide a reliable calculation of the SS static stability and may be used not only for static stability proof of the machine as a whole, but also for load analysis of substructures and elements of BWE and related surface mining machines, such as spreaders. Besides that, the previously mentioned models are of extreme importance for a successful and reliable exploitation and maintenence of the machine since they present the basis for adjustment and control of limiting winch rope forces values, periodic control of mass and center of gravity position, as well as for a possible reconstruction which would be conducted in order to realize better customization of the machine versus operating conditions.

This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the 'operating-in' defect (the malfunction of the limit switch) and the 'manufacturing-in' defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.

Рационалност и ефикасност у снабдевању убојним средствима огледа се у сврсисходном, организованом и оптималном коришћењу свих расположивих ресурса како у миру, тако и у рату..., Rationality and efficiency in the ammunition supply is reflected in the purposeful, organized and optimal use of all available resources both in peace and in war. Economy, as an unavoidable principle obliges consumers of ammunition, as well as other elements of the ammunition supply to use them to achieve the most favorable results...

Hydropower plants need to develop means of protection of turbine and hydromechanical equipment from undesirable occurrences, such as degradation of parent material and/or weld metal of parts and structures caused by stresses and unpredictable influence of vibrations, fatigue, corrosion, erosion and cavitation. Results of tests that refer to the cavitation resistance of turbine runner blades made of cast steel 08X15H4 pi M pi, in accordance with GOST standard are presented in this paper. For the testing of cavitation resistance, the ultrasonic vibration test method is used (with the stationary sample), for which it is necessary to measure the mass loss during specified time intervals, while the cavitation resistance of the material is being defined, taking into account the incubation period and cavitation rate. Scanning electron microscope analysis is carried out to study the morphology of sample damage due to cavitation. The obtained results show that the tested steel has a good cavitation resistance and that fatigue is the main failure mechanism.

Vertical Kaplan turbines, with nominal power of 176 A/ITY, manufactured in Russia, have been instal-led in 6 hydroelectric generating units of hydro power plant "Djerdap 1". Turbines were designed for the lifetime of 40 years due to the required structural solution and the inability of performing periodic inspections and state analyses. Welded structure of the upper ring of guide vane apparatus is made by welding four segments made of St 3 steel together, in accordance with standard GOST 977/88. Ring segments were welded by using submerged arc welding (SAW). During the rehabilitation of turbine A6 nondestructive and destructive tests were per formed on parent material and welded joints in order to carry out the state analysis and estimation of level and causes of eventual degradation of the structure of the upper ring of guide vane apparatus at hydro power plant Djerdap I. This paper comprises results of magnetic particle tests and ultrasonic tests per formed on welded jo-ints. By ultrasonic testing it was determined that there is a lack of root penetration in welded joints, as well as lamellar tearing in parent material. Analysis of the causes of parent metal degradation and occurrence of defects in welded joints of the upper ring of guide vane apparatus was carried out on the basis of results of experimental tests.

Cold metallization includes the powder or wire application on the cold surface of components by electric arc, gas, plasma, supersonic, gas-detonation method. It could be applied on all metals except on pure copper, but not on glass and non-metallic materials. Thickness of the layer which is being deposited ranges from 0.05 to 5 mm. Porosity of the layer is 3-15 %. Temperature of the parent material does not exceed 250°C, and therefore it sustains its mechanical properties. Taking into account the above mentioned, for the repair of damaged surfaces of components of turbine and hydromechanical equipment, the methodology of the electric arc technique was developed. At first, research regarding the possibility of application of cold metallization at damaged samples of metal sheets and pipes made of structural steel was carried out, and afterwards the same methodology was performed and confirmed during the repair of damaged surfaces of the flange at the horizontal Kaplan turbine with nominal power of 28 MW (Djerdap 2). Functional role of the flange, made of steel X5CrNi18-10, is to prevent the water from entering the enclosed space of the turbine shaft.

During the rehabilitation of the hydroelectric generating set A6 at hydro power plant ’Djerdap 1’, state analysis and integrity assessment were carried out for all vital components and structures. After the completion of non-destructive and destructive tests carried out on parent material and welded joints of the structure of the upper ring of guide vane apparatus as part of vertical Kaplan turbine runner, it was decided that it should be replaced with a new one, because parent material and welded joints were degraded beyond repair. Existing upper ring of guide vane apparatus was made of steel St 3, in accordance with GOST standard. New upper ring of guide vane apparatus was manufactured through the use of steel S 235, in accordance with DIN standard. During ultrasonic testing 6 mm high lack of root penetration was detected at the load carrying welded joint along the entire circumference of the guide vane apparatus. It should be noted that there is no possibility of restoring the welded joint, because the occurrence of deformations at the structure has to be avoided. In this paper the results of the check of load carrying capacity of welded joints are presented, taking into account all weakened cross-sections. Determination of load carrying capacity and fatigue strength were carried out in the usual way, as well as the stress state analysis performed through the use of finite element method in order to determine the influence of undercuts. Assessment of integrity and service life of the guide vane apparatus based on the influence of cracks on stress distribution and fracture mechanics parameters was also carried out.

As transportation machines, belt conveyors are part of intralogistics. Intralogistics is branch of logistics which is a much broader concept. In the field of bulk material handling belt conveyors are the most common means of transportation of goods. This research is dealing with the life cycle assessment (LCA) of a bucket wheel excavator (BWE) belt conveyor. It should establish methodology for LCA analyses of such short and similar types of belt conveyors and their possible eco and energy efficiency improvements. Generally, this methodology could be applied on any type of belt conveyors for bulk material handling as well as for solids transportation. Belt conveyor components were analysed separately within series of simplified LCAs which are presented in scientific papers. The first analysed component of the belt conveyor was the belt conveyor idler. The next component of belt conveyor subjected to analysis was the drive pulley. Further research was focused on analysis of the belt conveyor belting. The most recent analysed component is belt conveyor electric motor. Previously published paper related to conveyor design optimization can serve as source of definitions for such terms as sustainability, energy efficiency and energy savings. Latest research is dealing with summarized results from previous papers and with simplified LCA of a complete belt conveyor as well. It also contains recommendations, guidelines and possible solutions for eco and energy efficiency improvements of such type of belt conveyors. This series of simplified LCAs should provide a basis for further analysis and more comprehensive complete LCA of the belt conveyor with more powerful software tools, such as GaBi and SimaPro.

Department for Material Handling, Constructions and Logistics at the FME Belgrade has developed a test rig for steel cord belts. During the trials of the facility belt misalignment issue has occurred. The first measure in the direction of solving this problem was installation of side wheels for belt tracking. Since this didn't solve the problem, another solution is performed that included designing detachable drum rims for guiding the belt.