Snabdevenost važnijih tipova zemljišta Srbije osnovnim alkalnim elementima Ca, Mg, K i Na

In this paper results are presented of agrochemical and mineralogical analyses of 14 types of important soils in Serbia (Vojvodina and Central Serbia) and total content and availability of base alkali elements (Ca, Mg Na, K) are determined. Total element content was as follows: Ca 2.22%; K 1.77%; Na 0.85% and Mg 0.61%. Total content of alkali metals in the soils investigated and their variations within and between the soil types, is in very good/close correlation with contents of primary and secondary minerals as well as their rates of weathering. Taking in account the average availabilities the most abundant is calcium with 947 mg/100 g, whilst the averages of the other elements (Mg, K and Na) are quite similar and are about of 40 mg/100 g of soil. The results obtained have shown that the soils investigated are well to moderate provided with K, Ca and Mg and that their deficit could not be expected in plant nutrition, apart for some plants/cultures in the case of magnesium due to occasionally higher Ca/Mg and K/Mg ratios.U ovom radu je ispitivano 100 reprezentativnih uzoraka 14 tipova zemljišta Srbije (Vojvodina, Šumadija i Severno Pomoravlje) u pogledu ukupnog i pristupačnog sadržaja osnovnih alkalnih metala (Ca, Mg, K i Na). Takođe je prikazan i prosečan mineraloški sastav ispitivanih zemljišta. Nađeni su sledeći srednji ukupni sadržaji ispitivanih elemenata: Ca - 2,25%; K - 1,77% Na - 0,85% i Mg - 0,61%. Ukupni sadržaji ispitivanih alkalnih metala u našim zemljištima i njihova vapipanja između i unutar zemljišnih tipova u uskoj su vezi sa zastupljenošću određenih primarnih i sekundarnih minerala i njihovom otpornošću na raspadanje. Prema srednjim vrednostima za pristupačne sadržaje najviše ima kalcijuma (947 mg/100 g), a srednji sadržaji za ostale baze (Mg K i Na) su vrlo slični i kreću ce oko 40 mg/100 g. Dobijeni rezultati pokazuju da su ispitivana zemljišta dobro i srednje obezbeđena K, Ca i Mg i da se ne mogu očekivati njihovi deficiti za ishranu biljaka, osim za neke kulture u slučaju magnezijuma, zbog ponekad suviše povišenih odnosa Ca/Mg i K/Mg

The availability of base elements (Ca, Mg, Na, K) in some important soil types in Serbia

In this paper results are presented of agrochemical and mineralogical analyses of 14 types of important soils in Serbia (Vojvodina and Central Serbia) and total content and availability of base alkali elements (Ca, Mg Na, K) are determined. Total element content was as follows: Ca 2.22%; K 1.77%; Na 0.85% and Mg 0.61%. Total content of alkali metals in the soils investigated and their variations within and between the soil types, is in very good/close correlation with contents of primary and secondary minerals as well as their rates of weathering. Taking in account the average availabilities the most abundant is calcium with 947 mg/100 g, whilst the averages of the other elements (Mg, K and Na) are quite similar and are about of 40 mg/100 g of soil. The results obtained have shown that the soils investigated are well to moderate provided with K, Ca and Mg and that their deficit could not be expected in plant nutrition, apart for some plants/cultures in the case of magnesium due to occasionally higher Ca/Mg and K/Mg ratios

Piston middle position test, Variable Stator Vane Actuator of engine CFM56-3 /-5 /-7

Compressor is surely the most complex part of engine, and during projecting of engine, ensure safe operation of the compressor is very difficult job. In support of this is the fact that the most of accessories (sensors and actuators) are in connection with compressor, but two most important systems are VBV and VSV systems. In this work, we will observe VSV system, respectively VSV Actuator. Our research have a quest to decrees some remarked problems which occur during work on VSV Actuator, and of course we will offer a solution for remarked problem in term of adding another one point in test. Also, our suggestion is creating incoming inspection, pre-test inspection with the points to be listed in below

Recommendation for a new model of the maintenance system of turbine and hydromechanical equipment at the hydro power plant Djerdap 1

Turbine and hydro mechanical equipment at hydro power plant ’Djerdap 1’ is subjected to service conditions that lead to degradation of material of components and structures. Taking into account the rate of occurrence of failures (damages, accidents) and experience gained through long-term performing of tests it was established that main causes of material degradation are fatigue, corrosion, erosion and cavitation. Results of performed tests and researches carried out in order to identify the causes of material degradation, damaging and fracture of components and structures of turbine and hydro mechanical equipment during the rehabilitation of the hydro power plant ’Djerdap 1’ showed that material degradation, damages and fractures occur due to the simultaneous influence of a large number of technological, metallurgical, structural and exploitational factors and that convenient structural solutions which would ensure mechanical reliability of components and structural integrity could be achieved only through absolute knowledge of their behaviour under various regimes of operation. On the basis of those results new system for maintenance of components and structures of turbine and hydro mechanical equipment was recommended

Analysis of current state and integrity evaluation of the pipeline at hydro power plant "Pirot"

Hydro power plant Pirot, which was built in 1990, is an accumulation-derivative power plant, which consists of 2 above - ground vertical hydroelectric generating sets that contain Francis turbines with nominal power of 41,5 MW, manufactured in Czech Republic, a tunnel and a sunken pipeline with overall length of 2.030 m and diameter that ranges from 3.000 to 3.500 m. Pipes have been made of S275J2G3 steel. [1] Pipe wall is 22 mm thick. Maximum pressure of 2.5 MPa occurs in front of the turbine cover. [2] Pipeline has been designed and built without anchor blocks at curvatures, which is rarity elsewhere. Geodetic measurements have been conducted permanently from the day the assembly was finished and pipeline was put into service, both when pipeline is empty and unloaded by hydrostatic pressure and when it is full. Analysis of obtained data regards the movements along the pipeline route showed that from year 2003 there are significantly higher differences in movements comparing the situations when the pipeline is full and when it is empty in comparison with the previous period. Those differences primarily refers to tangential movements of vertices marked with numbers 6, 7 and 8, which, compared to the period until year 2002, are in the range from 3 mm for vertex 8 to 5 mm for vertex 6. Apart from geodetic measurements, the measurement of pipe diameter in 2 directions is also being carried out permanently. Those data show that from year 2003. the diameter in horizontal direction started to increase significantly, while at the same time the diameter in vertical direction started to decrease less significantly. This paper contains the analysis of current state and integrity evaluation of the pipeline as a whole on the basis of results of non - destructive tests performed on the vital butt - welded joint in the curvature area at chainage 1+263 m (visual testing, magnetic particle testing, penetrant testing, ultrasonic testing, radiographic testing, metallographic replication testing)

Repair welding methodology for the glasses of the Kaplan turbine runner at the hydro power plant Djerdap 1

Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been installed in 6 hydroelectric generating units at hydro power plant Djerdap 1. Hydroelectric generating sets have been designed for the service life of 40 years due to structural solutions and limited possibilities of performing periodic inspections and state analyses. During the rehabilitation of the hydroelectric generating sets, non-destructive tests were performed on all components and structures in order to complete state analysis. In this paper the damages and methodology of repair welding for damaged glasses, which are the integral part of the kinematic system of runner blades, are presented

Selection of steels for vital structures and turbine components of the hydro power plant ’Djerdap 1’

Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been installed in 6 hydroelectric generating units at ’Djerdap 1’. During the refurbishment of hydroelectric generating sets A4, A5 and A6, non-destructive and destructive tests were carried out on parent material and weld metal in order to complete the state analysis and assessment of damage level and causes of damage occurrence at vital structures and components, which showed that the selection of suitable material has a crucial role regarding the safe operation of hydroelectric power plants. This paper contains comparative results of mechanical tests performed in order to obtain mechanical properties of materials used for the fabrication of the upper rings of guide vane apparatus installed in 1973 and made of steel St 3 (GOST 977-88) and those recently made through the use of steel S 235 (EN 10025-2), as well as for turbine covers, made of steels S 355 NL (EN 10025-2) and S 355 NL + Z25 + N (EN 10025-3)

Use of Non-Destructive Tests for the Assessment of Integrity and Service Life of Hydro-Mechanical Equipment

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

Repair of damages that occurred on the welded joints at the body of guide vane apparatus vanes of the vertical Kaplan turbine

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

Influence of degradation of parent-material and welded joints on the integrity of the breeches pipe located at pipeline iii of hydro power plant ‘Perućica’

Hydro power plant ’Perućica’, which comprises 7 hydroelectric generating units, each with installed power of 330 MW, is the oldest hydro power plant in Montenegro and was put in service in 1960. This high pressure hydro power plant is a complex hydroenergetic system, which consists of a 3335 m long concrete tunnel, surge with a broadening and overflow and three steel pipelines with two-sided Pelton turbines with horizontal shafts installed.Five turbines have nominal power of 38 MW, while two have nominal power of 58,5 MW (307 MW overall). The biggest problem at hydro power plant ’Perućica’ refers to the parent material and weld metal of the breeches pipe 1A located at pipeline III. Significantly lesser problems were detected at parent material and weld metal of breeches pipes 7B, 8A and 8B. Pipeline and breeches pipes were made of microalloyed steel ’Nioval 47’ (steel mill ’Jesenice’). Stresses that occur at pipelines in service during the process of execution of functional tasks (stationary and dynamic loads) and during the disturbed process of exploitation (non-stationary dynamic loads) cause severe damaging of parent material and weld metal at structural components of breeches pipes (collars and anchors), thus endangering the integrity of pipeline structure as a whole. Role of the collar, which enables the leaning of the breeches pipe on the foundation, is to receive static and dynamic loads (mean pressure of up to 61 bar in pipeline axis, specific load that occurs due to the quantity of water in the pipeline, action of the force of gravity) and displacements which happen due to non-stationary dynamic loads that occur at the pipeline, while the anchor strengthens and balances the mass of the breeches pipe. In this paper the results of non-destructive tests carried out on parent material and weld metal (collar and anchor) of breeches pipes with designations 1A, 7A, 8A and 8B and results of destructive tests performed on parent material of the anchor are presented. Tests that were carried out include visual testing (VT), magnetic particle testing (MT) and ultrasonic testing (UT), while destructive tests included determination of chemical composition, tensile properties, impact energy and hardness. On the basis of results of test results it was determined that the main cause of occurrence of significant damages (degradation of parent material of the anchor and weld metal between the collar and anchor, as well as between the pipeline and the anchor) at the structure of the breeches pipe 1A of the pipeline III at the hydro power plant ’Perućica’ is the fact that the breeches pipe did not lean on the collar, as was predicted by design, but on the anchor which, due to the size of its cross-section, could not endure all loads that occur at the breeches pipe during service. Damages that occurred on parent material and weld metal of breeches pipes 7B, 8A and 8B are directly caused by flaws in welding technology and conditions of exploitation. Executed researches showed that degradation of parent material and weld metal does not influence the integrity of the pipeline III as a whole