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1

Failure analysis during the operation of offshore oil and gas structures

Ben Nengjun, Vytyaz Oleg, Jin Xin, Hrabovskyi Roman, Kopei Bogdan

Nafta-Gaz

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2023

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R. 79, nr 8

529--536

EN

: Failures caused by offshore oil and gas structures operations are investigated. This work is based on the description and analysis of real case studies of accidents on offshore stationary and floating platforms; it combines foundational knowledge and current research on the latest developments in the field. It was shown that strength characteristics of offshore reinforced concrete and steel elements change during operation and cause the accumulation of defects and damages. It was established that corrosive wear, corrosion-mechanical processes, and crack-like defects are the decisive causes of element failure. It was shown that up to 60–75% of all damages to and failures of offshore engineering facilities' steel structures occur due to the corrosion-mechanical influence of an aggressive environment and force loads. This means that issues of corrosion-mechanical failure of such structures have become an industrial-scale problem. It thus allows us to draw the following conclusions: improvement of steel offshore drilling platforms (ODPs) maintenance system involves the development of new models and methods of managing the operational reliability of these structures, aimed at making decisions that take into account the crack resistance and fatigue-corrosion strength of steel ODPs in contact with the corrosive-active environment. Only on the basis of such scientifically and economically grounded models can rational strategies be shaped for carrying out revisions of the ODPs technical condition, ensuring the necessary level of their reliability during the operation period. This investigation can be very helpful to improve the design and construction of more reliable and durable offshore stationary and floating platforms.

PL

W artykule omówiono uszkodzenia powstające w trakcie eksploatacji podmorskich złóż ropy i gazu. Niniejsza praca opiera się na opisie i analizie rzeczywistych przypadków wypadków na morskich platformach stacjonarnych i pływających, łączy ona podstawową wiedzę z bieżącymi badaniami nad najnowszymi osiągnięciami w tej dziedzinie. Wykazano, że charakterystyki wytrzymałościowe elementów betonowych i stalowych konstrukcji morskich w trakcie eksploatacji zmieniają się i kumulują wady i uszkodzenia. Ustalono, że decydującymi przyczynami uszkodzeń elementów są zużycie korozyjne, procesy korozyjno-mechaniczne oraz defekty spękaniowe. Wykazano, że do 60–75% wszystkich uszkodzeń i wypadków stalowych urządzeń morskich powstaje w wyniku korozyjnego i mechanicznego działania agresywnego środowiska oraz obciążeń siłowych. Oznacza to, że kwestie korozyjnego mechanicznego uszkodzenia takich konstrukcji stały się problemem na skalę przemysłową. Na tej podstawie można wyciągnąć następujące wnioski: doskonalenie systemu utrzymania morskich stalowych platform wiertniczych wiąże się z opracowywaniem nowych modeli i metod zarządzania niezawodnością eksploatacyjną tych konstrukcji, ukierunkowanych na podejmowanie decyzji uwzględniających odporność na pękanie oraz odporność na korozję zmęczeniową stalowych platform wiertniczych stykających się ze środowiskiem korozyjno-aktywnym. Tylko w oparciu o tego typu, naukowo i ekonomicznie ugruntowane modele, można kształtować racjonalne strategie przeprowadzania przeglądów stanu technicznego morskich platform wiertniczych, zapewniające niezbędny poziom ich niezawodności w okresie eksploatacji. Badania te mogą być bardzo pomocne w ulepszaniu projektowania i budowy bardziej niezawodnych i trwałych morskich platform, zarówno stacjonarnych, jak i pływających.

2

Abrasive Wear Mechanisms of S235JR, S355J2, C45, AISI 304, and Hardox 500 Steels Tested Using Garnet, Corundum and Carborundum Abrasives

Szala Mirosław, Szafran Michał, Matijošius Jonas, Drozd Kazimierz

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 2

147--160

EN

Wear resistance is one of the main indicators of the reliability of machine parts. The selection of wear-resistant material should consider the operational environment and specific types of abrasive material. The steel abrasive wear resistance depends not only on its hardness and microstructure but also on the abrasive material's properties, such as hardness and particle morphology. This work aimed to determine abrasion wear mechanisms of a set of steels, i.e., S235, S355, C45, AISI 304 and Hardox 500, abraded by different types of grit i.e. garnet, corundum and carborundum. The abrasion tests were conducted using T-07 tribometer (rubber wheel method). Wear traces were examined with a scanning electron microscope (SEM), and a contact profilometer. SEM analysis revealed that apart from Hardox 500, ploughing and microfatigue were the dominant wear mechanisms. Microcutting was the main wear mechanism for Hardox 500 tested with carborundum (SiC). The highest mass loss was usually obtained for carborundum. The lowest wear resistance in garnet and carborundum was obtained for the S235JR and S235J2 steels and Hardox 500 tested with corundum. The effect of steel microstructure on the wear mechanism has been confirmed. AISI 304 austenitic steel abraded by carborundum grit, presented outstanding roughness parameters: Ra, Rz, RSm, Rk, Rvk and Rpk than other steels tested with carborundum. Steel hardness affects the morphology of the wear trace reducing the Ra and Rz roughness parameters. The effect of abrasive hardness and grain morphology on abraded surfaces has been stated. Contrary to fine grains of the hardest carborundum, coarse garnet grains caused high roughness parameters (Rk, Rpk and Rvk) determined in wear trace.

3

Phenomenological model of cavitation erosion of nitrogen ion implanted HIPed Stellite 6

Szala Mirosław

Advances in Materials Science

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2023

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Vol. 23, nr 1(75)

98--109

EN

Stellites are a group of Co-Cr-C-W/Mo-containing alloys showing outstanding behavior under cavitation erosion (CE) operational conditions. The process of ion implantation can improve the CE resistance of metal alloys. This work presents the elaborated original phenomenological model of CE of nitrogen ion implanted HIP-consolidated (Hot Isostatically Pressed) cobalt alloy grade Stellite 6. The ultrasonic vibratory test rig was used for CE testing. The nitrogen ion implantation with 120 keV and fluence of 5 × 1016 N+/cm−2 improves HIPed Stellite 6 cavitation erosion resistance two times. Ion-implanted HIPed Stellite 6 has more than ten times higher CE resistance than the reference AISI 304 stainless steel sample. Comparative analysis of AFM, SEM and XRD results done at different test intervals reveals the kinetic of CE process. The model includes the surface roughness development and clarifies the meaning of cobalt-based matrix phase transformations under the nitrogen ion implantation and cavitation loads. Ion implantation modifies the cavitation erosion mechanisms of HIPed Stellite 6. The CE of unimplanted alloy starts on material loss initiated at the carbides/matrix interfaces. Deterioration starts with cobalt matrix plastic deformation, weakening the carbides restraint in the metallic matrix. Then, the cobalt-based matrix and further hard carbides are removed. Finally, a deformed cobalt matrix undergoes cracking, accelerating material removal and formation of pits and craters' growth. The nitrogen ion implantation facilitates ɛ (hcp—hexagonal close-packed)) → γ (fcc—face-centered cubic) phase transformation, which further is reversed due to cavitation loads, i.e., CE induces the γ → ɛ martensitic phase transformation of the cobalt-based matrix. This phenomenon successfully limits carbide removal by consuming the cavitation loads for martensitic transformation at the initial stages of erosion. The CE incubation stage for ion implanted HIPed Stellite 6 lasts longer than for unimplanted due to the higher initial content of γ phase. Moreover, this phase slows the erosion rate by restraining carbides in cobalt-based matrix, facilitating strain-induced martensitic transformation and preventing the surface from severe material loss.

4

Water distribution and risk governance: data issues in view of development of risk-informed decision-making approach

Pietrucha-Urbanik Katarzyna, Tchórzewska-Cieślak Barbara, Eid Mohamed

Safety and Reliability of Systems and Processes

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2022

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Summer Safety and Reliability Seminar 2022

173--184

EN

The issues of failure risk assessment in water distribution systems are presented. Water supply network failure constitute a crucial issue in water distribution sector. Attention has been paid to the problem of risk assessment considering risk acceptance criteria. Besides, the water network failure indicators were assessed. The presented methods can be used to describe the general characteristics and the technical conditions of the water distribution system. The chapter is intended to draw the attention to the need for further technical and organisational improvement and for the standardization of the failure risk assessment in the water distribution systems.

5

Time-Spatial Analysis of the Functioning of the Water Distribution System in the Mathematical Modeling Process

Trębicka Agnieszka

Journal of Ecological Engineering

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2022

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Vol. 23, nr 6

90--99

EN

This paper presents the process of the temporal and spatial functioning of the water distribution system in the mathematical modeling process. The research was carried out on the Bialystok water network model with particular emphasis on the efficiency and energy efficiency of the pumping units located on the analyzed water distribution system (SDW). The calculations and calibration of the model were performed using the ISYDYW software, with particular emphasis on time and spatial distribution. Particular situations were analyzed, especially when the system operated in exceptional conditions, which most often resulted in failure, leading to a shortage of water supply, and thus energy losses of the pumping units. The obtained results allowed demonstrating the auxiliary role of the simulation method in determining and predicting the effects on the existing emergency states. Possible scenarios were prepared for the observed changes, both in the entire network and at the selected points of the pump systems. Assuming the duration of the failure, its consequences were determined and presented in the form of the indicators discussed.

6

Failure analysis of a high-speed induction machine driven by a SiC-inverter and operating on a common shaft with a high-speed generator

Breńkacz Łukasz, Bagiński Paweł, Adamowicz Marek, Giziewski Sebastian

Eksploatacja i Niezawodność

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2022

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Vol. 24, no. 1

177--185

EN

Due to ongoing research work, a prototype test rig for testing high speed motors/generators has been developed. Its design is quite unique as the two high speed machines share a single shaft with no support bearings between them. A very high maximum operating speed, up to 80,000 rpm, was required. Because of the need to minimise vibration during operation at very high rotational speeds, rolling bearings were used. To eliminate the influence of higher harmonics of supply voltage and current on the formation of torque oscillations on the shaft and excessive losses in the form of heat, a voltage source inverter with high switching silicon carbide (SiC) power transistors characterizing high precision of the output voltage generation with a fundamental harmonic frequency of several kilohertz has been used. During the first start-ups, it turned out that the system was not stable, and a failure occurred. The paper presents the consequences that may arise when a machine operating at a speed of about 70,000 rpm fails. The article contains pictures of a generator failure that occurred at a high rotational speed.

7

Gas turbine reliability estimation to reduce the risk of failure occurrence with a comparative study between the two-parameter Weibull distribution and a new modified Weibull distribution

Djeddi Ahmed Zohair, Hafaifa Ahmed, Iratni Abdelhamid, Kouzou Abdellah

Diagnostyka

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2022

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Vol. 23, No. 1

no. art. 2022107

EN

Responding to the needs of quality and robustness of analysis and management of degradation of equipment, to increase their life cycle and to expand these facilities to become more and more sophisticated and agronomic. This work proposes a contribution to increase the survival of a gas turbine, installed in a gascompression plant, with a comparative study between the two-parameter Weibull distribution. A new modified Weibull distribution was proposed also to reduce the risk of occurrence of failure in this rotating machine. A Statistical analysis and validation on the synthesis of turbine's reliability data and failures were considered, with a particular focus on the use of this data to increase the availability of this type of machine. So, developing a maintenance plan based on their reliability indices for scheduled inspections.

8

Cavitation erosion phenomenological model of MCrAlY and NiCrMoNbTa metallic coatings deposited via the HVOF method

Szala Mirosław

Tribologia

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2021

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nr 4

45--55

EN

The work describes the phenomenological model of cavitation erosion (CE) elaborated for MCrAlY (where M = Co, Ni or Co/Ni) and NiCrMoNbTa. Coatings were deposited via the HVOF method from CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa feedstock powders. CE tests, conducted according to ASTM G32 standard, indicate that MCrAlYs have a 50% higher maximum erosion rate and twice lower CE resistance than the NiCrMoNbTa coating. CE kinetics of coatings were comparatively studied, combining the mass loss, erosion rate, roughness changes of the eroded surface with microstructure, and mechanical properties of the coatings. Results of SEM analysis of damaged coatings allow identifying the mechanism of CE. In the case of both types of coatings, the erosive damage is initiated at the removal of loose splats, cracking at the border splats and peeling off the coating material, and surface pitting. However, NiCrMoNbTa, due to higher ductility and microstructure homogeneity, presents lesser surface pitting contrary to the MCrAlYs, which have multiphase microstructure higher hardness and consequently was prone to cracking, resulting in the formation of craters and higher surface roughening. The CE mechanism of MCrAlYs was dominated by the brittle mode, while the NiCrMoNbTa coating has mainly a ductile damage behaviour.

PL

W pracy opisano fenomenologiczny model erozji kawitacyjnej (EK) opracowany dla powłok MCrAlY (gdzie M = Co, Ni lub Co/Ni) i NiCrMoNbTa. Powłoki wytworzono metodą HVOF z komercyjnych proszków CoNiCrAlY, NiCoCrAlY i NiCrMoNbTa. Testy erozji kawitacyjnej, przeprowadzone zgodnie z normą ASTM G32, wskazują, że MCrAlY mają o 50% wyższą prędkość erozji i dwukrotnie niższą odporność EK niż powłoka NiCrMoNbTa. Kinetyka erozji kawitacyjnej powłok została poddana analizie porównawczej syntetyzującej utratę masy, szybkość erozji, zmiany chropowatości erodowanej powierzchni z mikrostrukturą oraz właściwościami mechanicznymi badanych powłok. Wyniki analizy SEM uszkodzonych powłok umożliwiły zidentyfikowanie mechanizmu EK. Uszkodzenie erozyjne powłok inicjowane jest w wyniku usuwaniu słabo umocowany cząstek materiału, pękaniu na granicach lameli następnie usuwaniu materiału i tworzeniu wżerów. Jednak NiCrMoNbTa ze względu na wyższą ciągliwość i jednorodność mikrostruktury wykazuje mniejsze wżery powierzchniowe w przeciwieństwie do MCrAlYs, które cechują się wielofazową mikrostruktura o wyższej twardości i w konsekwencji są podatne na pękanie, co powoduje powstawanie dużych wżerów i wyższe chropowacenie powierzchni. Mechanizm erozji kawitacyjnej powłok MCrAlY jest zdominowana przez kruche pękanie, natomiast w przypadku powłoki NiCrMoNbTa dominuje plastyczne odkształcenie.

9

Evaluation procedure for blowing machine monitoring and predicting bearing SKFNU6322 failure by power spectral density

Castilla-Gutiérrez Javier, Fortes Garrido Juan Carlos, Davila Martín Jose Miguel, Grande Gil Jose Antonio

Eksploatacja i Niezawodność

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2021

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Vol. 23, no. 3

522--529

EN

This work shows the results of the comparative study of characteristic frequencies in terms of Power Spectral Density (PSD) or RMS generated by a blower unit and the SKFNU322 bearing. Data is collected following ISO 10816, using Emonitor software and with speed values in RMS to avoid high and low frequency signal masking. Bearing failure is the main cause of operational shutdown in industrial sites. The difficulty of prediction is the type of breakage and the high number of variables involved. Monitoring and analysing all the variables of the SKFNU322 bearing and those of machine operation for 15 years allowed to develop a new predictive maintenance protocol. This method makes it possible to reduce from 6 control points to one, and to determine which of the 42 variables is the most incidental in the correct operation, so equipment performance and efficiency is improved, contributing to increased economic profitability. The tests were carried out on a 500 kW unit of power and It was shown that the rotation of the equipment itself caused the most generating variable of vibrational energy.

10

Reducing Melt Surface Turbulence by Employing Surge and Filter in a Conventional Non-Pressurizing Gating System: Simulation and Experiment

Baghani Amir, Kheirabi Ali, Bahmani Ahmad, Khalilpour Hamid

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

397--405

EN

Tensile strength of aluminum castings has been improved by employing surge and filter in a conventional non-pressurizing gating system. For this purpose, three non-pressurizing bottom-gating systems were designed where the first design was a simple design with no filter and no surge, in the second design filter and in the third one surge was added to the end of runner. Tensile strength, Weibull module, scanning electron microscopy, chemical analysis, and melt pattern during the mold filling were thoroughly analyzed to compare these three designs. it was observed that employing filter and surge in the gating system reduces flow kinetic energy and consequently avoid surface turbulence and air entrainment, which leads to castings with fewer defects and higher reliabilities. Finally, it found that appropriate use of surge in the running system can be as effective as employing a filter in reducing melt front velocity.

11

Influence of the type of adhesive on the properties of the GFRP composite adhesive joint, determined on the basis of the static T-peel test

Kubit Andrzej, Katrňák Tomáš, Pytlowany Tomasz

Advances in Materials Science

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2021

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Vol. 21, nr 3(69)

63--74

EN

The article presents the results of experimental studies determining the influence of the type of adhesive on the static strength properties of the Glass Fiber Reinforced Polymer (GFRP) composite joint determined on the basis of the T-peel test. As part of the static tests on peeling joints, a comparison of peak load and stiffness for individual joints was made. The fracture surfaces were also analyzed, showing various failure mechanisms. It was shown that the variant of joints made with the Enguard BP72A polyester adhesive was characterized by the highest strength properties with a mean peak load of 836.73 N.

12

Supervised probabilistic failure prediction of tuned mass damper-equipped high steel frames using machine learning methods

Farrokhi Farshid, Rahimi Sepideh

Studia Geotechnica et Mechanica

|

2020

|

Vol. 42, nr 3

179--190

EN

In this study, firstly, the behavior of a high steel frame equipped with tuned mass damper (TMD) due to several seismic records is investigated considering the structural and seismic uncertainties. Then, machine learning methods including artificial neural networks (ANN), decision tree (DT), Naïve Bayes (NB) and support vector machines (SVM) are used to predict the behavior of the structure. Results showed that among the machine learning models, SVM with Gaussian kernel has better performance since it is capable of predicting the drift of stories and the failure probability with R2 value equal to 0.99. Furthermore, results of feature selection algorithms revealed that when using TMD in high steel structures, seismic uncertainties have greater influences on drift of stories in comparison with structural uncertainties. Findings of this study can be used in design and probabilistic analysis of high steel frames equipped with TMDs.

13

Methods for identifying threats of critical infrastructure systems within Baltic Sea region

Tchórzewska-Cieślak Barbara, Pietrucha-Urbanik Katarzyna, Szpak Dawid

Journal of Polish Safety and Reliability Association

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2019

|

Vol. 10, No. 1

149--166

EN

In the analysis of the operation of critical infrastructure systems it is important to perform the analysis of the safety of the operation. The daily operation of such systems is inherently associated with the occurrence of various types of random undesirable events. Therefore, in the paper the matrix and logical trees methods used in the analysis of the risk of threats in critical infrastructure systems within the Baltic Sea, were presented. The analysis and assessment of the protection of technical system was performed using the FMEA method (Failure Mode and Effect Analysis). As to analyse the cause and effect of undesirable events the method of Bayes' theorem and Java Bayes program were implemented, which allows to identify the probability of the event occurrence.

14

The use of the FMEA method in the analysis and assessment of technical systems safety

Tchórzewska-Cieślak B., Pietrucha-Urbanik K., Szpak D.

Journal of Polish Safety and Reliability Association

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2018

|

Vol. 9, No. 3

95--100

EN

The analysis and assessment of the protection of technical system was performed using the FMEA method (Failure Mode and Effect Analysis). The FMEA method allows the product or process to be analysed, to identify weak points, and then introduce corrections and new solutions to eliminate sources of undesirable events. The developed methodology was presented on the example.

15

The causes of the damage to the bearing rope – failure analysis

Peterka Pavel, Krešák Jozef

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 2

231--236

EN

In our laboratory we quite often experience problems with the operation of steel ropes. There is a range of causes related to lifetime problems of ropes. These problems are related to poor quality of input material used for wire production, mixing of different wire strengths in the rope construction, improper roping of the rope into the hoist system, improper rope operation, improper rope design for a particular type of operation as well as unfair practices of vendors. The subject of the article is the analysis of the rope showing the combination of a large number of the above factors leading to the damage of the rope. During the operation of the cargo cableway, the hauling ropes were damaged in a very short time. The Z wires from the surface layer of the rope started to release from the rope. Subsequently, the wires were unwinding from the layer, they created visible protuberant waves, they were braking and dropping out from the rope. The hauling rope had to be replaced. Than the samples were taken from the rope in order to find out the cause of the rope damage. Mechanical, metallographic and fractographic measurements were performed on the rope. The metallographic and fractographic measurements revealed the material defects of the wires of the rope caused during manufacturing of the Z wires from the surface layer of the hauling rope. The mechanical tests revealed differences in the tensile strength grade the operator required compering to the tensile strength grade the vendor declared. The above mentioned problems unambiguously show that it is appropriate to introduce a mechanical control of the rope properties in advance to its deployment. Checks must be performed by an independent testing laboratory. This procedure overprices inputs needed for the rope replacement. On the other hand, it can reduce the costs when a poor quality rope is deployed. Some of our customers have already adopted this approach. It helped to the increase in the safety of the operation of the mechanisms and it eliminated the problems with exchange and climes on bad quality ropes.

16

Experience of the Crane Steel Wire Ropes Non-Destructive Tests

Peterka Pavel, Krešák Jozef, Vojtko Marek

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 4

157--163

EN

The non-destructive tests (NDT) of the steel wire ropes put on the crane pulley blocks comprise more than a half of our NDT services. The intensive utilization of cranes often leads to critical situations endangering health and safety at work. The operators are forced to provide safety use of the cranes due to new cranes constructions, new construction of the block pulley and put on the new steel wire rope constructions. The NDT tests of the crane steel wire ropes are coordinate by the Standard ISO 4309. We have experienced only the crane steel wire ropes with an individual wire rope core during our NDT tests so far. The visual NDT test usually used is ineffective to the steel wire ropes with this construction. Based on our previous experience it can be confirmed that surface ruptures are produced after the disintegration of wires inside of a rope; it often leads to the rope abruption during its operation. The reduction of the pulley block dimensions often leads to the problem of the multi-axis rope bending. This kind of the rope line in the pulley block causes the increase of the fretting fatigue of the wires and the rope strands. The same type of the stress is created when the dead ends of the rope are badly constructed.

17

Conveyor Failure Diagnostics using Sound Visualization Technique

Moravec M., Badida Miroslav, Jamborova Miroslava, Badidova Anna

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 4

144--150

EN

Sound visualization methods and techniques are currently applied in various fields to identify and locate individual sources of noise. Conveyor systems are used in various industrial plants. Conveyors require regular inspection and maintenance. In some operations, conveyor systems are difficult to access for the maintenance purposes. During their operation, conveyor systems contribute to increasing the noise levels. The increased noise emitted by a conveyor may signal the failure of a certain part of the system. Such failures can be identified by a sound visualization device and contribute to an effective maintenance of conveyor systems. The paper analyzes specific conveyor systems and identified potential failures of these conveyor systems by using sound visualization methods.

18

Reduced failure rate of hydrogen compressor valves through optimized cylinder lubricating oil supply

Białek P.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

|

2017

|

no. 3

83--89

EN

Hydrogen reciprocating compressors are essential elements of technological systems in refineries. The methodology of failure analysis and basic methods of hazard analysis are described. The biggest percentage share of reciprocating compressor component failures falls on valves. Images of typical working valve failures in reciprocating compressors are described. Failure mechanisms taking place in valves are characterized, resulting from excessive doses of oil lubricating compressor cylinders. Causes of the compressor functional unit failures are systematically listed. The problem under consideration is the methodology of research aimed at the identification of causes, solutions to the problem and the effects of introduced changes.

PL

Wskazano na sprężarki tłokowe wodoru jako bardzo istotne elementy systemów technologicznych rafinerii. Opisano metodykę analizy uszkodzeń oraz scharakteryzowano podstawowe metody analizy zagrożeń. Wskazano iż największy udział procentowy uszkodzeń elementów sprężarek tłokowych przypisuje się zaworom roboczym. Wskazano i opisano typowe obrazy uszkodzeń zaworów roboczych sprężarek tłokowych. Scharakteryzowano mechanizmy uszkodzeń zaworów roboczych powstałych w wyniku dozowania zbyt dużych ilości oleju smarującego cylindry. Usystematyzowano przyczyny uszkodzeń zespołów funkcjonalnych sprężarek tłokowych. Przedstawiono rzeczywisty problem, metodykę badań mających na celu określenie przyczyn problemu, oraz jego rozwiązanie i efekty wprowadzonych zmian.

19

A numerical investigation of the influence of the material microstructure on the failure mode of metal ceramic composites

Pandi P., Bolzon G.

Engineering Transactions

|

2016

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Vol. 64, iss. 4

547--553

EN

Metal failure is often initiated by strain localization in narrow bands. In metal matrix composites, the occurrence and the consequences of this phenomenon are influenced by the material microstructure. This dependency has been numerically investigated by considering periodic and quasi-periodic arrangement of ceramic fibers in a metal matrix, with reinforcement content varying between 10% and 50% in volume. The constitutive response of the metal has been simulated by the widely used GTN (Gurson-Tvergaard-Needleman) continuum damage-plasticity model with evolution law based on local porosity. The onset of failure for the composite has been identified with the critical growth of micro voids that induce softening at the macro scale. An extensive study has been performed in order to distinguish the effects of the material microstructure, the role of the imperfections and the influence of the simulation details. The main results of this investigation are summarized in this paper.

20

Analiza awaryjności trzonów sterowych na przykładzie remontów urządzeń sterowych w Szczecińskiej Stoczni Remontowej Gryfia

Banaszek A.

Autobusy : technika, eksploatacja, systemy transportowe

|

2016

|

R. 17, nr 12

775--780

PL

W artykule przedstawiono analizę awaryjności trzonów sterowych , jednego z najważniejszych elementów urządzeń sterowych na statkach morskich.. Analizę przeprowadzono na podstawie remontów urządzeń sterowych przeprowadzanych w Szczecińskiej Stoczni Remontowej SSR Gryfia w latach 2002-2007. Przedstawiono rozwój historyczny konstrukcji urządzeń sterowych. Przeprowadzono klasyfikację najczęściej spotykanych rodzajów mechanizmów sterowych na statkach morskich. Przeanalizowano awaryjność poszczególnych rozwiązań sterów i trzonów sterowych. Pokazano technologie napraw trzonów sterowych w SSR Gryfia.

EN

The analysis of starring rods damaged problem, one of the most important elements of steering devices has been presented in the paper. The analysis was executed on the base of maintenance operations made in Szczecin Repair Shipyard Gryfia in 2002-2007 years. The history of the ships steering devices constructions was shown. The classification of different kinds of steering devices used on sea vessels was made. The analysis damages of different solutions of steering devices and steering rods was presented. Technology of steering rods maintenance used in Szczecin Repair Shipyard Gryfia was desriebed.