Steel Hull Research Articles

Сравнительный анализ методов расчета нагрузки масс на начальных стадиях проектирования судна по разделу «Корпус металлический» на примере танкера ледового плавания

«Нагрузка масс» является одним из ключевых документов, входящих в состав проектной документации. Максимально точный расчет всех разделов нагрузки масс судна является важной составляющей проектного процесса, от ранних до заключительных этапов проектирования судна. Известно большое количество методов приближенного определения массы корпуса судна на начальных стадиях проектирования, однако результаты расчетов по этим методам часто дают большое расхождение с фактическими данными, получаемыми путем определения массы корпуса по документам рабочего проекта или по результатам кренования и взвешивания судна после спуска. В настоящей статье приведено описание наиболее распространенных приближенных методов определения массы металлического корпуса судна (как с применением, так без применения данных судна-прототипа), а также сравнение результатов расчета по этим методам с фактической массой корпуса нефтеналивного судна ледового плавания класса AFRAMAX, полученной путем прямого расчета. Для решения поставленной задачи использовалась трехмерная модель корпуса, выполненная в программе «Rhinocerous» и результаты процедуры «Набора по правилам», выполненной в программном комплексе «САПР-К» на основе требований Общих Правил МАКО для навалочных и нефтеналивных судов. Результаты работы могут быть полезными проектантам при выборе адекватного метода расчета массы металлического корпуса на начальных стадиях проектирования судна. “Calculation of Weights” is one of the key documents included in the design documentation. The most accurate calculation of all sections of the vessel's weights breakdown is an important component of the design process from the early to the final stages of vessel design. There are a large number of methods for approximate determination of the mass of a ship's hull at the initial stages of design, however, the results of calculations using these methods often give a large discrepancy with the actual data obtained by determining the mass of the hull from detailed design documents or from the results of inclining and weighing experiment for the vessel after launching. This article provides a description of the most common approximate methods for determining the mass of the steel hull (both with and without the use of data from a reference vessel), as well as a comparison of the calculation results using these methods with the actual mass of the hull of an AFRAMAX class ice-going oil tanker, obtained by direct calculation. To solve the problem, a 3-d model of the hull was used, made in the «Rhinocerous» program and the results of the prescriptive hull design procedure, carried out in the «CADS-HULL» software package based on the requirements of the IACS Common Rules for bulk carriers and oil tankers. The results of the work can be useful to designers when choosing an adequate method for calculating the mass of a steel hull at the initial stages of ship design.

Uticaj emulzionog premaza na otpornost na koroziju ploča trupa od mekog čelika u prirodnoj morskoj vodi

The corrosion resistance of mild steel, used to make hull plates in ship technology, in sea water before paint coating [Nippon paint SUMO XTRA durable exterior emulsion coating (emulsion coating)] and after paint coating has been measured by electrochemical studies such as polarisation study and AC impedance spectra. It is observed that after paint coating, the corrosion resistance of mild steel hull plates increases. Polarization study reveals that after paint coating, the linear polarization resistance increases and corrosion current decrease. AC impedance spectra reveal that in the presence of paint coating charge transfer resistance value increases, impedance value increases, phase angle increases and double layer capacitance value decreases. The corrosion inhibition efficiency was greater than 99%. The hull plates made of mild steel may be coated with durable exterior emulsion coating (emulsion coating). This will control the corrosion of the hull plates in the sea water. There will be increase in the life time of the hull plates.

Structural integrity assessment of a full-scale adhesively-bonded bi-material joint for maritime applications

The present study proposes a comprehensive integrity assessment approach for a full-scale adhesively-bonded bi-material joint for maritime applications. The joint represents a cross-section of the bond-line connection of a ship with a steel hull and a sandwich composite superstructure. The full-scale joint consists of a sandwich composite core adhesively bonded to two U-shaped steel brackets. The joint was subjected to a quasi-static loading profile including 6 load cycles up to the final failure. Each load cycle was followed by a dwell segment holding the joint at the maximum displacement for 30 s and then unloading to 50% of the maximum displacement. Three Structural Health Monitoring (SHM) techniques including Acoustic Emission (AE), Fiber Optic Sensor (FOS), and Digital Image Correlation (DIC) were employed during the test to assess the damage state of the joint. Moreover, a Finite Element Model (FEM) was developed to simulate the evolution behavior of different damage mechanisms in the joint and the FE results were compared against the experimental findings. The obtained results showed that the integration of all the employed techniques could successfully detect the damage initiation, assess the severity of the damage, localize the critical regions of the joint, and distinguish the different damage mechanisms.

Simulacija torzijske vibracije signala dvotaktnog brodskog dizelskog motora pri normalnom paljenju i zatajenju paljenja

The article presented the modelling of torsional vibration signal of marine diesel engine, MAN B&W 6S46MC-C7, installed in general cargo ships 34000 DWT, built at Pha Rung Shipyard (Vietnam). The authors imitated the torsional vibration signal, based on the established signal modelling when diesel engine works normal firing and mis-firing state, according to the Class Regulation Rules for new building steel hull ships when calculating and measuring the torsional vibration of marine diesel propulsion shaft-line system. The authors used Matlab software to imitate the torsional vibration signals in the real time domain and then converted them into the frequency order by Fast Fourier Transform (FFT).

Effect of Different Contents of WC on Microstructure and Properties of NiCrMo Coatings Prepared by PTA

During the service process of the mechanized fishing boat, its low carbon steel hull and parts are extremely susceptible to Cl− erosion and seawater scouring, which cause a decrease in strength and lead to failure. To increase its service life and reduce maintenance costs, coating protection technology is widely used. In order to solve the problem of poor adhesion between paint coating and substrate and low strength of metal coating, NiCrMo-WC coatings with different WC contents (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) were prepared on the surface of Q235 substrate by plasma cladding technology. The coatings were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy spectrum analysis (EDS), etc. Its phase formation rule, microstructure and element distribution were studied. Microhardness test and electrochemical corrosion test were carried out. The study found that the 20 WC coating has the highest average hardness (563.1 HV). It is about 3.25 times of the Q235 substrate. It has the lowest friction, wear rate and lower friction coefficient, showing the best wear resistance. The 15 WC coating has the lowest self-corrosion current density (3.4934 × 10−7 A/cm2) and the lowest corrosion rate (0.0041 mm/a), which is only 3.7% of the corrosion rate of Q235 steel.

80 years later: Marine sediments still influenced by an old war ship

Historic shipwrecks form an anthropogenic landmark in marine environment, yet their influence on the local geochemistry and microbiology remains largely unexplored. In this study, sediment and steel hull samples were taken around the V-1302 John Mahn, a World War II shipwreck, at increasing distance from the wreck, in different directions. Polycyclic aromatic hydrocarbons (PAH’s), explosives, and heavy metal levels were determined and related to the microbial composition. Benz(a)anthracene and fluoranthene remain present at the mg kg-1 level, probably originating from the coal bunker. These PAH’s indicate that the wreck is still influencing the surrounding sediments however the effects are very dependent on which side of the wreck is being studied. Known PAH degrading taxa like Rhodobacteraceae and Chromatiaceae were more abundant in samples with high aromatic pollutant content. Moreover, sulphate reducing bacteria (such as Desulfobulbia), proven to be involved in steel corrosion, were found present in the biofilm. This study shows that even after 80 years, a historic shipwreck can still significantly steer the surrounding sediment chemistry and microbial ecology.

Modeling and Characterization of a ReBCO HTS Degaussing Demonstrator

The magnetic modelling and experimental validation of a superconducting degaussing system for maritime vessels is discussed. Degaussing coils compensate for the distortion in the earths’ magnetic field by the magnetized steel hull of a ship, thus rendering it ‘invisible’ for magnetic field sensors. Whereas typical power requirements with copper coils are of the order of 100 kW, a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Re</i> BCO HTS degaussing system in principle allows to reduce this by an order of magnitude. In order to validate such efficiency estimates and to demonstrate the required hardware, a table-top test setup was realized with magnetic ship steel. The vessel-imitating cylindrical demonstrator is equipped with six degaussing coils, grouped in three sets that act in two different directions, with each set consisting of one copper and one <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Re</i> BCO coil, the latter one equipped with a sub-cooled forced-flow liquid nitrogen system. Static magnetic field measurements are reported and compared to both analytical and numeric finite element models. The results illustrate how even relatively simple analytical models can be used as a powerful tool to extrapolate design parameters and thus to predict the power requirements of large-scale degaussing systems.

Did Steam Make Shipping Safer? Evidence from the British Coastal Bulk Trades

The transition from sail to steam had more profound effects than any other development in the recorded history of merchant shipping. In combination with iron and steel hulls, steam power enabled ships to become larger, more reliable and more efficient, with far reaching effects on the shipping industry and world trade. But the question has rarely been asked, did the change make ships safer? This was of immediate concern to those working aboard the ships, but also to those who operated, financed, employed and insured them. It might be expected that an iron or steel hull, propelled independently of wind and tide, would be in less danger from accidental loss than a wooden ship largely at the mercy of the elements, but evidence is largely lacking. This paper reports a survey comparing the loss rates of sailing and steam-powered vessels in the British coastal bulk trades, where sail and steam were doing similar work in the same geographical setting. Although steam vessels were marginally safer, the difference in rates of loss are not as great as expected, and reasons for this are discussed, with particular focus on those who worked aboard them or had a financial or commercial interest.

Seawater-Based Triboelectric Nanogenerators for Marine Anticorrosion

The liquid-solid triboelectric nanogenerator is broadly studied for its self-powered sensing and blue energy harvesting, thanks to its low wear and highly efficient contact. However, the corresponding research studies focusing on deionized-water liquid-solid triboelectric nanogenerators (DL-TENGs) and seawater-type liquid-solid TENGs (SL-TENGs) are rarely being carried out at present. Here, a SL-TENG is fabricated by applying a dielectric film as the organic coating and coated and uncoated steel hull as the two electrodes. Based on the reasonable material selection of the dielectric film, the SL-TENG showed excellent performance, which benefits from the good triboelectrification performance and weak ion adsorption effect. In addition, compared with commercial marine anticorrosive coatings, the friction coefficient of the SL-TENG with the seawater can be reduced 43.8%, which is significantly beneficial to reduce the sailing resistance of ships. More importantly, the uncoated steel electrode can obtain a high potential in highly corrosive seawater, which can enable it to perform the function of marine anticorrosive agents. Our finding provides a potential strategy to evade the marine anticorrosion of ships.

Uticaj premaza na koroziju ploča trupa od mekog čelika u prirodnoj morskoj vodi

The corrosion resistance of mild steel (used to make hull plates in ship technology) in seawater before paint coating (Nippon paint, weatherbond advance) and after paint coating has been measured by electrochemical studies such as Polarisation study and AC impedance spectra. It is observed that after paint coating, the corrosion resistance of mild steel hull plates increases. Polarization study reveals that after paint coating, the linear polarization resistance increases and corrosion current decreases. AC impedance spectra reveal that in the presence of paint coating charge transfer resistance value increases, impedance value increases, phase angle increases and double layer capacitance value decreases.

К вопросу использования алюминиевых электродов для контроля защищенности от коррозии стальных корпусов судов и кораблей

The article highlights the test results of a non-standard reference electrode made of a stripped of insulation strand of aluminum wiring, which were conducted on board an auxiliary marine vessel PM-15. The potential of the ship’s hull was measured at the same control point using three reference electrodes: silver chloride electrode No. 1; aluminum electrode No. 2; aluminum electrode No. 3. The vessel’s hull potential was measured over five days. All three reference electrodes were used daily. With the help of each electrode, fifty parallel measurements of the potential of the ship’s hull were carried out with a time interval between measurements of 5 seconds. To assess the accuracy of the measurement results, they were processed statistically. The factors that must be taken into account in the development of technologies for manufacturing non-standard reference electrodes are listed: using available inexpensive materials; avoiding expensive equipment in manufacturing the reference electrode; eliminating complex methods of storage of reference electrodes on ships. There has been given a diagram of measuring electrical circuits including the steel hull, a bulwark, a multimeter, a clamping device, switches, a silver chloride reference electrode, aluminum wires, etc. The results of the study can be used on sea-going vessels to organize the control of the protective effect of the hulls of ships and vessels in the absence of standard reference electrodes.

К вопросу использования цинковых электродов для контроля протекторной защиты судов и кораблей

The article focuses on the importance of organizing the ship operators training, who control the operation of systems protecting the sea vessels from corrosion. There are presented the results of a scientific research - control of the operation of the tread protection system of the steel hull of an auxiliary marine vessel (floating workshop PM-15), which is in a long-term standby mode. The potential difference between the ship's hull and two reference electrodes was measured at a given control point. The control measurements have been carried out using the reference electrodes: silver chloride reference electrode recommended for use by regulatory documents and zinc reference electrodes (not recommended by regulatory documents for sea vessels). There have been made 50 parallel control measurements. The time interval between parallel measurements was 5 seconds. Control measurements were performed within 5 days from 07.02.2020 to 07.14.2020. The accuracy of the control measurements was assessed in accordance with regulatory requirements. It has been stated that both reference electrodes provide high accuracy of control measurements; the results of control carried out with the help of zinc reference electrodes are highly stable. It has been inferred that zinc reference electrodes can be used on Russian ships to control the tread protection of the ship's hull and can be recommended for using by ship crews for training ship operators of ship corrosion protection systems.

Estimation of Ship’s Magnetic Signature Using Multi-Dipole Modeling Method

Underwater magnetic signature of sea vessel is an important characteristic in mine threat estimation. Traditionally, the vessel's signal is measured with the help of stationary magnetic range equipped with bottom-mounted magnetic sensors. However, such a range may be unavailable near vessel's operating area. In this work, we investigate a capability of underwater magnetic signature estimation basing on the results of overhead magnetic mapping of the vessel by a portable total field magnetic sensor installed on a light aerial platform. A magnetic model of the vessel is represented by an array of point magnetic dipoles distributed over steel hull and clusters of ferromagnetic equipment. The model parameters are estimated by fitting the calculated magnetic field produced by the model to a measured overhead magnetic anomaly map. Once these parameters are determined, the vector magnetic field produced by the object may be calculated at any point both in “near” and “far”-field zones. To confirm this approach, we built a steel model ship in a scale of around 1:100. Dedicated setup enables us to measure the magnetic field produced by the model from below and from above. Our experimental results show less than 20% difference between the magnetic signature predicted by the model and measured directly below it. Such accuracy is quite acceptable for this specific application and, therefore, the proposed method can be treated as a viable alternative to traditional magnetic ranging.

Mode II fracture of an MMA adhesive layer: Theory versus experiment

Thick adhesive layers have potential structural application in ship construction for the joining of a composite superstructure to a steel hull. The purpose of this study is to develop a mechanics model for the adhesive fracture of such lap joints under shear loading. Modified Thick-Adherend-Shear-Test (TAST) specimens made from a MMA-based adhesive and steel adherents are designed and fabricated. Crack initiation and growth of these joints is measured and monitored by Digital Image Correlation (DIC). An attempt is made to use a cohesive zone model to predict the magnitude of shear strain across the adhesive layer both at crack initiation and at peak load, and to predict the extent of crack growth as a function of shear strain across the adhesive layer. The ability of a cohesive zone model to predict several features of specimen failure is assessed for the case of an adhesive layer of high shear ductility.

Environmental impacts of steel ship hulls building and recycling by life cycle assessment (LCA)

ABSTRACT Serious environmental impacts of a ship's life cycle occur during building and end-of life phases. In this study, data gathered from the related sites in Turkey for steel hull building and its reverse process of steel hull recycling phases for different type of ships have been assessed by using SimaPro 8.2.3 software and CML-IA methodology to determine impact categories of abiotic depletions, acidification, eutrophication, global warming, ozone depletion, human toxicity, freshwater and marine aquatic ecotoxicities, terrestrial ecotoxicity and photochemical oxidation. Results from life cycle inventories and impact assessment have shown that 85% of the related impacts caused by shipbuilding and the complexity of the ship type have significant effects on these impacts. The paper has also shown that LCA is a valuable tool which can help stakeholders for a sustainable industries.

Effects of the standoff distance on hull structure damage subjected to near-field underwater explosion

The near-field underwater explosion poses a great threaten to marine ships by introducing both local and overall damage on their hull structures. In this paper, a series of near-field underwater explosion experiments were carried out on the mimic steel hull structures to investigate the effects of the standoff distance on their dynamic behavior. Special attention was paid on their deformation process and failure modes. After that, a fluid-solid coupling algorithm was implemented in establishing a finite element (FE) model to simulate dynamic response of the hull structures under a near-field underwater explosion. The numerical results showed a good agreement with the experimental data. A standoff distance threshold was found to result in the maximum structural deformation. The deformation magnitude was monotonically decreased by either increasing or decreasing the standoff distance from the threshold value.

Analysis of Possibility of Repairing Welding of Selected of the Steam Turbines

Abstract The article presents the results of the study on the possibilities of repair by welding methods of exploitation steam turbine bodies. Two hull were investigation after a lifetime of more than 200.000 hours. Repair welding study were carried out on the L17HMF cast steel body in the immediately after exploitation condition, whereas the L21HMF cast steel body underwent a revitalization after the exploitation, and then the welding repair research were performed. On the material taken from the L17HMF cast steel hull, welding repairs were made by welding the previously cut four grooves measuring 200 mm 50 mm 50 mm, which were simulations of material defected. All samples were made in areas where maximum steam temperatures were operating. Welds were tested with destructive and non-destructive methods to determine their quality and define non-compliances detected. The L21HMF cast steel was subjected to a revitalization process, which consisted the hull in subjecting heat treatment in order to obtain favourable structural changes and improve the strength properties. Non-destructive examinations and hardness tests were carried out on the remedial weld, indicating the required quality of repairing remedial weld. Comparative study is aimed at demonstrating the main welding problems during the repair welding of exploitation steam turbine hulls.

Experimental study on generalized constitutive model of hull structural plate with multi-parameter pitting corrosion

Pitting corrosion occurs on the surface of a steel hull structural plate may cause a significant degradation on structural performance. The influence of multiple pitting corrosion-related parameters on the properties of the commonly-used the NV-D36 hull structural plate is experimentally investigated through a uniaxial tension test in which the shape, diameter, depth and distribution form of pitting craters are taken into account. On the basis of the test results, the relations between the degree of pitting (DOP) damage and the properties, i.e. elasticity modulus, yield strength, ultimate strength and peak tensile strain, are studied. As the output of the test, a bilinear and a linear-exponential generalized constitutive models for the NV-D36 hull structural plates considering the multiple pitting corrosion-related parameters are proposed for the design and analytical purposes, respectively. The experimental investigation indicates that all the properties of the NV-D36 hull structural plate degrade linearly but at different rates as the degree of pitting damage increases. The efficient bilinear generalized constitutive model is proved to be acceptable for reserving a reasonable degree of margin. The linear-exponential generalized constitutive model can result in more accurate predictions about the uniaxial tensile response of the NV-D36 hull structural plate experiencing multi-parameter pitting corrosion.

К ВОПРОСУ ОБ ОРГАНИЗАЦИИ НАТУРНЫХ ИССЛЕДОВАНИЙ ПОЛЕЙ БЛУЖДАЮЩИХ ТОКОВ НА МОРСКИХ СУДАХ

When ships are anchored in harbor, corrosion can develop more intensively than at sea, thus, long anchoring can provide corrosion, damage and sinking of the ships. Hence, it is necessary to actively combat corrosion. To increase the efficiency of anticorrosive activity it is necessary to organize operating control of dominating factors of marine environment influencing corrosion of the ship hulls. These factors are: biocorrosion activity of marine environment; physical and chemical characteristics of water (temperature, salinity, pH, oxygen concentration; stray currents in water areas. The ship crews are obliged to control the protection of the hull against electrocorrosion. The article considers one of possible approaches to solving this problem: using a simplified method of control of stray ac thickness, which is based on application of a cheap portable device for measuring current (multimeter) and a portable electrode made of a brush for electric machines. There are shown the results of field experiments indicating that the offered technique to control the protection of steel hull from electrocorrosion allows crew to measure the controlled parameter (intensity of alternating stray current) adequately. The technique helps to estimate protection of the ship’s hull from electrocorrosion under different conditions of mooring and to recommend a berth place for a ship. These results can be used to assess the performance quality of coastal electrical services. The offered technique can be used when developing the automated control system to protect the ship’s hull from electrocorrosion in lasting standstill.

К ВОПРОСУ О ПРОДОЛЖИТЕЛЬНОСТИ ПЕРИОДА ЭФФЕКТИВНОЙ РАБОТЫ СИСТЕМ ЗАЩИТЫ ОТ КОРРОЗИИ СТАЛЬНЫХ КОРПУСОВ ВСПОМОГАТЕЛЬНЫХ СУДОВ

The main protection systems against corrosion of steel hull are lacquer coating and protective action (PA). The running regime control of these systems must be performed by the crew. Nevertheless, Kamchatka fleet crews don’t perform the control alluded to rated resources for lacquer coating (2 years) and for PA (2 years). It has been found that everyday control of protection system is necessary against corrosion of vessel hull if the service vessels run in coastal waters of Kamchatka during winter. The authors have proposed the means of control which effectiveness was proved on a service vessel of Kamchatka fleet. The crew and the ship-owner opportunely got information about protection system modification in state of nonoperability. This permitted organizing maintenance of vessel hull in proper time and cutting down maintenance expenses and reducing repair period by 8-10 times.