Classification Society Rules Research Articles

Оценка критериев параметров вибрации судовых 4-х тактных двигателей на основе правил классификационных обществ

В работе выполнен анализ нормативных документов классификационных обществ по контролю параметров вибрации судовых 4-х тактных двигателей в эксплуатации. Достоинством контроля состояния по сигналам вибрации является не только возможность получения информации о предполагаемом отказе машины к определенному моменту времени и планирования мер по предотвращению этого отказа. В основу анализа входило рассмотрение критериев оценки параметров вибрации и их уровней, для контроля и диагностики выявления неисправностей двигателей, связанных с повышенной вибрацией. В методику экспериментального исследования входило рассмотрение влияния воздействия действующих сил, а также описаны резонансные колебания при изменении частот вращения современных двигателей. Рассмотренные научные труды и опыт авторов, доказывают о необходимости корректировки уровней и мест контроля вибрации на существующих современных двигателей, установленных на различных видах опор и условий эксплуатации. Выполненные исследования позволили объединить и сгруппировать критерии вибрации с учетом рекомендаций заводов изготовителей по контролю и выявить основные диагностические признаки для выявления причин повышенной вибрации двигателей. Проводимые исследования судовых энергетических установок, на основе применения безразборных методов диагностики морских судов в эксплуатации, лежат в основе системы управления автономных судов. The paper analyzes the regulatory documents of classification societies for the control of vibration parameters of marine 4-stroke engines in operation. The advantage of monitoring the condition by vibration signals is not only the possibility of obtaining information about the expected failure of the machine by a certain point in time and planning measures to prevent this failure. The analysis was based on the consideration of criteria for evaluating vibration parameters and their levels, for monitoring and diagnosing engine malfunctions associated with increased vibration. The methodology of the experimental study included consideration of the influence of the action of acting forces, and also described resonant oscillations when changing the rotational speeds of modern engines. The reviewed scientific works and the experience of the authors prove the need to adjust the levels and places of vibration control on existing modern engines installed on various types of supports and operating conditions. The performed studies made it possible to combine and group vibration criteria taking into account the recommendations of manufacturers for control and to identify the main diagnostic signs to identify the causes of increased vibration of engines. The ongoing research of marine power plants, based on the use of non-selective methods of diagnostics of marine vessels in operation, are the basis of the control system of autonomous vessels.

Экономическая эффективность применения систем мониторинга крутильных колебаний на судах

A torsional vibration monitoring system is being investigated, and an assessment of the economic efficiency of its implementation on ships is made. A schematic diagram of the torsional vibration monitoring system is illustrated and a photograph of an experimental sample of the monitoring system is provided. An assessment of the economic efficiency of the implementation of torsional vibration monitoring systems on ships is being carried out to prevent the occurrence of emergency situations with marine propulsion systems. The rules of classification societies, scientific and technical literature in the field of torsional oscillations and industrial economics, and the authors' own research were used as materials. The methods used are analysis and computational experiment. Data on the economic costs of the shipowner in the event of emergency situations in case of fatigue failures of elements of ship's engine and propulsion systems were obtained. An assessment of the costs for the development, installation and maintenance of a torsional vibration monitoring system on ships was made; as well as an approximate assessment of the volume of the Russian domestic market for installation and maintenance of torsional vibration monitoring systems on ships. It is noted that the cost of the consequences of propeller shaft failures ranges from several million to tens of millions of rubles. It is concluded that the development and implementation of torsional vibration monitoring systems will reduce the cost of the shipowner for a routine assessment of the technical condition of torsional vibration dampers and reduce the risks of costly accidents with shipboard engine complexes.

Разработка цифрового двойника демпфера крутильных колебаний судового дизеля при помощи системы мониторинга

The torsional vibration damper of a marine diesel engine is investigated in connection with the development of a digital double of the damper. The development of a digital twin of the torsional vibration damper of a marine diesel engine is carried out using data received from the monitoring system. The rules of classification societies, scientific and technical literature in the field of torsional vibrations and the authors' own research were used. A structural model of the digital twin was obtained with the testing of its functionality on the damper of the torsional oscillations of the main engine MAN B&W 8L27/38 of the vessel of the Turcas project. Conclusions are drawn about the possibility of developing a digital twin of the torsional vibration damper of marine diesel engines and using it to assess the technical condition and purpose of the residual life of the damper. The use of a digital twin made it possible to assess the degree of change in the technical condition and residual life for the torsional vibration damper of the main engine of the MAN B&W 8L27/38 vessel of the Turcas project. As a result of monitoring of the cruise oscillations for the engine-propulsion complex of the tanker of the Turcas project, a definition (assessment) of the technical condition of the damper was given. The assigned resource based on the results of measurements for 11 days is 7 500 hours of work.

A method for improving the hydrostatic pressure testing of the compressive strength of solid buoyancy materials used at full ocean depth

The current optimized synthesis methods for solid buoyancy materials used in manned submersibles at full ocean depth fail to meet the safety factor requirement of 1.5 specified in China Classification Society rules. To address this issue, this study proposes a novel method for enhancing the compressive strength and safety margin of such materials using hydrostatic pressure to screen hollow glass microspheres and eliminate those with low compressive strength. The as-prepared solid buoyancy material is free of surface cracks and has a water absorption rate of <0.1% after a 24-h hydrostatic pressure test at 175 MPa, satisfying the required safety performance standards for buoyancy materials used at full ocean depth. This study highlights the feasibility of using hydrostatic pressure testing to enhance the compressive strength and safety of solid buoyancy materials for full-ocean-depth applications, paving the way for the development of more advanced and reliable buoyancy materials for deep-sea exploration.

Intact stability operational measures: Criteria, standards and examples

Harmonised treatment of design and operation is very efficient to provide a required safety level. However, operation is usually not addressed by intact stability rules of IMO or classification societies. A substantial change was introduced in the second-generation intact stability criteria of IMO, which address both design requirements and ship-specific operational measures. Moreover, this is done using the same criteria, standards, and safety level, so that operational measures can be used as a loading condition-specific alternative to design assessment. This paper proposes several operational measures, discusses relevant criteria, and defines corresponding acceptance thresholds. Further, it is discussed whether operational measures can always be acceptable as an alternative to the design assessment, when operational measures should be prepared, and how cross-sea and ship propulsion and steering abilities can be addressed. Examples of the proposed operational measures are shown for five ships.

Fatigue Strength of AH36 Thermal Cut Steel Edges at Sub-Zero Temperatures

Cruise ships or yachts that operate in areas with seasonal freezing temperatures have large openings in the outer shell. Those are thermal cut edges, and they are exposed to very low temperatures. From fatigue crack growth testing of base materials, it is known that low temperatures can accelerate the crack growth, which may reduce the fatigue life of a structure. However, the current guidelines and rules of classification societies do not provide design curves for the fatigue assessment of thermal cut steel edges at sub-zero temperatures. Therefore, fatigue tests of thermal cut edges are conducted at −20 ∘C and −50 ∘C as well as at room temperatures for reference. The specimens are plasma-cut and tested in a temperature chamber under uniaxial loading with a resonant testing machine. The test results are statistically evaluated using linear regression and the maximum likelihood method. The results show that the fatigue strength at sub-zero temperatures is significantly higher compared to room temperature. The test results of this study indicate that sub-zero temperatures down to −50 ∘C do not seem to cause a reduced fatigue life of thermal cut steel edges.

Tensile Response of Fibre-Reinforced Plastics Produced by Additive Manufacturing for Marine Applications

The present study makes a consistent attempt to evaluate promising additive manufacturing (AM) processes and materials for marine structural applications, paving the way for the development of additively manufactured light-weight composites. The main objective is to analyse the structural performances of fibre-reinforced plastics (FRP) produced by AM for marine applications. In particular, the tensile response of chopped and continuous carbon-fibre-reinforced thermoplastics have been investigated through destructive and non-destructive testing, considering the influence of AM process settings and thermal post-manufacturing treatments. The results demonstrate that continuous fibre-reinforced thermoplastics produced by AM are potentially suited to marine structural applications, since their tensile capacity is superior to the minimum imposed by the Classification Society Rules. However, the mechanical properties of additively manufactured FRP are currently lower than conventional composites. The continuous carbon fibre reinforcement is far more effective than the chopped one, and the additive manufacturing deposition pattern significantly influences the structural capacity. The annealing post-manufacturing treatment enhances the mechanical properties by approximately 10%, decreasing material ductility and manufacturing defects.

Finite Element Simulations of Novel Submersible Design Based on the ASME Design-by-Analysis Approach

Tourist submersibles are a new class of underwater vehicles where new materials and innovative structural concepts are used. Because of the lack of experience with these innovative vessels, prescribed rules of classification societies are not directly applicable in their structural design. Thus, a novel design-by-analysis approach, as given in the Boiler and Pressure Vessel Code of ASME, is employed for dimensioning structural components. Design-by-analysis stands for a consistent set of loads, boundary conditions, modelling principles, failure modes, and safety factors if the finite element analysis is performed instead of using rule formulas. The approach has been used until now in the structural design and optimization of unconventional pressure vessels, while in this paper it is for the first time employed in structural design of the underwater vehicle. This study can serve as guidance for future applications of design-by-analysis in the development of the innovative structures exposed predominantly to the pressure loading.

Analysing Ancient (Viking) Longship Structures

The Nordic longships of the 9th to 11th Centuries were perhaps the preeminent fast assault ships of the period. Modern engineering analytical tools have been employed from time to time to investigate their stability, performance and structural characteristics. The latter is perhaps the most challenging, since the physical problem is that of a hydro-elastic body in rough seas, constructed of a material with highly variable mechanical properties, fastened together by rivets, treenails, nails, spikes, lashings and wedges of uncertain joint efficiency. The corresponding analysis is potentially considerably more complex than the ‘linked-chain’ method commonly employed in modern design offices to establish acceptable scantlings, i.e. classification society rule loads and criteria together with reliable published material property data which are the essential inputs to scantling formulae/finite element analyses (FEA). This paper outlines one small craft naval architect’s view of the issues involved in applying the standard structural design method to the analysis of a ship type which is radically different from modern craft and in so doing identify issues which may be of interest to modern naval architects analysing unconventional lightweight structures.

Relief of Liability for Damages and Strengthening of Korea’s Maritime Trade Through MRA Application of International Classification Association

This study examines the entire process from design, which is the initial stage of construction of ships and oceans, which are responsible for the largest amount of logistics and transportation among types of trade, to final approval, and delivery of maritime trade through final export in various stages of maritime transportation. The purpose of a International Classification Society is to provide classification and statutory services and assistance tothe maritime industry and regulatory bodies as regards maritime safety and pollution prevention, based on the accumulation of maritime knowledge and technology. It is an attestation only that the vessel is in compliance with the Rules that have been developed and published by the Society issuing the classification certificates. In this research, based on the IACS process, which has such ambiguous grounds and standards, the contractual liability for damages was resolved, and Korea’s maritime trade growth and international exports were revitalized by applying the International Classification Association MRA. The contents are summarized as follows. irst, MRA is applied to 1st party Inspection and Declaration, 2nd party Inspection and Testind, and 3rd party Qualification and Certification for Manufacturing Procedure and Process. By applying the MRA (International Mutual Recognition Agreement) process based on the International Classification Society standards and standards to these three types of international classification approval certification and manufacturer certification, the direct cost reduction and It is clear that it will clearly present the s tandards f or e xport approval a nd c ertification t hrough a bsolute t im e reduction, a nd w ill make a great contribution to the development of export manufacturing companies and all industries in Korea. Second, through the application of MRA to Design Assessments of products and services used in maritime trade, the structure of the shipbuilding, offshore and special ship industries is strengthened, and the Korean maritime industry is strengthened by reducing the construction period and direct costs, and maritime trade can be a shortcut to strengthening to be. Third, by applying MRA to the working process of the International Classification Association for export goods and export services that require maritime trade, it is possible to simplify the procedure and reduce the working period and cost. Fourth, by promoting the integration of the classification society rules first and applying MRA, it is possible to eventually promote the integration of international standards. Finally, the application of MRA to international maritime export products and services is a fundamental means of resolving the liability for damages in the essential contract of maritime trade and export.

Importance of Condition Assessment Programme by Ultrasonic Measurement

Paper gathers information on Condition Assessment Programme (CAP), which is implemented by classification societies to thoroughly assess condition of tankers and bulk carriers by inspection of engine and hull. It is voluntary programme, mostly participated by tankers and bulk carriers which are fifteen and more years old and today less present on the market. Special focus will be on ultrasonic measurement of thickness of ship´s plates which is most significant indicator on condition of older vessels. After all measuring is done, data is compared with classification society rules and condition of hull and machinery will be assessed. This kind of inspection provides owners of older ships proof that despite age their ships are equally capable of conducting sea voyage. The authors analyse the number of ship arrivals in the port of Rijeka to gain a better insight into their age. Furthermore, the authors advocate ultrasonic thickness measurement for the purpose of reducing hazards.

Fatigue Estimation on a High-Speed Wave Piercing Catamaran During Normal Operations

The estimation of fatigue life in the design process is particularly important for weight-optimised ships such as high-speed aluminium craft, but to date no research has been published on the fatigue accumulation on large wave-piercing catamarans, focusing on long-term operations. This paper assesses the applicability of classification society rules for high-speed catamarans with respect to fatigue design. This was achieved by comparing the long-term distributions of stress, measured on a 111m long wave-piercing catamaran ferry whilst operating in the Canary Islands and during the delivery voyage, with load spectra estimated using a method accepted by the classification society, DNV. The paper also proposes an improved distribution fitment method for fatigue analysis. A detailed method to convert measured stress histories in the time domain into an appropriate stress-spectrum and fitment of Weibull parameters is presented. Results show that the simplified method accepted by the classification society is highly conservative regarding fatigue estimation compared to fatigue results based on measured data. The proposed combined Weibull fitment method substantially improves the accuracy of simplified fatigue analysis methods.

Design and finite element analysis of gondola construction for multibeam echosounder (MBES) installation on RV Baruna Jaya III - BPPT

The revitalization of hydrographic equipment at the Research Vessel (RV) Baruna Jaya III has been carried out by the Technology Center for Marine Survey (BTSK) – BPPT to improve its service capabilities. A Multi-Beam Echosounder (MBES) for the deep-sea mapping up to 8000 meters depth has been chosen to replace the existing equipment which only has a mapping capability of 3000 meters depth. MBES requires a support construction mounted on the vessel hulls as its housing, considering the installation principle from both the shipowner and MBES maker. In this research, a gondola installation principle has been agreed to develop. The gondola construction has been designed in consideration of actual vessel conditions and several requirements by the MBES maker. The design construction is further analyzed using the finite element method (FEM) to ensure its strength and safety and meet Indonesian Classification Society (BKI) minimum requirements. The analysis conditions are divided into 3; hydrostatic load (A), sensors load (B), and the combination of hydrostatic and sensor load (C). The von Mises stress was obtained from finite element analysis for conditions A, B, and C, respectively, 164 MPa, 1.552 MPa, and 160.8 MPa. The analysis results in all loading conditions have met the minimum allowable stress required by Indonesia Classification Society rules, which is 180 MPa. In conclusion, the design of the gondola construction for MBES installation on RV Baruna Jaya III has good structural strength and safety, so it is feasible to use.

Parametric study of bow slamming for a KRISO container ship

A systematic parametric study is performed in the present work to investigate the influence of various physical and geometrical parameters, such as wave steepness, wavelength, vessel speed, relative velocity on bow slamming load. For this purpose, a CFD-based one way coupled method is used. The ship's heave and pitch motions are determined using a standard potential theory-based method. Subsequently, the estimated values are used as input to a finite volume-based commercial CFD solver for computing slamming pressure. A scaled KRISO container ship (KCS) model is chosen for the analysis. Initially, the present numerical model is compared with state-of-the-art numerical and theoretical results to establish the correctness of the proposed model. A series of cases is then taken to check the dependency of bow slamming pressure on various physical and geometric parameters. In the final part of the paper, an empirical formula is developed based on this parametric study and with the help of the curve fitting method. It is observed that the developed analytical formulation corroborates well with CFD results and classification society rules and can be used for the quick prediction of bow slamming pressure for estimating design slamming load.

Propeller Load Modelling In The Calculations Of Marine Shafting Torsional Vibrations

Technical rules of IACS classification societies require that calculations of torsional vibrations for all propulsion shafting systems, as well as for shafting systems of auxiliary machinery above certain power, shall be prepared, submitted and validated for the vessels requesting the class certificate. These calculations may be approached either by conventional analytical models based upon systems of ordinary differential equations describing the actual dynamic system, or by simulation modelling of the same dynamic system. The research team of the authors has been established within the R&amp;D Centre of the Faculty of Maritime Studies at Split. The aim of the team is to investigate possibilities and constraints for implementation of the SimulationX software to the simulation modelling of torsional vibrations of dynamic systems, such as marine propulsion and auxiliary shafting. In general, results of these calculations depend upon the concept of the system (two-stroke vs. four-stroke Diesel engine, torsional vibration damper present or not, flexible coupling present or not, fixed pitch or controllable pitch propeller, etc.), dimensions of components, their material properties and service loading. Propeller load modelling within the service loading is very important. Even the preliminary research results show that its simplest part, i.e. the steady-state propeller loading of the system without taking excitations into account, may have a significant influence on the results of torsional vibrations calculation and consequently even to their acceptability by the class society. For this reason, the present paper describes two different ways to express propeller steady-state loading formulations, as prescribed by different sources and authorities, as well as their influence on the torsional vibrations calculation results and meeting the criteria of the IACS Unified Requirements, presenting them in a real verified and validated case study.

An Overview of the Ship Ventilation Systems and Measures to Avoid the Spread of Diseases

This article presents a review of the main aspects regarding the current rules of classification societies, standards, and practice regarding the design and construction of ventilation and air conditioning systems for different compartments in different types of ships. In the context of the COVID-19 pandemic, this paper also presents the usual practice of the actual heating ventilation and air conditioning (HVAC) systems used on large ships, which recirculate the air between living compartments, in comparison with the new requirements to avoid the risk of spreading diseases. According to the rules, the technical compartments are provided with independent ventilation systems that ensure high air flow rates; therefore, the spread of diseases through this system is not an issue. The living spaces are provided with common ventilation and air conditioning systems that recirculate the air in all compartments served. The current practice of air recirculation in various living rooms leads to the spread of diseases, which should therefore be analyzed and improved by adding high-efficiency particulate air (HEPA) filters and UV disinfection or be replaced with individual systems that provide local heating or cooling without air recirculation between different rooms and fresh air supply with complete evacuation. For existing ships, different solutions should be analyzed such as reducing or cancelling recirculation and increasing filtration.

Application of Large Eddy Simulation to Predict Underwater Noise of Marine Propulsors. Part 2: Noise Generation

Methods to predict underwater acoustics are gaining increased significance, as the propulsion industry is required to confirm noise spectrum limits, for instance in compliance with classification society rules. Propeller–ship interaction is a main contributing factor to the underwater noise emissions by a vessel, demanding improved methods for both hydrodynamic and high-quality noise prediction. Implicit large eddy simulation applying volume-of-fluid phase modeling with the Schnerr-Sauer cavitation model is confirmed to be a capable tool for propeller cavitation simulation in part 1. In this part, the near field sound pressure of the hydrodynamic solution of the finite volume method is examined. The sound level spectra for free-running propeller test cases and pressure pulses on the hull for propellers under behind ship conditions are compared with the experimental measurements. For a propeller-free running case with priory mesh refinement in regions of high vorticity to improve the tip vortex cavity representation, good agreement is reached with respect to the spectral signature. For behind ship cases without additional refinements, partial agreement was achieved for the incompressible hull pressure fluctuations. Thus, meshing strategies require improvements for this approach to be widely applicable in an industrial environment, especially for non-uniform propeller inflow.

Proposed Design Criteria for a Bilge Pumping System for Large Container Ships

The IMO’s Goal-Based Standards (GBS) in the Safety of Life at Sea Convention (SOLAS) sets the high-level goals (GBS Tier 1 and 2) and classification societies acting as recognized organizations (ROs) should develop detailed rules and regulations in order to meet the goals (GBS Tier 4). Even though the GBS requirements are applicable to new build construction standards of bulk carriers and oil tankers at present, given that IMO may develop goal-based standards for other safety areas, it will be meaningful to examine the bilge pumping system requirements in the context of principles of Goal-Based Standards. The bilge pumping system is one of the most important systems in ships but there is no requirement for its performance except for the 2 m/s speed of water requirement and the internal diameter of bilge main prescribed in SOLAS. The purpose of this study is to quantitatively evaluate bilge pumping performance of actual ships in service and to propose an alternative set of performance standards. The rules of Classification Societies were investigated, and the bilge pumping performance was quantitatively evaluated using specifications of a 14,000 TEU class container ship. As a result of the investigation, it was found that satisfying the 2 m/s requirement under many operating conditions was impossible, and the rules and regulations to determine the internal diameter of bilge main and the capacity of bilge pump did not meet intended purpose of the 2 m/s speed of water requirement. Finally, a set of design criteria are proposed to fulfil the intended purpose of the 2 m/s requirement of SOLAS.

Diagrams of static stability of a ship in rough conditions

Static stability diagram, solid-state model of a ship when constructing a static diagram of a ship in accordance with the requirements Of the rules of classification societies, it is necessary to take into account special navigation conditions: icing, the presence of liquid cargo in tanks, etc. In this case, the presence of the ship's side pitching caused by the action of waves is taken into account only at the time of determining the restoring moments. This article analyzes the influence on the stability diagram of the shape of the water surface (wave profile) on which the inclination occurs. Building a complex form of volume displacement, caused not only by the form of a surface ship, but a change in waterline, made with the use of solid modeling theoretical hull and volume of the water pool in the environment of Autodesk AutoCAD and Visual Lisp. For test calculations, it is found that the possible deviation of the static stability arm and the area under the positive part of the diagram can reach twelve percent.

Influence of corrosive wear on hull strength of sea-going ships

Object and purpose of research. This paper discusses hulls of ships, both in-service and under construction. The purpose of the research is to evaluate and monitor the effect of corrosion wear on their global and local strength.&#x0D; Materials and methods. Corrosion wear was taken into account on the basis of the methodology of the Rules of the Russian Maritime Register of Shipping and service life test data for hull samples. The assessment of the corrosive wear effect on the local strength of the plates was carried out using the finite element method.&#x0D; Main results. The corrosive wear effect on the parameters of global and local strength of ship hulls is considered. Experimental fatigue curves are obtained from service-life test results for welded samples with and without corrosive wear. Numerical modeling of the change in the stress-strain state of the plate on the size and number of corrosion pits is performed. Various methods of accounting for corrosive wear in the rules of international and indigenous classification societies are considered.&#x0D; Conclusion. The obtained results demonstrate and confirm the need to take into account corrosive wear when calculating the overall and local strength of new and used ship hulls.