Tanker Safety Research Articles

Consequences of the Improved Wave Statistics on a Hull Girder Reliability of Double Hull Oil Tankers

This paper investigates the change in hull girder failure probabilities and partial safety factors caused by the implementation of the new procedure for direct computation of wave loads recommended by the International Association of Classification Societies (IACS). Differences between new and previous procedures are primarily related to the different associated scatter diagrams, and secondarily due to the assumptions on wave spectrum, wave energy spreading, and ship speed. This study performs a comparative structural reliability analysis of the global longitudinal bending of five oil tankers of different sizes between two procedures for wave load computation. Firstly, failure probabilities are compared, and secondly, modified partial safety factors are proposed, resulting in similar failure probabilities according to two separate procedures. It is found that implementation of the new revision of the IACS procedure for direct computation of wave loads results in a reduction of the minimum required ultimate vertical bending capacity of a ship hull by 10%. In addition to the novel investigation of the safety of oil tankers using a revised wave scatter diagram, this study offers a new rapid method for calculation of extreme vertical wave bending moments based on the regression of the parameters of the Weibull function, used for the long-term probability distribution of wave-induced loads.

Analyzing human reliability for the operation of cargo oil pump using fuzzy CREAM extended Bayesian Network (BN)

Crude oil cargo discharging operations can be performed by cargo oil pumps in tanker ships. Considering the harmful effects of crude oil, any failure during the cargo oil pump operation may pose acute hazards such as temperature and pressure increase in pipelines, leakage, fire, and following undesired events that lead to marine environmental pollution and toxic effects to humans. The process is managed by the ship's crew, and it requires following the operational steps in order. This paper aims at performing a detailed human reliability analysis (HRA) for the operational process of cargo oil pumps on a tanker ship. In the paper, the Cognitive Reliability and Error Analysis Method (CREAM) is used to calculate human error probability under a fuzzy set which deals with the uncertainty and ambiguity of the CPC (Common Performance Condition). The Bayesian Network (BN) approach is adopted to determine the probability distribution of the control modes in reliability assessment. In view of the findings, the human reliability for the entire process of cargo oil pump operation on tanker ship is found 8.82E-01. The outcomes of the paper provide valuable insight into the improvement of tanker safety in shipboard operation and performance reliability assessment.

PSYCHOLOGICAL ANALYSIS OF ENVIRONMENTAL FACTORS OF OIL SPILL IN SHENZHEN PORT

PSYCHOLOGICAL ANALYSIS OF ENVIRONMENTAL FACTORS OF OIL SPILL IN SHENZHEN PORT

Study on the critical factors and hot spots of crude oil tanker accidents

The safety of crude oil tankers is always a focus under the rapid development of oil trade and maritime transportation. The purpose of this study is to investigate the critical factors that lead to crew casualties and address the hot spot distribution characteristics by reviewing accident data over the last 26 years. A Zero-Inflated Negative Binomial (ZINB) regression model is introduced to evaluate the extent of eight selected factors on crew mortality. Three others regression models (Poisson, Negative Binomial, and Zero-Inflated Poisson regression model) are chosen for model comparison to demonstrate the superiority of the ZINB model. The results showed that the ZINB model outperforms the other regression models in terms of fitting performance. The leading contributors of the crude oil tanker accident casualties were found as foundered and fire/explosion, followed by war loss/hostilities, collision, weather conditions, classification society, hull/machinery damage, and ship size. Furthermore, the Kernel Density Estimation (KDE) methodology is adopted to identify hot spots and their trend evolution features of critical accident factors. Crude oil tanker accidents were observed more likely to occur in the waters around the United Kingdom, Gulf of Mexico, Strait of Malacca & Singapore Strait, Mediterranean Sea, China, Japan & Korea, and the Gulf Area, which may be due to the dense shipping routes, poor geographical conditions, and adverse weather conditions. The results of this study provide conducive suggestions for those policy-makers to develop appropriate and effective strategies for preventing crude oil tanker accidents.

Using Structural Topic Modeling to Explore the Role of Framing in Shaping the Debate on Liquefied Natural Gas Terminals in Oregon

The drastic increase in domestic production of natural gas due to the fracking boom prompted efforts to develop a robust infrastructure in the U.S. to export natural gas. Given environmental concerns over increased fossil fuel development, significant opposition mobilized to “keep it [fossil fuels] in the ground” by acting to prevent not only natural gas production but also its transportation via pipelines and shipping via export terminals. Our analysis focuses on the latter component, specifically examining the long history of proposed liquefied natural gas infrastructure in two coastal communities in Oregon. Members of the public engaged in the formal siting processes and mobilized both opposition and support. We examine their use of collective action frames in both comments at public hearings and letters to the editor in local newspapers ( N = 4618) over the 16 years that these proposals were under consideration, quantifying the dynamic nature of framing using computational text analysis. We find that both groups vary their use of framing over time and by venue, reacting to exogenous events (e.g., September 11th, Fukushima) and tailor their messages to the context (e.g., an in-person hearing or a letter to the editor). Opponents concentrated on potential threats, initially emphasizing local impacts like tanker and pipeline safety but eventually focusing on climate concerns. Supporters, meanwhile, stressed the economic benefits of the projects but alternated their specific framing based on venue—focusing on employment when talking to regulatory agencies and community economic benefits in letters. While this juxtaposition of economic benefits and environmental threats was a key part of public discourse, opponents also expanded their framing to questions of local sovereignty and governance, allowing a broader coalition to develop and ultimately succeeding in defeating the proposals.

Quantitative failure analysis for static electricity-related explosion and fire accidents on tanker vessels under fuzzy bow-tie CREAM approach

Cargo operations on tanker vessels involve high risks to crew and the marine environment. At the time of loading and unloading of cargoes and tank cleaning operations, consequences of accidents may be severe such as loss of lives, property loss and marine pollution. One of the most critical accidents is an explosion which may advance to a large fire. An explosion may occur due to flammable and combustible materials, electric arcs, dangerous operations, like hot work on deck, or static electricity. This study focuses on the issue of static electricity, which is one of the serious threats onboard and can cause large explosions under hazardous conditions if a discharge is in contact with nearby flammable gases or air mixture. In a bow-tie structure, static electricity-related explosion and fire accident was determined as the top event. In the fault tree diagram, intermediate events were considered as the flammable atmosphere in a tank, operational failures, technical failures, and unsafe practices which cover direct human errors. Fuzzy logic and Cognitive Reliability and Error Analysis Method (CREAM) were used for quantitative failure analysis, and the probability of accident risk was found as 6.31E-02. Findings show that the most critical contributions to the top event are minimal cut sets of lack of monitoring cargo tank atmosphere, inadequate actions for reducing the O2 level in tank, failure to understand safety data sheets, failure to follow procedures, non-bonded ullage & sample apparatus. The research provides a significant contribution to the literature and gives information regarding static electricity risks to ship officers, tanker safety superintendents and other maritime authorities to improve the safety of cargo operations.

Application of fuzzy bow-tie risk analysis to maritime transportation: The case of ship collision during the STS operation

Risk analysis is of paramount importance in maritime transportation due to the particularly hazardous nature of the work. While the International Maritime Organization (IMO) has circulated Formal Safety Assessment (FSA) for the assessment of on-board risk, it has not introduced a specific tool for risk analysis, and a more proactive approach to the assessment of risk is consequently sought by maritime safety researchers. This paper aims to demonstrate how the fuzzy bow-tie method of analysis might be deployed to quantitatively analyse risk. Focussing on the specific context of ship to ship (STS) cargo operations enables specific insights into the method to be gained. The findings of the research can be utilised by maritime safety professionals (STS superintends, mooring masters, tanker safety inspectors, company fleet managers, and tanker shipowners) in order to mitigate potential risks and enhance marine safety during the STS operation.

Earth Observation and Artificial Intelligence for Improving Safety to Navigation in Canada Low-Impact Shipping Corridors

In 2014, through the World-Class Tanker Safety System (WCTSS) initiative, the Government of Canada launched the Northern Marine Transportation Corridors (NMTC) concept. The corridors were created as a strategic framework to guide Federal investments in marine transportation in the Arctic. With new government investment, under the Oceans Protection Plan (OPP), the corridors initiative, known as the Northern Low-Impact Shipping Corridors, will continue to be developed. Since 2016, the Canadian Hydrographic Service (CHS) has been using the corridors as a key layer in a geographic information system (GIS) model known as the CHS Priority Planning Tool (CPPT). The CPPT helps CHS prioritize its survey and charting efforts in Canada’s key traffic areas. Even with these latest efforts, important gaps in the surveys still need to be filled in order to cover the Canadian waterways. To help further develop the safety to navigation and improve survey mission planning, CHS has also been exploring new technologies within remote sensing. Under the Government Related Initiatives Program (GRIP) of the Canadian Space Agency (CSA), CHS has been investigating the potential use of Earth observation (EO) data to identify potential hazards to navigation that are not currently charted on CHS products. Through visual interpretation of satellite imagery, and automatic detection using artificial intelligence (AI), CHS identified several potential hazards to navigation that had previously gone uncharted. As a result, five notices to mariners (NTMs) were issued and the corresponding updates were applied to the charts. In this study, two AI approaches are explored using deep learning and machine learning techniques: the convolution neural network (CNN) and random forest (RF) classification. The study investigates the effectiveness of the two models in identifying shoals in Sentinel-2 and WorldView-2 satellite imagery. The results show that both CNN and RF models can detect shoals with accuracies ranging between 79 and 94% over two study sites; however, WorldView-2 images deliver results with higher accuracy and lower omission errors. The high processing times of using high-resolution imagery and training a deep learning model may not be necessary in order to quickly scan images for shoals; but training a CNN model with a large training set may lead to faster processing times without the need to train individual images.

Oil tanker risks on the marine environment: An empirical study and policy implications

Oil pollution, which is mainly caused by oil tanker accidents, is an important concern in the protection of the marine environment. In order to propose pollution prevention policy for oil tankers, this study first employs four machine learning methods to evaluate oil tanker accident probability, and then proposes a risk evaluation system which is jointly measured by accident probabilities and consequences. Crude oil tanker accident data from 1991 to 2016 were collected and analyzed. The main findings are as follows: First, the random forest (RF) method produces the best overall performance for oil tanker accident probability. Second, the accident probabilities of larger crude oil tankers are lower, while older vessels within the parameter of 0–15 years exhibit declining accident probabilities. Third, tankers classified by the International Association of Classification Societies (IACS) members, registered in closed registry, built in China and South Korea, or owned by developed countries prove to be safer with lower accident probabilities. Fourth, the use of double hull in tankers also contributes to a higher tanker safety level. The results contribute to marine environment protection by helping stakeholders to identify accident risk factors, assess accident risk and take actions to reduce accident probabilities.

A quantitative risk analysis by using interval type-2 fuzzy FMEA approach: the case of oil spill

ABSTRACTRisk assessment in maritime domain is one of the most cited topics since maritime transportation poses potential hazard for human life, marine environment and property. To mitigate risk and enhance safety awareness in maritime transportation, safety researchers have been seeking proactive solutions. This article prompts a quantitative risk-based approach combining interval type-2 fuzzy sets (IT2FSs) with failure mode and effect analysis (FMEA) to perform a comprehensive risk analysis. Thus, potential failure modes and their effects are revealed by calculating risk prioritisation numbers (RPNs). Whilst the FMEA method provides a robust risk analysing tool with relevant control options, the IT2FSs deals with ambiguity and vagueness of linguistic assessment of decision-makers through the FMEA. Hence, expert’s linguistic assessment in risk assessment can be transformed into useful information in terms of enhancing safety and pollution prevention in maritime industry. To demonstrate the proposed approach, potential failures and effects of a real shipboard oil spill case are handled. The findings show that incomplete information exchanged with local maritime authorities, malfunction of oil skimmer and poor organization of shoreline clean-up team are the most important failures during case of oil spill. The proposed approach provides not only theoretical insight into the maritime transportation industry but also practical contributions to chemical/oil tanker safety and environmental protection by mitigating risk in terms of technical or operational aspects.

Inspections on Board Oil Tankers

Oil tanker inspections have an important role in enhancing safety and minimizing the risk of oil pollution. However, research has indicated that inspection items are overlapping among inspection regimes observed in a given time span on board oil tankers, thus making negative impact on ship safety, unnecessarily consuming shipboard human resources and having adverse economic effects. In this paper, current inspections performed on board oil tankers have been presented, including duration, intensity and average costs, directly or indirectly paid by shipowners. Our analysis of surveyed components by all regimes has showed that it is possible to reduce critical inspection parameters without compromising safety by introducing a unified inspection method. A content of such inspection, consisting of 529 components, has been presented. Performing the proposed inspection method and sharing its results among interested parties of oil tanker safety regime has been suggested as a measure that could improve oil tanker safety and pollution prevention.

Northern marine transportation corridors: Creation and analysis of northern marine traffic routes in Canadian waters

AbstractThe concept of the Northern Marine Transportation Corridors (NMTC) initiative was developed under the Government of Canada World‐Class Tanker Safety System Initiative (WCTSS). The NMTC is an interdepartmental Arctic initiative within the Department of Fisheries and Oceans Canada (DFO), through the Canadian Coast Guard (CCG) and the Canadian Hydrographic Service (CHS), in collaboration with Transport Canada (TC). The NMTC initiative was developed to strengthen the safety of marine navigation in the Arctic, and to offer an efficient planning guide for present and future Arctic investments. Transportation corridors identified through this initiative will provide the Government of Canada the framework needed to better prioritize and deliver on its programs and services, including: nautical charts and products; aids to navigation; icebreaking services; and marine safety regulations. The corridors were generated and analyzed with a Geographic Information System (GIS) using two main data sources: the Automated Identification System (AIS) and CHS's nautical charts and publications. The geographic extent of the NMTC is defined as the Northern Canada Vessel Traffic Service Zone (NORDREG Zone) and the Mackenzie River. With close to 4 million km2 of water in the Arctic and 162,000 km of coastline, surveying the Arctic to modern standards represents an enormous challenge to CHS. By adopting a corridor‐based approach, CHS and other government programs can prioritize their efforts on 12% of the Canadian Arctic waters. CHS currently has 32% of the NMTC adequately surveyed, with an additional 3% surveyed to modern standards.

Electromagnetic backscattering from one-dimensional drifting fractal sea surface II: Electromagnetic backscattering model**Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, the Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian

Sea surface current has a significant influence on electromagnetic (EM) backscattering signals and may constitute a dominant synthetic aperture radar (SAR) imaging mechanism. An effective EM backscattering model for a one-dimensional drifting fractal sea surface is presented in this paper. This model is used to simulate EM backscattering signals from the drifting sea surface. Numerical results show that ocean currents have a significant influence on EM backscattering signals from the sea surface. The normalized radar cross section (NRCS) discrepancies between the model for a coupled wave-current fractal sea surface and the model for an uncoupled fractal sea surface increase with the increase of incidence angle, as well as with increasing ocean currents. Ocean currents that are parallel to the direction of the wave can weaken the EM backscattering signal intensity, while the EM backscattering signal is intensified by ocean currents propagating oppositely to the wave direction. The model presented in this paper can be used to study the SAR imaging mechanism for a drifting sea surface.

Electromagnetic backscattering from one-dimensional drifting fractal sea surface I: Wave–current coupled model**Project supported by the National Natural Science Foundation of China (Grant No. 41276187), the Global Change Research Program of China (Grant No. 2015CB953901), the Priority Academic Development Program of Jiangsu Higher Education Institutions (PAPD), Program for the Innovation Research and Entrepreneurship Team in Jiangsu Province, China, the Canadian Program

To study the electromagnetic backscattering from a one-dimensional drifting fractal sea surface, a fractal sea surface wave–current model is derived, based on the mechanism of wave–current interactions. The numerical results show the effect of the ocean current on the wave. Wave amplitude decreases, wavelength and kurtosis of wave height increase, spectrum intensity decreases and shifts towards lower frequencies when the current occurs parallel to the direction of the ocean wave. By comparison, wave amplitude increases, wavelength and kurtosis of wave height decrease, spectrum intensity increases and shifts towards higher frequencies if the current is in the opposite direction to the direction of ocean wave. The wave–current interaction effect of the ocean current is much stronger than that of the nonlinear wave–wave interaction. The kurtosis of the nonlinear fractal ocean surface is larger than that of linear fractal ocean surface. The effect of the current on skewness of the probability distribution function is negligible. Therefore, the ocean wave spectrum is notably changed by the surface current and the change should be detectable in the electromagnetic backscattering signal.

Probabilistic oil outflow: the tanker fleet in the context of risk analysis

The study of safety and environmental friendliness of tankers remains a vital concern of the shipping industry, and the analysis of risk regarding oil spillage from this type of ships is considered as a top priority item in the agenda of shipping. In this context, the paper is focused on the implementation and probabilistic formulation of regulation 23 of MAPPOL to calculate distribution and quantities of oil outflow for all major oil tanker categories such as Aframax, Suezmax, VLCC, etc. Dedicated databases for each tanker size category have been developed, checked for statistical acceptance, and utilised to obtain all necessary inputs for the calculation of oil outflow. Subsequently, numerous cargo tank configurations per tanker size were examined (for double hull vessels following regulation 19 of MARPOL), multiple scenarios were drafted, and these were put under simulation exercises to come up with oil outflow probabilistic distributions. The paper concludes with a framework for the assessment of costs for (tanker) oil spills.

An Application of FSA Methodology to the Safety of Bulk Chemical Tankers

Based on detailed analysis of the risk of bulk chemical tanker transportation, a societal risk acceptance criterion is established. The criterion takes advantage of formal safety assessment (FSA) methodology, which is widely used to analyze risk in maritime industry. In the end of this paper, the negligible range, the ALARP range and the intolerable range of bulk chemical tanker in China are estimated in the criterion.

Design of marine structures with improved safety for environment

The paper describes a method for design of marine structures with increased safety for environment, considering also the required investment costs as well as the aspects of risk distribution onto the maritime stakeholders. Practically, the paper seeks to answer what is the optimal amount that should be invested into certain safety measure for any given vessel. Due to the uneven distribution of risk, as well as the differing impact of costs emerging from safety improvements, stakeholders experience conflicting ranking of alternatives. To solve this multi-stakeholder decision-making problem, in which each stakeholder is a decision-maker, the method applies concepts of group decision-making theory, namely the Game Theory. The method fosters axiomatic definition of the optimum solution, arguing that the solution, or the final selected design, should satisfy the non-dominance, efficiency, and fairness. These three are thoroughly discussed in terms of structural design, especially the latter. Considering the coupling of environmental risk and structural design, the method also builds on the preference structure of four maritime stakeholders: yards, owners, oil receivers and the public, who either share the risks or directly influence structural design. Method is presented on a practical study of structural design of a tanker with a crashworthy side structure that is capable of reducing the risk of collision. The outcome of this study outlines a number of possibilities for successful improvement of tanker safety that can benefit, concurrently, all maritime stakeholders.

THE DEVELOPMENT OF A RISK ASSESSMENT MODEL TO COMPARE OIL SPILL RISK FOR SINGLE & DOUBLE HULLED FPSOS

ABSTRACT In recent years, following a number of high profile oil spills internationally, there has been an increased focus on improving the safety of oil tankers to prevent the environmental damage caused by oil spills. Regulations developed focus on replacing single hulled trading tankers with a double hulled configuration. However, many of the risks associated with trading tankers do not apply to Floating Production, Storage and Offloading vessels (FPSOs). The risk assessment undertaken for this report compares single with double hull FPSOs, with respect to events causing serious environmental impact. The study considers external and on-board causes of events which may cause serious oil spills including fire, explosion, accidental discharge, grounding, collision and hull failure. The risk assessment comprises a limited quantitative analysis using data from the literature and observations from experience, which are consistently applied to each of the hazardous events identified as relevant. The report also looks at the wider environmental factors associated with single versus double hull FPSOs in order to inform policy makers. The findings indicate that risk profiles of oil tankers are markedly different from FPSOs, and that there is a strong argument that overall environmental risks from a single hull FPSOs are lower than those for a double hulled F?SO. A single sided hull has potentially better structural performance; no risk of inter-hull formation of volatile explosive mixtures; delivers environmental benefits; and has simpler operational requirements than a double sided FPSO. The main advantage for using a double sided hull is the higher collision impact energy it can withstand without releasing oil into the environment.

Tanker safety: Regulatory change

There are many regulatory changes being imposed on tanker operators of new and existing ships. This paper provides a brief on the main changes and their practical impact on design and operation i.e. the significant recent and upcoming revisions to IMO MARPOL Annexes I, II and VI, SOLAS and other regulations and the IACS Common Structural Rules.

Tanker safety and coastal environment: Prestige, Erika, and what else?

such conditions. Even highly sophisticated ships like the German Neuwerk, which arrived in the area on 25 November, had to wait for more favorable conditions. After the crack of the hull, about 20,000 tons of sticky liquid spilled out onto the sea surface. Within the first week, about 2, 000 tons reached Spanish beaches. The PRESTIGE was carrying about 78,000 tons of heavy fuel oil. Most of the oil is still in the sunken vessel. In the beginning , some scientists estimated that the highly viscous cargo would solidify in the freezing depths and stay in the tanks. However, some weeks later, a submarine identified a steady flow of oil out of cracks, gauging and venting outlets with a volume estimated to be more than 100 tons a day. As the behavior of heavy fuel oil in the marine environment is well known and desribed, the associated risks can be estimated. There will be no decay of the gelatonous oil within the tanks. Such products are characterized as having long-chain hydrocarbons, almost no loss by evaporation, almost no water-soluble fraction, a relatively low bioaccumulation potential, but a high persistence in the environment as tar bals or gel slicks. With its viscosity and density properties, it is a persistent, slicky floater on the sea that will ultimately be washed onto the coast. Oily slick will take on up to 4–5 times water and form a 'mousse'. Depending on density, which will change by the evaporation of fumes, separation of water soluble parts and diverse chemical reactions ('weathering'), the slicky slices could submerge and drift below the surface. Similar behavior is estimated for the gel, that is formed under pressure in the cold deep sea. The properties of heavy fuel oils make them considerably more difficult to skim, pump and clean from equipment than lighter oils. Experiences have shown that the use of crane-operated clamshells, buckets or other mechanical grabbers are most effective. Chemical dispersants do not work well, even in calm weather, and at-sea recovery of widely scattered tar balls is not feasable, while at-sea recovery of oil slicks and emulsions is effective and will not require highly-sophisticated ships (O'Brian 2002). The main problem with heavy fuel oil, however, is that the oil is broken into fragments and spread across an area of thousands of square kilometers, with no evaporation. Contaminated with sand it becomes heavier and could drift back into the sea, to surface at a later point in time. Heavy fuel oils cause cancer by prolonged skin contact, because of the high content of carcinogenic polynuclear aromatic hydrocarbons, PAH (Concave 1998). PAH content has been discussed as one of the reasons for genetic damage, reproductive failure and brain lesions in marine populations after the EXXON 1 The Situation