Hull Tank Research Articles

THE CHALLENGES OF MAJOR TANK COATING REFURBISHMENT PROJECTS FOR ON-STATION FLOATING ASSETS

The objective of this paper is to acknowledge that major tank coating refurbishment projects to FPSO’s and FSU’s are likely to be required during the life of these assets. It highlights the key challenges of achieving these major coating projects in an offshore environment, whilst the assets remain operational and in-production. As these floating assets age the original coatings applied to protect the internal (and external) hull, deteriorate. In an industry with a reluctance for extensive dry-dockings, there is an expectation that any coating refurbishment campaigns can be achieved safely and efficiently whilst the assets remain on-station and in-production, in preference to costly steel renewal’s which may be required at a future date if coatings are not maintained in good condition. With often complex, congested and hazardous topsides processing equipment and pipework directly above the hull tanks, there’s a need for systems, procedures, and specialist equipment to ensure the safety of the personnel entering confined spaces for extended periods. There’s also a need to plan and engineer the works appropriately, using best practice and emergent technologies to improve safety, reduce bedding impacts and to ensure the success of the coating campaign. This paper explores the challenges of major coating projects by discussing the importance of planning and preparation, the need to create a safe working environment within the confined space worksites, the role surface preparation plays in the success of coating projects, and finally the application of coatings and the challenges this operation can present. The key considerations are summarised in 10 specific conclusions as guidance to promote successful project outcomes.

Predicting the residual fatigue life of a cargo hull tank using a deep-learning technique

ABSTRACT Unexpected loads are commonly applied in cargo ships when workers fail to comply with applicable regulations while loading and unloading cargo. This important factor can shorten the design life of a ship by increasing the possibility of structural damage. One way to improve the reliability of the fatigue life of a ship is to check for fatigue damage by observing real-time stress response depending on marine environmental conditions. Modern stress monitoring systems are installed in critical spots to capture stress signals and used to minimize the risk of crack occurrence. In the present study, a hull residual life prediction procedure was introduced by integrating traditional fatigue analysis and the stress response obtained from strain gauges installed in the hull. A three-cargo-hold oil tanker model was used to calculate the residual fatigue life using Harmonized Common Structure Rules (CSR-H). For evaluation, data obtained from the strain gauges and predicted data using a deep-learning technique were compared. According to the results, this process could be applicable to predicting residual fatigue life during a ship’s operation in real time if a long period of statistical data is available. The developed techniques can help analyzing the fatigue integrity of operating ships and ship equipment.

The Challenges of Major Tank Coating Refurbishment Projects for On-Station Floating Assets

The objective of this paper is to acknowledge that major tank coating refurbishment projects to FPSO’s and FSU’s are likely to be required during the life of these assets. It highlights the key challenges of achieving these major coating projects in an offshore environment, whilst the assets remain operational and in-production. As these floating assets age the original coatings applied to protect the internal (and external) hull, deteriorate. In an industry with a reluctance for extensive dry-dockings, there is an expectation that any coating refurbishment campaigns can be achieved safely and efficiently whilst the assets remain on-station and in-production, in preference to costly steel renewal’s which may be required at a future date if coatings are not maintained in good condition. With often complex, congested and hazardous topsides processing equipment and pipework directly above the hull tanks, there’s a need for systems, procedures, and specialist equipment to ensure the safety of the personnel entering confined spaces for extended periods. There’s also a need to plan and engineer the works appropriately, using best practice and emergent technologies to improve safety, reduce bedding impacts and to ensure the success of the coating campaign. This paper explores the challenges of major coating projects by discussing the importance of planning and preparation, the need to create a safe working environment within the confined space worksites, the role surface preparation plays in the success of coating projects, and finally the application of coatings and the challenges this operation can present. The key considerations are summarised in 10 specific conclusions as guidance to promote successful project outcomes.

Optimal Layout Design of a Liquefied Natural Gas FPSO: A Case Study

Abstract An liquefied natural gas (LNG) FPSO is a floating, production, storage, and offloading facility with a LNG plant, including all ancillary facilities. In contrast to commercial vessels, the various parts of the process are located topside and are distributed as modules that are installed on the deck. The design of an LNG FPSO requires many considerations such as international codes and standards, the owner's requirements, and the operation and maintenance philosophy. To resolve the many considerations in FPSO design, we proposed an optimization method for the topside arrangement in the previous study. Based on the previous study, an integrated optimization technique for an LNG FPSO is proposed to obtain the optimal principle dimensions, the arrangement of the hull tanks, and the layout of the topside modules and equipment that satisfies many requirements for not only the topside but also the hull. As a case study, the topside and hull layout of an LNG FPSO is optimized in terms of safety, economics, and stability. The case study shows that the proposed method can develop the optimal layout design of an LNG FPSO.

Turbulence modelling and role of compressibility on oil spilling from a damaged double hull tank

SummaryThe viscosity plays an important role, and a multiphase solver is necessary to numerically simulate the oil spilling from a damaged double hull tank (DHT). However, it is uncertain whether turbulence modelling is necessary, which turbulence model is suitable; and what the role of compressibility of the fluids is. This paper presents experimental and numerical investigations to address these issues for various cases representing different scenarios of the oil spilling, including grounding and collision. In the numerical investigations, various approaches to model the turbulence, including the large eddy simulation (LES), direct numerical simulation and the Reynolds average Navier–Stokes equation (RANS) with different turbulence models, are employed. Based on the investigations, it is suggested that the effective Reynolds numbers corresponding to both oil outflow and water inflow shall be considered when classifying the significance of the turbulence and selecting the appropriate turbulence models. This is confirmed by new lab tests considering the axial offset between the internal and the external holes on two hulls of the DHT. The investigations conclude for numerically simulating oil spilling from a damaged DHT that when the effective Re is smaller the RANS approaches should not be used and LES modelling should be employed; while when the effective Reynolds numbers is large, the RANS models may be used as they can give similar results to LES in terms of the height of the mixture in the ballast tank and discharge but costing much less CPU time. The investigation on the role of the compressibility of the fluid reveals that the compressibility of the fluid may be considerable in a small temporal‐spatial scale but plays an insignificant role on macroscopic process of the oil spilling. Copyright © 2016 John Wiley & Sons, Ltd.

Balancing Response Operations with Safety, the Environment and Commerce

ABSTRACT On January 23, 2010, a double hull tank vessel spilled nearly 9,500 barrels of high sulfur crude oil into the Sabine-Neches River (SBR) in Port Arthur, Texas. An ensuing evacuation of surrounding areas, coupled with the potential environmental impact and closure of the Intracoastal Waterway, elevated public, political and environmental concerns. Through an effective multi-agency Incident Command, rapid call up of abundant response resources to properly implement pre-identified response protocols, and the development of innovative response tactics, response managers successfully balanced environmental, commercial and safety concerns to execute a highly effective spill response in one of the busiest shipping thoroughfares in the United States. Collectively, the support of a cohesive Unified Command to execute operational strategies, and the RP's diligence in ensuring all needed response resources were quickly made available, enabled the command post to be stood down and the majority of the cleanup ...

二重船殻構造モデルタンクよりの油流出-IV : 傾斜タンクからの油流出実験

The amount of oil outflow to still water from an inclined bottom damaged model tank with a double hull was measured. The 1/50 scale model tank simulated the midship section of a VLCC. The oil outflow occurred due to the difference between the static pressure in the tank and the surrounding water at the bottom damage, and the displacement by water of oil contained in the double hull space below the damage. The experimental results showed that the amount of oil outflow is increased with the increasing difference between draught and oil level and the amount of oil outflow from the inclined double hull tank is larger than the non-inclined double hull tank. A method to predict the amount of oil outflow was applied to the inclined tank. The predicted and experimental results showed satisfactory agreement.