Cargo Containment Research Articles

Damping Effect of Reinforced Polyurethane Foam under Various Temperatures

Reinforced polyurethane foam (RPUF) is one of the important materials of Mark III type insulation systems used in liquefied natural gas (LNG) cargo containment systems. However, RPUF is the most difficult material to use with regard to its safety assessment, because there is little public and reliable data on its mechanical properties, and even some public data show relatively large differences. In this study, to investigate the structural response of the system under compressive loads such as sloshing action, time-dependent characteristics of RPUF were examined. A series of compressive load tests of the insulation system including RPUF under various temperature conditions was carried out using specimens with rectangular section. As a result, the relationship between deformation of RPUF and time is linear and dependent on the loading rate, so the concept of strain rate could be applied to the analysis of the insulation system. Also, we found that the spring constant tends to converge to a value as the loading rate increases and that the convergence level is dependent on temperature.

Acoustic emission monitoring of composite containment systems

This paper considers two different types of composite containment system, and two different types of acoustic emission (AE) monitoring approach. The first system is a composite reinforced pressure vessel (CRPV) which is monitored both during construction and in-service using a broadband modal acoustic emission (MAE) technique. The second system is a membrane cargo containment system which is monitored using both a global as well as a local AE technique. For the CRPV, the damage assessment is concerned mainly with the integrity of the composite outer layer at the construction stage, and possible fatigue cracking of the inner steel liner at the in-service stage. For the membrane tank, the damage assessment is concerned with locating and quantifying any abnormal porosities that might develop in-service. By comparing and contrasting the different types of structural system and different monitoring approaches inferences are drawn as to what role AE monitoring could take in the damage assessment of other types of composite containment system. (Detailed technical data have not been included, due to client confidentiality constraints.)

Liquefied natural gas flow in the insulation wall of a cargo containment system and its evaporation

Abstract A computational method was developed for temperature prediction in the insulation wall of a cargo containment system on ships carrying cryogenic fluids. A model problem was set up for complicated physical phenomena, such as multi-phase flow, multiple gas species, flow in a porous medium, and conjugate heat transfer. Specially designed codes were developed and hooked up with a Navier–Stokes equations solver to take care of the material properties of LNG and NG, such as the additional resistance in a porous medium, the evaporation mechanism, i.e., phase change, and mass transfer. The developed method was verified by examining the overall multi-phase flow behavior and temperature distribution in the physical domain of interest. The predicted solutions were in good agreement with the experimental data. The computational method can be adopted for use to many different structures, materials, and conditions and should be useful for the design of new LNG insulation wall systems.

Controlled cargo handling with piston fluid for pressurized liquid CO2 carrier

Abstract This study proposed a concept of the cargo handling system to load the pressurized liquid CO2 into the CO2 carrier and to offload the cargo out of the carrier with the piston fluid in a controlled way. The carrier was designed to transport a large amount of the captured CO2 in liquid phase. The cargo containment system consisted of pressure vessels to withstand the elevated pressure condition. Employment of the piston fluid enabled the pressurized liquid CO2 to enter and leave the cargo vessels without phase change or evaporation of the cargo. An increased loading and offloading rate seemed to cause generation of emulsion droplets in the interface of the piston liquid and the cargo. The droplets were separated into the cargo and the piston liquid by a conventional separator. Fresh water was considered excellent piston liquid since it was easily available and immiscible with the liquid CO2. As the cargo temperature decreased, CO2 gas was found to serve as the piston gas.

LNG 화물창 비계 시스템의 구조해석 및 진동 특성

LNG 화물창 비계 시스템의 구조해석 및 진동 특성

Fatigue design of steel containment cylinders for CNG ship application

A reliable methodology is required for fatigue design of steel cylinders for Compressed Natural Gas (CNG) carriers in order to meet target safety level at an acceptable cost. This includes description of physical models that represents actual long term fatigue capacity of the Cargo Containment cylinders. The design methodology includes length of welds, fabrication tolerances, fabrication methodology and non destructive testing. It also involves definition of characteristic values for loading and capacity in addition to recommended Design Fatigue Factors. Three alternative fatigue design procedures requiring different Design Fatigue Factors to achieve a system target safety level of annual probability of failure less or equal to 10 −5 are presented.

Design of a hybrid glass composite anchor for LNG cargo containment systems

Abstract Large cryogenic container for liquefied natural gas (LNG) should be joined to the inner hull of a ship. The minimum heat inflow, due to the large temperature difference between the LNG cargo container and inner hull, can induce considerable heat flux through the joined area. In this work, a hybrid composite anchor composed of two stainless steel caps and a glass fiber composite body was developed and optimized for strength, thermal stress and heat loss of the anchor. The stainless steel caps were adhesively bonded to the top and bottom areas of the glass composite body. The top stainless cap was then welded to the two stainless steel membranes, and the flange of the bottom stainless steel cap was bolt-fastened to the inner hull of a ship. The static adhesive strength and impact characteristics between the stainless steel caps and glass composite body of the hybrid glass composite anchor at the cryogenic temperature were investigated with respect to adhesive thickness. Finally, the optimal design for the hybrid glass composite anchor for the cryogenic containment systems of a LNG ship was suggested.

멤브레인형 LNG선 화물창 단열시스템의 수면낙하 내충격 응답해석 -II : 내충격 응답거동에 미치는 영향 고찰-

For the development of the original technique of structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In the previous study, the wet drop impact response analyses of CCS structure in membrane Mark III type LNG carriers were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. In this study, the characteristics of structural shock response behaviors of CCS structure were sufficiently figured out by careful examinations of the effects of specimen weight, drop height, incident angle, corrugation and stiffness of inner hull on its shock response behaviors. The shock response analysis of upward shooting fluid to inner hull was performed, and the reason of faster strain response than shock pressure one was also figured out.

멤브레인형 LNG선 화물창 단열시스템의 수면낙하 내충격 응답해석 -I : 검증을 통한 수치해석 기법 개발-

While the structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers has to be carried out in consideration of sloshing impact pressure, it is very difficult to figure out its dynamic response behaviors due to its very complex structural arrangements/materials and complicated phenomena of sloshing impact loading. For the development of its original technique, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In this study, for the exact understanding of dynamic response behavior of CCS structure in membrane Mark III type LNG carriers under sloshing impact pressure, its wet drop impact response analyses were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. It might be thought that the structural response behaviors of impact response analysis, such as impact pressure impulses and resulted strain time histories, generally showed very good agreement with experimental ones with very appropriate use of FSI analysis technique of LS-DYNA code, finite element modeling and material properties of CCS structure, finite element modeling and equation of state(EOS) of fluid domain.

Experimental investigation on the impact behavior of membrane-type LNG carrier insulation system

The aim of present paper was to experimentally investigate the dynamic strength characteristics of LNG cargo containment system under impact loads. A series of impact tests for full-scale membrane-type LNG insulation system has been undertaken using a custom-built drop test facility as varying height and weight of the drop object. Based on a series of repeated drop tests, displacement recovery was measured for the assessment of damping characteristic of insulation system. Crack initiation was also measured during the cyclic drop test.

Impact Strength Assessment of LNG Carrier Insulation System

The aim of present paper is to experimentally investigate the dynamic strength characteristics of LNG cargo containment system under impact loads. A series of impact tests for full-scale MARK III insulation system is undertaken using a custom-built drop test facility as varying height and weight of the drop object. Based on a series of repeated drop tests, displacement recovery was measured for the assessment of damping characteristic of insulation system. Crack initiation was also measured during the cyclic drop test. The quantitative relationship between impact load and crack initiation as well as the crack propagation with respect to drop number are derived.

Limit State Design Technology for a Membrane Type Liquid Natural Gas Cargo Containment System Under Sloshing Impacts

The aim of the present paper is to develop limit state design technology for cargo containment system structures of membrane type liquid natural gas (LNG) carriers, with the focus on sloshing impacts. The mechanical properties of plywood material making up the NO96 type LNG cargo containment insulation box structures are obtained from tensile coupon testing undertaken in the present study. The ultimate strength characteristics of the LNG cargo insulation box structure under quasi-static pressure action are investigated using ANSYS computer code. The dynamic failure behavior of the insulation box structure under sloshing impacts is examined using LS-DYNA3D computer code. Some important parameters, such as peak pressure and pressure duration time, which affect dynamic failure behavior, are varied in the LS-DYNA3D computations. The limit state design criteria for the insulation box structures under sloshing impacts are developed. Problem areas to be resolved are discussed.

New bend on budding

COPII vesicles form from the endoplasmic reticulum (ER). Now, Marcus Lee, Randy Schekman (University of California, Berkeley), and Lelio Orci (University of Geneva, Switzerland) find that insertion of the amphipathic α helix of the Sar1 GTPase causes membrane deformation that initiates, and eventually ends, this vesicle formation process. Figure Sar1-GTP induces membrane curvature and tubule formation. The group investigated how COPII coats shape the ER by examining in isolation how each set of COPII proteins—Sar1, Sec23/24, and Sec13/31—influences membrane curvature. When activated Sar1-GTP was incubated with spherical liposomes, the researchers saw that the spheres strikingly developed long, narrow tubules ∼26 nm in diameter. They then determined that insertion of Sar1's α helix into the lipid bilayer is responsible for this transformation. “When you stick an object into 1 of 2 layers in a bilayer, you cause membrane deformation that results in extra surface tension. The most favorable way to relieve this tension is by forming tubules,” Schekman explains. The group also found that Sec23/24 could bend membranes. Rather than inserting a protein domain into the lipid bilayer, this complex forms a concave, bowtie-shaped dimer that presumably presses the membrane against its underbelly to create membrane curvature. Sec23/24 dimers likely become organized into a lattice by the Sec13/31 scaffolding complex to ultimately form vesicles 70 nm in diameter. Schekman's and Orci's groups think that Sar1 initiates membrane deformation, and then Sec23/24 recruitment “captures” the bent membranes to better mold the curvature, with help from Sec13/31 for cargo containment. Although Sec23/24 and Sec13/31 complexes could create budded vesicles on spherical liposomes, the buds rarely closed off to form free vesicles when the Sar1 helix was absent. “This is an unexpected finding,” says Schekman. “We think that the curvature induced by Sar1 is necessary at this point to press the neck of the vesicle together to complete the fission process.” Reference: Lee, M.C., et al. 2005. Cell. 122:605–617. [PubMed]

Analysis of Vapor Insulation System for Cargo Tank of LNG and LH2 Carrier

For storage and transport of LNG or LH 2 (liquefied hydrogen gas) it is of great importance to control the loss of boil off gas, and the thermal insulation and the effective utilization of the boil off gas are here playing an important roll. Regarding the reduction of the evaporation quantity of the cargo, increasing the insulation thickness is probably the most common solutions chosen. But due to the fact that there might be limited space available in hold space, other method could be preferable. The authors, however, have directed their focus of engineering on a recovery of cold energy imposed on the evaporated vapor and tried to take advantage of the boil off gas which is a result of heat passing through the protective thermal insulation from the surrounding atmosphere. This theory of Vapor insulation system was applied to the spherical tanks of LNG carrier and LH 2 carrier. Cold nitrogen gas which was heat-exchanged with the boiled off LNG or LH 2 vapor was introduced into the annular space around the tank, in which the gas flows upward along the tank surface bringing the heat absorbed from the hold space out of the cargo containment system before reaching the valuable liquid cargo. In order to optimize the Vapor insulation system, the effect of several important parameters such as gas flow quantity, gas temperature and location of gas passage and others were analyzed carefully and realistic examples of design were proposed.

LIGHTERING AND SALVAGE OF THE TANK BARGE OCEAN 255 IN AFTERMATH OF A COLLISION, EXPLOSION, AND FIRE IN TAMPA BAY, FLORIDA, AUGUST 1993

ABSTRACT In the early morning hours of August 10, 1993, the 14,000 gross ton tank barge Ocean 255, loaded with over 200,000 barrels of aviation fuel, premium and regular gasolines, and diesel fuel collided with the M/V Balsa 37 west of the Sunshine Skyway Bridge in Tampa Bay, Florida. The energy of the collision resulted in an explosion and fire that completely enveloped the 546 foot barge. The fire burned intensely for over 18 hours while the barge lay grounded north of the main ship channel leading into the Port of Tampa. After the fire was extinguished, the transfer of the remaining cargo, to remove the very prominent threat from explosion and pollution, fell to the U.S. Coast Guard's National Strike Force. The Ocean 255's cargo containment, transfer, venting, and safety systems were completely destroyed, and its stability and hull integrity were in question. The operation was faced with uncertain weather including the possibility of a hurricane developing, frequent strong afternoon thunderstorms and squalls, strong currents, and a vessel that was a virtual time bomb. The entire amount of remaining cargo was transferred in eight days of around-the-clock pumping operations. The damage assessment after the explosion complicated the plans for lightering and salvage operations. However, action and site safety plans, and the formation of integrated teams developed by Maritrans LP (owners of the barge and the responsible party) and the National Strike Force, resulted in a successful and safe removal of the remaining 180,000 barrels of highly flammable cargo without further pollution of the waters of Tampa Bay and the State of Florida.

Safety features on LNG ships

The technology to transport liquefied natural gas (LNG) safely by sea is well established and many variations of cargo containment systems have been tested and developed since the early 1950s. Examples of four current LNG ships incorporating different containment systems are briefly described. Safety features are examined, now considered standard practice on a modern LNG carrier, which have made a major contribution to the outstandingly good record of LNG ship operations. Examples are given of some LNG ship casualty incidents.

Study on Crack Resistance Performance of Continuous Glassfiber Reinforced Polyurethane Foam (2 nd Report)

The purpose of this study is to make a quantitative evaluation of the effect of glassfibers on the increased crack resistance performance of reinforced PUF (polyurethane foam), which was developed to meet the requirements of insulation material for the TGZ Mark III cargo containment system of LNG carriers. In this report, the crack extension behavior and the fracture toughness of reinforced PUF (R-PUF) have been examined based on compact tension tests at room and low temperature in comparison with those of non-reinforced PUF (G-PUF) following the first report, in which the three-point bending test results at room temperature were shown and discussed.In particular, a different behavior in crack extension modes and fracture toughness of R-PUF has been experimentally characterized depending on direction of a notch, tempearture and crosshead speed in the compact tension tests. The acoustic emission analyses and the finite element simulations proposed in the previous report have been shown to be effective in comparing the fracture behavior of R-PUF with that of G-PUF in the compact tension tests as well as the case of three-point bending tests.

Study on Crack Resistance Performance of Continuous Glassfiber Reinforced Polyurethane Foam (1st Report)

Rigid PUF (polyurethane foam) is one of materials for in-ground LNG storage tanks which have been successfully constructed since 1970. For LNG carriers, however, it is necessary to use a material having sufficient strength to withstand cyclic load and impact load caused by hull motion in waves and hull deformation etc., and having excellent resistance to crack propagation as well. To meet this requirement, reinforced PUF consisting of continuous glassfiber uniformly dispersed in rigid PUF has been developed especially for TGZ Mark III cargo containment system.The present paper aims at making a quantitative evaluation of the reinforcing effect of glassfiber in reinforced PUF from a viewpoint of increased crack resistance performance. In this report, crack extension behavior and fracture toughness of reinforced PUF have been examined in detail in comparison with those of rigid PUF under a three-point bending test on notched beam specimens at room temperature. Acoustic emission analyses and finite element simulations have been shown to be successful in comparing the fracture behavior of reinforced PUF with that of rigid PUF.

Submarine transportation of hydrocarbons from the arctic

A submarine tanker system is presented as a technically feasible, economically viable transportation system to move oil and gas from the Arctic to markets in Western Europe and North America. Proven by over two decades of nuclear submarine operations in the Arctic, submarines can safely and reliably transport cargo under ice over virtually any proposed shipping route in the Arctic, with assurance of year-round delivery at uniform, predictable schedule intervals. To establish the technical feasibility of commercial cargo submarines, baseline designs for a 181,400 dwt submarine oil tanker and a 140,000 m 3 submarine LNG tanker have been developed, using either nuclear or conventionally fueled propulsion plants. The submarine oil tanker design is based on a contract design developed in the 1960's, which has been refined to comply with recent oil pollution regulations. The submarine LNG tanker is an adaptation of that basic design to accommodate cryogenic cargo containment and transfer systems. Approximate characteristics of both designs have been identified, including ship dimensions, cargo system arrangement, propulsion machinery, and operational capabilities. Both submarines are designed to load cargo at a submerged terminal, and to offload cargo in the surfaced mode. Approximate transportation costs are provided for both the oil and LNG submarine tanker systems.

Hazard evaluation of chemicals for bulk marine shipment

For economic reasons most chemicals used in large quantities by industry are transported in tank vessels. These chemicals range in properties from essentially harmless to highly dangerous. Although the United States and IMCO require certain minimum data before classifying a new chemical to be transported in bulk, no formal system exists to correlate these data with specific shipboard requirements such as the location of the tank within the vessel, gauging and venting systems, or cargo overfill protection. Developing guidelines for the evaluation of chemicals is a two part problem. First, the inherent hazards of a chemical (the hazards of a product when it is released, without regard to its cargo containment system) must be investigated. In the second part of the evaluation, these hazards are then correlated with specific shipboards requirements as mentioned above. This paper outlines the essential elements for developing a comprehensive system of hazard evaluation for bulk liquid chemicals.