ABSTRACT Interest in oil and gas exploration and production in offshore arctic regions has increased over the past several years. It is estimated that the arctic region holds about 30 percent of the world's undiscovered conventional natural gas and about 13 percent of the undiscovered oil reserves as determined by the U.S. Geological Survey (USGS, 2012). Although oil and gas exploration activities in the arctic began in the 1960's and 1970's, it has only been in recent years that larger-scale offshore development prospects have been considered viable. However, significant technical challenges need to be addressed to safely deploy and operate assets in the arctic or near-arctic regions. One primary issue will be the integrity of materials placed in service at temperatures down to −60°C (−76°F), with fracture toughness of key concern. It is generally accepted that structural steel plate and pipe can provide good toughness performance at these temperature extremes. However, limited work has been carried out to assess weld performance for such low temperatures other than by Charpy V-notch (CVN) impact tests. While there are commercially available weld consumables suitable for low temperature service, consumables typically used for construction of oil and gas infrastructure using carbon and high strength low alloy (HSLA) steels have not been commonly designed for use at arctic temperatures. Considerable research has been carried out to develop base materials for arctic conditions, and suitable materials for arctic infrastructure are commercially available. However, performance of weld consumables in arctic environments remains an active area of research and development. Early stage progress on arctic weld consumable characterization was presented by EWI at the ISOPE 2015 Conference (McGaughy and Zelenak, 2015), which revealed that fracture toughness properties in welds at arctic temperatures were often low and demonstrated high levels of scatter. Other papers published over the past three decades have presented similar trends (Akselsen, Ostby and Thaulow, 2011, Zia-Ebrahimi, 1985, Graville and Tyson, 1992). Thus, development of optimized welding parameters and consumables that can consistently provide acceptable levels of fracture toughness at low temperatures remains a gap for safe and efficient exploration and production in arctic regions. This paper will present results obtained from recent project work to further characterize the fracture toughness properties of numerous flux cored arc welding (FCAW) and submerged arc welding (SAW) consumables designed for arctic service. This project was sponsored by the EWI Strategic Technology Committee for Oil & Gas, which consists of oil and gas operating companies, steel producers, welding equipment and consumable suppliers, engineering companies and welding contractor companies. The program utilized steel plate and welding consumable donations from several suppliers. The objective of this work is to provide general engineering guidance for welding of infrastructure intended for arctic service without making supplier-to-supplier comparisons. Therefore, the identity of the plate steel and various welding consumables is not revealed in this paper. Regardless, the results provide one of the first independently-produced data sets of weld metal fracture toughness (CTOD) for arctic conditions and identifies weld process characteristics that can have influence over toughness control. The results can aid in weld consumable selection and design of weld procedures that will provide required mechanical properties to assure weld integrity for fracture control under arctic service conditions.

ABSTRACT A fiber optic spectrometry system with a miniature nearinfrared (range of 640∼1050 nm) spectrometer was designed to test and evaluate the performance of the mini-spectrometer in extremely cold conditions. The relationship between the output of the spectrometer and temperature was examined over the range of −50°C to 30°C, and the linear working range was derived by modeling the output of the spectrometer. The signal output was calculated and modeled to create a calibration method to correct the temperature-induced biases. Results indicated that the spectrometer used in this system can work stably in cold polar environment, and the designed calibration method can at least correct the 894 counts of signal output, which is good enough for the system. INTRODUCTION In the last few decades, the environment of the Arctic is undergoing tremendous changes, especially in terms of sea ice. The sea ice in Arctic is not only greatly reduced in coverage, but the multiyear ice is also rapidly melting (Comiso JC et al., 2007; Comiso JC, 2012), which causes significant influence to Arctic ecological environment, marine ecosystem and global climate changes (Serreze MC et al., 2007; Serreze MC et al., 2012). These changes are determined by many factors, like ocean current movement, geological movement in Arctic, however, it denotes that solar radiation is one of the most important reasons (Perovich DK et al., 2007; Perovich DK et al., 2011). Based on the solar radiation spectrum, it can be find that almost half of the energy is concentrated in the nearinfrared (Iqbal M, 2012). Therefore, it's necessary to measure the intensity of the near-infrared solar radiation in sea ice and find out how it affects the climate in Arctic. However, due to many factors, research in this area is still limited, the most important reason is the low-temperature environment of the Arctic led to many instruments and equipment can not to be deployed and used in the field.

ABSTRACT Aluminium is known as a safe and suitable material for offshore installations. Factors that favour aluminium are low weight, no need for surface treatment and low maintenance costs. Though aluminium has a high strength-to-weight ratio, it suffers from strength reduction in heat affected zones when welded. The strength of the soft zones is often dimensioning in design, and the ability to predict the strength reduction is important for fully utilizing the potential of aluminium as a structural material. In the current study, the cross weld strength of EN AW 6082-T6 and EN AW 5083-H321 as a function of wall thickness at room temperature and at −60°C ("arctic temperature") was tested. The main objectives were to verify that the materials and the weldments are not deteriorated at low temperatures, and to check if using additional reduction factors for the heat affected zones for plates and extrusions thicker than 15 mm as specified in the design standard EN 1999–1–1 is correct. The results show that there is no reduction in strength for low temperatures, nor for plates and extrusions thicker than 15 mm. Based on the results in this study, changes in EN 1999–1–1 are recommended. INTRODUCTION Unlike body-centred cubic (BCC) metals, the yield and strength temperature sensitivity of face-centred cubic (FCC) materials, such as aluminium (Al) alloys, is negligible when lowering the temperature below room temperature (Hertzberg 1996). Because of the high specific strength, good corrosion resistance and good mechanical properties at low temperature, Al-alloys are often used for low temperature conditions such as cryogenic applications (e.g. Liquefied Natural Gas (LNG) tanks and space/aeronautics). Thus, the low temperature characterization found in the literature focus on test temperatures far below −60°C. In BCC materials, such as steels, the dislocation width is narrow and the Peierls stress increases rapidly with decreasing temperature, thus the yield stress will increase strongly with decreasing temperature. An important consequence of this for BCC materials is that the yield stress can rise to such high levels that only a very limited plastic zone ahead of a crack will occur before unstable (brittle) fracture results. This material brittleness will not occur in FCC alloys (Aluminium), and a ductile fracture mode will prevail.

ABSTRACT The fabrication of structures for Arctic applications is expected to face major challenges when it comes to the fracture toughness of the heat affected zone and the weld metal. Although the initial base metal toughness may be excellent, a severe toughness deterioration normally occurs as result of the rapid heating and cooling cycles in welding. The present investigation addresses tensile behavior and toughness properties of 32 and 50 mm thick 420 MPa plates, including tensile testing at both room temperature and −60°C, and Charpy V impact toughness and CTOD fracture toughness at −60°C. The welds were deposited by gas shielded flux cored arc welding using a heat input of 2-2.4 kJ/mm. The results showed a dramatic reduction in the fracture toughness after welding, i.e., from CTOD level above 2.5 mm to below 0.25 mm for the 50 mm plate, and from ~ 2 mm to the lowest value of 0.12 mm for the 32mm plate. The Charpy V toughness appeared to be good for the 50 mm, both for the heat affected zone and the weld metal, while the 32 mm plate suffered from low values in the weld metal root area. The results for the 50 mm thick plate are very promising, particularly for use in the temperature range down to −20 to −40°C. INTRODUCTION The oil and gas industry is moving north due to the large oil and gas reserves. For example, a preliminary assessment by the US Geological Survey suggests the Arctic seabed may hold as much as about 30% of the world's undiscovered gas and 13% of the world's undiscovered oil (Gautier et al, 2009), mostly offshore under less than 500 meters of water. In these areas, the temperature may occasionally fall below −30 to −40°C, which represents new challenges to the materials. Normally, structural steels and pipelines may easily satisfy toughness requirements at such low temperature. However, welding tends to be very harmful to low temperature fracture toughness. Both the heat affected zone (HAZ) and the weld metal may fail in providing sufficient toughness (e.g., Akselsen et al, 2011; Østby et al, 2011; Akselsen et al, 2012; Akselsen and Østby, 2014).

ABSTRACT This paper focuses on the investigation, assessment and comparison of a 420 MPa structural steel Charpy (CVN and pre-cracked) and fatigue crack growth rate test at different temperature spanning from room temperature to −120°C. Since weldments constitute the most probable location for fatigue-related failures, the material have been weld simulated in order to isolate and represent its Coarse Grained Heat Affected Zone. Results are analyzed and compared and an attempt to relate the Fatigue Ductile to Brittle transition (FDBT) and the static Ductile to brittle transition (DBT) temperatures is attempted in order to exploit the possibility to avoid or limit the most expensive and time consuming crack growth rate testing. INTRODUCTION In the last years, a great push for oil and gas explorations in the Arctic regions (Gautier, Bird, Charpentier, Grantz, Houseknecht, Klett, Moore, Pitman, Schenk and Schuenemeyer, 2009) together with the increase possibility of an alternative and more direct Asia-North Europe connection kept the interest of oil and gas and maritime industry high. The development of oil and gas fields in the arctic brings to the table several challenges due to the cold and harsh climate; when it comes to the use of structural ferritic steels, particular concerns relate to their low-temperature properties. More precisely, when it comes to structural integrity of offshore structures built with ferritic steels, Ductile to Brittle Transition (DBT) and Fatigue Ductile to Brittle Transition (FDBT) needs to be carefully assessed in order to avoid unexpected catastrophic failures. It is long known that, as ferritic steels operates at lower temperatures, they undergo a transition from a ductile shear-dominated to a brittle cleavage dominated fracture mode. This phenomenon is known as Ductile to Brittle Transition (DBT) and it is commonly quantified through the typical fracture mechanics parameters, i.e. CTOD (Crack Tip Opening Displacement), Charpy impact energy C v , K Ic or J-integral values. A schematic is presented in Fig 1.

Abstract The purpose of this study is to identify the design sloshing load and evaluate the structural safety of the sprayed polyurethane foam (PUF) with density of 45 kg/m 3 , which is applied as an insulation material of full containment onshore LNG storage tank, under the seismic leakage condition. To do this, first, the design sloshing load was evaluated as per relevant design codes and the fluid structure interaction (FSI) simulations under the seismic load corresponding to the safety shutdown earthquake-aftershock (SSE aft ) after the inner tank leakage. From the result, the design drop height corresponding to the design sloshing load was determined through a series of preliminary wet drop tests. And then, the sloshing safety assessment of PUF was carried out using the wet drop test and simulation under the defined design drop height. Here, the wet drop simulations were performed using the established PUF material model by static and dynamic material tests and FSI simulation technique. Based on the results of the extensive wet drop tests and simulations with the design sloshing pressure, it was verified that the PUF sprayed inside the outer tank in the LNG storage tank considered has a sufficient structural safety under the design sloshing load caused by the LNG leakage and seismic load of SSEaftershock. Introduction Hyundai modular LNG storage tank (HMLST) has been first developed with the modular design concept for an onshore LNG project, which is composed of the inner tank of 9% Ni steel and the outer tank of lightweight steel-concrete panel reinforced with carbon steel primary member. Comparing the insulation system of HMLST with that of the conventional LNG storage tank, its insulation system features the polyurethane foam with the density of 45kg/m 3 (PUF-45) sprayed inside the outer tank for securing both high insulating performance and structural integrity of the outer tank during the service life and accidental state. In case of LNG leakage in the inner tank, the outer tank should contain LNG without any deterioration of PUF-45 under the seismic load. That is, PUF sprayed on the wall of outer tank should sustain the sloshing load induced by leaked LNG under the seismic load. Provided that the PUF-45 of outer tank is damaged or collapsed by the sloshing load after LNG leakage, the spilled LNG contacts directly to the skin plate of outer tank. Therefore, it is very crucial that PUF-45 resists against the sloshing load by the seismic to secure the structural integrity of outer tank under the LNG leakage condition. Generally, since sloshing by a seismic excitation in a LNG storage tank can produce the dynamic fluid motions, which lead to high impact pressure on the PUF-45 inside the outer tank, the dynamic failure of PUF-45 during sloshing events should be considered in the design stage of LNG storage tank. According to previous study (Lee et al., 2014), it is well known that PUF has a visco plastic behavior under the dynamic loading conditions. Therefore, in order to quantitatively evaluate the structural safety of PUF-45 under the sloshing impact, it is also required to consider the visco-plastic behavior of PUF under dynamic loading conditions (Lee et al., 2015).

Abstract The development of oil and gas fields in the arctic brings to the table several challenges in the use of structural steels, particularly concerning their low-temperature properties. Among others, also fatigue behavior needs to be accounted for when using structural steels for arctic applications. As for static fracture, ferritic steels experience a fatigue ductile to brittle transition (FDBT) when temperature is decreased below a certain temperature. This may result in higher crack growth rate and, consequently, unpredicted fatigue-related failure. In order to shed some more light on this phenomenon, fatigue crack growth tests have been performed on a 420 MPa structural steel weld simulated coarse grained heat affected zone (CGHAZ) at different temperatures: room temperature, -30, -60, -90 and -120 °C, with -60 °C considered as a possible design temperature relevant for the most extreme arctic areas. Post-mortem fracture surface investigations have been also conducted in order to confirm the expected switch in fatigue crack growth mechanisms as temperature is lowered below the FDBT temperature. Finally, two analytical equations, valid for temperature ranges above the FDBT, were established based on the experimental results to relate yield strength and temperature variation of the Paris law constants. These are used to quantify the temperature impact on the designed fatigue life, and the results are compared to the actual design rules (BS 9710). INTRODUCTION Exploration of oil and gas in the Arctic regions is increasing due to the large share of the remaining resources (estimates indicate that about 13% of the remaining oil and 1 gas resources is located in the northern regions (Gautier, Bird, Charpentier, Grantz, Houseknecht, Klett, Moore, Pitman, Schenk and Schuenemeyer, 2009) and the possibility for an alternative and direct Asia-Europe connection route keep both oil and gas and maritime industry interest growing. However, the harsh and cold climate characteristic of the arctic regions imposes several challenges when it comes to materials integrity. The combination of long and repeated ice loading together with operating temperatures which are typically lower than the ones at which the offshore industry is used to work with, demands for new research-based development in order to avoid catastrophic leakage and failures. It is well known, in fact, that as ferritic steels is subjected to sub-zero temperature, they undergo a transition from stable, ductile fracture to unstable, brittle fracture. While for pure materials, the transition may occur very suddenly at a particular temperature, for many materials used in practice the transition occurs over a range of temperatures. This causes difficulties when trying to define a single transition temperature and no universally recognized and specific criterion has been established. Similarly, a fatigue ductile to brittle transition (FDBT) can be observed in ferritic steels. Fig. 1 summarizes the qualitative fatigue crack growth behavior variation for ferritic steels as temperature is lowered.

Abstract It is well known that metallic materials, such as ferritic steels, the yield and tensile strength increases with decreasing temperature. For some steels, the level and length of the Lüders band also increases with decreasing temperature. Taking into account these effects of temperature in the constitutive equations for steels can be of great importance for higher utilization of steel, requirement of fracture toughness and mismatch conditions of welds. A detailed study addressing this issue is necessary in order to have tools and methods to take these effects into account. This is both concerning the definition and suggestions of procedures to perform tensile testing below room temperature, and improved constitutive models that correctly describe the effects of temperature. This paper will present a model that can describe temperature dependent stress-strain curves based on the tensile testing of base materials and weld thermal simulated microstructures (CGHAZ and ICCGHAZ) from a 420 MPa steel at 0, −30, −60 and -90°C. The dependency of yield stress, tensile strength, Lüders strain as well as strain hardening on temperature will be discussed. For situations where tensile test data is not available, a correction of yield stress and Lüders band development at low temperature based on the yield stress at room temperature is proposed. The effect of temperature dependent material properties on brittle fracture is studied using cohesive zone model.

Abstract Fracture assessments of circumferential surface flaws in pipeline girth welds made in field conditions, including deep water steel catenary risers (SCRs), play a key role in current applications of engineering critical assessment (ECA) procedures for repair decisions and life-extension programs of these engineering structures. These approaches rely upon crack growth resistance ( J -Δ a or CTOD-Δ a ) curves (also termed R-curves) to characterize crack extension followed by crack instability of the material thereby allowing the specification of critical crack sizes based on the predicted growth of crack-like defects under service conditions. Current standardization efforts now underway (Det Norske Veritas, 2006; Cravero and Ruggieri, 2007b, a; Shen and Tyson, 2009) advocate the use of single edge notch tension specimens (often termed SE(T) or SENT crack configurations) to measure experimental Rcurves more applicable to high pressure piping systems, including girth welds of marine steel risers. To the extent that J describes the crack-tip conditions with increased crack extension and, further, that a unique J -CTOD relationship holds true for stationary and growing cracks, both J -Δ a and CTOD-Δ a curves equally characterize well the crack growth resistance behavior for the tested material. However, because of the widespread use of the CTOD parameter since its introduction in the 70s, when early development conducted at the Welding Institute introduced the concept of a CTOD design curve (Burdekin and Dawes, 1966; Harrison et al., 1979), current defect assessment procedures adopted by the oil and gas industry favor the utilization of CTOD- R curves rather than J -resistance measurements.

Abstract An experimental study of the role of sub-zero temperature impact damage and subsequent freeze-thaw exposure on post impact compression strength of quasi-isotropic glass fibre reinforced vinyl ester resin composite materials using non-crimp reinforcements typically applied in the marine industry is presented. Specimens cut from composite plates were impact loaded at two different temperatures according to ASTM D7136, then immersed in fresh water until saturation before being subjected to various number of ASTM C666 freeze-thaw cycles. After the freeze-thaw cycles, the specimens were compression tested using a Boeing anti-buckling device according to ASTM D7137.

Abstract The present article discusses the cyclic material behavior in form of stress-life, strain-life and cyclic stress-strain curves of three different nodular cast iron materials derived by specimens taken from heavywalled cast blocks. Results are shown for static as well as cyclic stress and strain controlled tests performed at room temperature. Additionally, issues concerning the materials' behavior in low temperature application are also discussed through results gained by cyclic stress controlled tests at ϑ = −40 °C for alternating, R 0 =−1, and tensile loading, R 0 =0. For comparison, the corresponding static material values and the results of notch impact tests both at room temperature and ϑ = −40 °C are also given.

Abstract Over the past decade, it has been a continuously growing interest in exploration of oil and gas in the arctic region. The harsh, cold climate imposes challenging tasks which concern the structural integrity of steels and their weldments. Specific knowledge of metals behavior in such conditions is therefore mandatory in order to provide sufficient robustness. Within this framework, the present paper focuses on the fatigue properties of steels with the intention to provide a comprehensive review of the open literature about the effect of low temperature on the different aspects of the fatigue life of steels and their weldments. The main objective is therefore to provide a reliable basis for suggestions of necessary testing of low temperature fatigue in steels.

ABSTRACT SINTEF in Norway has run a project called "Arctic Materials" dedicated to establish criteria and solutions for achieving safe and cost effective use of materials for exploration and production of oil and gas in arctic areas. Trelleborg Offshore Norway has developed three elastomer compounds with improved low temperature resistances that have been tested in this project. The main focus has been to develop materials which maintain the original flexible behavior at low temperatures and that provide a set of useful properties for producing elastomeric parts to meet demanding requirements in exploration and production of Oil and Gas in Arctic Areas. Glass transition temperatures, mechanical properties (impact resistance, tensile and tear) and resistance to weathering have been tested. The potential for use of these elastomer materials in Arctic areas has been demonstrated.

ABSTRACT As high manganese austenitic steel has been developed to replace 9%Ni, 304 stainless steels and Al5083 alloy, widely used in cryogenic applications, much attention are now focused on the development of the associated welding consumable in order to maximize the use of the high manganese steel under cryogenic environment. In particular, flux cored arc welding consumable which allows all-positional welding for high-Mn steel has been required to fabricate LNG tank. In the present study, the microstructure and mechanical properties were investigated for high manganese weld metals produced by metal cored arc welding consumables. Flux cored wires are then designed with both fluxes containing less than 10% of acidic slag formers such as rutile(TiO 2 ) and silica(SiO 2 ) for all positional welding and austenite stabilizing elements such as C, Mn and Ni for increasing toughness at cryogenic temperature and strength at room temperature. Microstructural and mechanical properties are then evaluated as a function of alloy composition variations. The weld metals produced by newly-developed high manganese cryogenic flux cored welding consumables show the charpy impact toughness of larger than 54J at -196°C and the yield strength of 400MPa at room temperature. This result encourages the extensive applications to cryogenic services with a big cost competitiveness.

ABSTRACT: Combined in situ tensile testing in a high resolution field emission scanning electron microscope (FESEM) and electron backscatter diffraction (EBSD) measurements was carried out at room temperature and −60°C on weld thermal simulated HSLA steel. EBSD measurements were conducted at different elongation levels to look for changes in the microstructure. The experiments reveal that retained austenite transforms to martensite under deformation at −60°C. This is not the case at room temperature where phase transformation does not occur in the majority of the retained austenite grains. INTRODUCTION It is estimated that approximately 30% of the remaining gas reserves and 13% of the remaining oil reserves may be located in the arctic region, north of the polar circle (Gautier et al., 2009). Oil and gas activities in these regions have to cope with extreme climatic conditions from ice, snow and very low temperatures. It is therefore of vital importance to apply robust materials for safe and cost-effective hydrocarbon exploration and production in arctic environments. The parent microstructure of high strength low alloy (HSLA) steels has a fine balance between strength and toughness at low temperatures. However, these favourable mechanical properties may be altered during welding. Brittle phases, such as martensite-austenite (M-A) islands, may form during the weld cycles (Chen et al., 1984; Akselsen et al., 1987 and 1988; Li et al., 2001), and this can lead to brittle fracture at low temperatures. Increased knowledge and understanding of these phases and how they influence the low temperature behaviour of HSLA steels is therefore of great interest. Today it is possible to conduct microstructure examinations of steels during in situ tensile testing from elevated to sub zero temperatures inside the high resolution field emission scanning microscope (FESEM) (Karlsen et al., 2009).

ABSTRACT Martensite transformation of Supermartensitic steel during welding cycle was in-situ observed by using high temperature laser scanning confocal microscopy and X-ray diffraction by Synchrotron radiation. From the test results, X-ray diffraction integration strength of austenite was increased by the influence of the martensite transformation stress. INTRODUCTION Supermartensitic steel (14CrNiMo) is a candidate as a weld metal for joining of ultra-high strength steels. For preventing the cold cracking problem, the austenite phase is effective due to its nature of hydrogen absorption and existing of austenite phase increases toughness of weld metal(Bhadeshia and Edmonds, 1979; Park et al., 2002; Pressouyre and Bernstein, 1981; Sakuma et al., 1991). Moreover, the residual stress can be decreased by introducing the martensite transformation expansion(Shiga, 2000; Shiga et al., 2007). On the other hand, too much retained austenite could decrease the strength of Supermartensitic steel. Hence, determination of the retained austenite is important in Supermartensitic steel. X-ray diffraction techniques have been widely used for measuring the retained austenite (Averbach and Cohen, 1948; Ball and Kelly, 1982; Durnin and Ridal, 1968; Miller, 1964; Zhang et al., 2000). The crystal is more nearly perfect and has a lower diffracting power. This decrease in the integrated intensity of the diffracted beam as the crystal becomes more nearly perfect is called extinction. Generally speaking, the change in specific volume accompanying the transformation of austenite to martensite sets up nonuniform strains in both phases so severe that both kinds of crystals can be considered highly imperfect(Cullity and Stock, 2001). Therefore, extinction is absent because of the very nature of martensite steel. According to the weld metal, the austenite grain grows after fully austenitization. The initiation of the matensite transformation (diffusionless shear transforamtion) greatly affects the surrounding austenite parent phase.

There has been a wide range of research and application activities worldwide in the strain-based design (SBD) of pipelines. SBD may be applied to pipelines expected to experience large longitudinal strains typically associated with ground movement. This paper describes a PRCI and US DOT co-funded project aimed at developing tensile strain capacity models and procedures. The materials tested so far include 12.75-inch (324-mm) OD × 0.5-inch (12.7 mm) wall thickness ERW pipes manufactured by two pipe mills. The testing of higher grade and larger diameter pipes is planned but not reported here. The initial attempts at correlating the small-scale material properties with the large-scale experimental test results are the focus of this paper. Considerable coverage is given to the results of the small-scale material characterization tests. Large-scale tests, including curved wide plates and full-scale pipes, are briefly described, while the details are referred to a companion paper. Samples of post-test metallurgical examinations are presented. Finite element analysis of selected large-scale tests shows that multiple interacting factors affect the tensile strain capacity. The varied degree of agreement between the experimental and analysis results demonstrates the importance of understanding and accounting for material property variations. The paper concludes with a brief status update on the current work and emerging issues related to SBD. INTRODUCTION Background Strain-based design (SBD) is often necessary for pipelines expected to experience large displacement loading. There have been a number of focused research efforts world-wide aimed at the development of procedures and even standards for SBD. These efforts are highlighted in the two dedicated symposia of this conference in 2007 and 2008. In 2008, OMAE and International Pipeline Conference (IPC) also held focused sessions for SBD. In North America, the need for SBD is primarily driven by anticipated pipeline projects in the far north where pipelines will traverse regions of discontinuous permafrost.

Understanding of local behavior of sloshing pressure is essential for design of LNG containment systems, particularly for operations in offshore environments. Extensive sloshing experiments revealed that local pressures at temporal resolution on the order of 20 kHz and spatial resolution of 5mm for scaled models up to 1:20 are stochastic; peak pressure varies dramatically from cycle to cycle even under a simple harmonic excitation in one degree of freedom. In addition, such pressures are strong functions of local geometry such as corrugations and raised invar edges, as well as physical and thermal conditions of the ullage. As such, the phenomenon is very challenging for predictions using existing numerical algorithms. To obtain proper design values for the containment system, scaled model tests must address the above parameters and appropriate scaling laws identified. In this paper, we assimilate fundamental aspects of sloshing from first principles to identify relevant dimensionless numbers necessary for dynamic similarity of scaled model tests involving local pressures. Various experiments were carried out to support relevance of such dimensionless numbers; experimental results and their implication in scaling will be discussed in the paper. INTRODUCTION Impulsive loads that resulted from body entry into fluids had been extensively studied from the turn of the 20 th century. von Kármán (1929) and Wagner (1932) employed potential flow theory to study the 2-D cylinder and wedge entry problem respectively by neglecting the effects of gravity (fluid acceleration during impact are much larger than that of gravity). The potential function was assumed to be φ = 0 at the mean free surface z = 0 . This condition was subsequently relaxed by many investigators, noticeably that of Zhao and Faltinsen (1993) and Zhang, Yue and Tanizawa (1996). Solutions obtained from these techniques are deterministic, i.e. the same initial and boundary conditions always lead to the same solutions.

ABSTRACT S-N fatigue tests were carried out on weldments of 9% nickel steel, which is often used in cryogenic applications. The objective was to confirm that the fatigue behavior at cryogenic temperature was at least as good as that at room temperature. The cruciform specimens were similar in configuration to those used to develop the F-curve, which is found in UK practice and generally recognized by other structural design standards worldwide. The specimens were left as-welded. Three tests were conducted at both room and cryogenic temperature and at two different stress range levels. Comparison of the results showed that the cryogenic condition improved the life noticeably at both stress range levels. This finding was not unexpected based on literature evidence as to the reduction in crack growth rate at lower temperatures for this particular material. Prior work demonstrated that 9% nickel weldments can be safely analyzed by the usual S-N curves for carbon steel weldments when at room temperature. Hence, this latest finding means the same conclusion applies to 9% nickel weldments at cryogenic temperatures. INTRODUCTION Low nickel ferritic steels, such as nine percent nickel steel, were first introduced in the early 1940's as an economical option for storage and transportation of liquefied natural gas (Armstrong and Gagnebin, 1940). With high yield strength (85–90 ksi) and good low-temperature Toughness, these steels have been used to fabricate hundreds of on-land storage tanks and a few Kvaerner-Moss spherical LNG ship tanks (Wiersma, 1990). Prior work (Gioielli and Zettlemoyer, 2007) demonstrated that 9% nickel weldments can be safely analyzed by the usual S-N curves for carbon steel weldments when at room temperature. However, data confirming fatigue design practices at cryogenic temperature is limited. To that end, a test program was conducted at both room and cryogenic temperature and at two different stress range levels.

ABSTRACT The application of cemented soil is generally found in substrata within the deep ground, and hence, pressurized curing tests have not been regarded as very important. However, pressurized curing tests become an important research topic, from the viewpoint of design and construction, in terms of grasping the highly compressive characteristic of cemented soil in the depth direction under pressurized curing conditions which can be applied to cemented soil material in deep substrata in the future. A clarification of the difference between the compressive strength of a specimen obtained by core boring and the compressive strength of a specimen under pressurized curing conditions is necessary in order to accurately understand the compressive strength of cemented soil generated in its original state towards the direction of depth in the underground. In this research, three kinds of experiments, namely, "Non-pressurized", "Pressurized-pressure released", and "Pressurized-pressure un-released" tests, were carried out on cemented soil under pressurized curing conditions for the purpose of establishing the relationship among curing, the testing method, and the compressive strength. INTRODUCTION In general, cemented soil is used as construction material in most parts of shallow foundations, but its application in pressurized curing tests is not so prevalent.