bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study Using API RP2A-LRFD
Authors: Ferguson M.C. 
Published: October 2008

ABSTRACT
This paper assesses the benefits offered by API RP2ALRFD. With reference to the Goodwyn 'A' platform, it contrasts the requirements of the draft LRFD version of RP2A with those of the current version and those of NPD. It demonstrates that improvements in reliability offered by API RP2A-LRFD can be achieved without significant change in structure weight.

1.0 INTRODUCTION

1.1 GENERAL
The issue for industry review, just last December of a 'Load Resistance Factor Design' version of API-RP2A (Ref I) marks a major milestone in the history of the API Recommended Practice for Fixed Offshore Platforms. Since it was first issued in 1969, the working stress code RP2A (Ref 2) has become an internationally accepted standard for fixed platforms. The issue of a load resistance factor design version reflects the worldwide trend away from working stress design to reliability based methods.
This paper presents a comparative study using API RP2ALRFD. As a reliability based alternative, the load resistance factor design (LRFD) method offers a more consistent approach to platform safety than does the existing RP2A working stress design (WSD) method.
The study is directed to assessing the benefits of RP2A-LRFD. In the .context of the Woodside Goodwyn'A' platform, comparisons are drawn between RP2A-LRFD requirements and those of RP2A-WSD and the Norwegian Petroleum Directorate (NPD). The work is confined to the in-place strength of the jacket and module support frame (MSF).
The study is based on work performed for Woodside as part of the substructure design for the Goodwyn 'A' Platform. The reliability of the Goodwyn 'A' substructure has been a major focus of the design and results are presented showing the platform reserve capacity, computed using non-linear inelastic ductility analyses.

1.2 RP2A - LOAD RESISTANCE FACTOR DESIGN
One of the great merits of the existing API RP2A, now in its 18th edition, has been the way that sound engineering practices have been presented in a flexible manner such that the designer's judgment and creativity are not inhibited. This is achieved by providing a basic framework for design, accompanied by guidance on problem areas lying outside this framework. These same hallmarks apply also to the RP2ALRFD draft. Although fundamental differences exist between the WSD and LRFD versions, the two documents remain remarkably similar with the LRFD draft containing most of the carefully phrased clauses which are familiar to many practicing engineers.
LRFD however, is an improved approach to structural design which takes into account the possible uncertainties in the applied loads and component resistances. The designation 'load resistance factor design' derives from the concept of factoring both loads and resistances as opposed to the working stress design approach where only the resistance is divided by a factor of safety.
The Concepts of Added Mass and Inertia Forces and Their Use in Structural Dynamics
Authors: Jacobsen V. , Hansen E.A. 
Published: October 2008

ABSTRACT
A discussion on the concepts of added mass and inertia forces is provided combined with illustrative examples. The paper relates to submerged circular cylinders - single or in groups - only, and from an assessment of measured forces and analytical developments it is advocated that the added mass values determined from potential flow theory are adequate also for real flows. A procedure for determining the added mass coefficients for single cylinders and groups of cylinders has been developed, and results are given for 4 different configurations.

INTRODUCTION
Researchers and engineers specializing in hydrodynamics may be exposed to extensive treatments of the subjects on added mass and inertia forces, and they have the opportunity of familiarizing themselves with the underlying physics. This detailed insight and comprehension is not easily transferred to the majority of application oriented engineers, and one is often from basic courses left with the impression that the added mass and inertia forces are phenomena that basically are related to two coefficients that are interrelated by the simple expression C = C +' 1, and that the only problem is to Establish a set of applicable values for one of these coefficients, e.g. from laboratory experiments.
This paper attempts to bridge part of the gap between the two groups of professionals by addressing briefly the fundamentals on this subject and by reviewing well known experimental results from a perspective with emphasis on general physics. Results of recent analytical/ numerical developments are also presented and it is shown that the above simple relation does in fact not apply universally, as it is influenced by the geometric boundary conditions. It is argued that the experimentally derived C values presented in the literature do not provide the basis for an accurate assessment of the added mass applied in determining natural frequencies for the onset of structural vibrations.

SOME FUNDAMENTALS OF ADDED MASS AND INERTIA FORCES
By using the integrated load concept and the added mass or inertia coefficients the actual physics can be easily overlooked: In reality the added mass term reflects the integrated effect of the hydrodynamic pressures which are exerted on a body accelerating in a fluid, whereas the inertia force is the integrated pressures acting on a body exposed to an accelerating fluid. And these two forces are not identical. In fact the latter force is two times larger than the former for the free cylinder case.
In-Situ Pile Segment Model Experiments at Empire, Louisiana
Authors: Bogard J.D. , Matlock H. 
Published: October 2008

Abstract
Fourteen experiments were conducted at Empire, La. using instrumented pile simulation probes to measure lateral pressures and t-z behavior at various times and under a variety of loadings. Three of the fourteen were conducted at the same depth in parallel bore holes and enable comparisons of the effects of two diameters and two end conditions. A detailed presentation of the three sets of results leads to an improved understanding of the significant mechanisms and processes involved in the axial-load behavior of long offshore piles.

Introduction
Two types of instrumented probes have been developed to model segments of long flexible piles. The probes are instrumented to determine in situ the significant soil response parameters under a variety of static and cyclic loading conditions (Refs 1 and 2). The resulting data provide a basis for more rational and reliable axial pile design methods.
Experiments have included consideration of the effects on axial pile capacity of diameter, wall thickness, and setup or consolidation time, plus the effects of displacement and load history, and cyclic degradation.
In 1975 a series of tests on four 50-ft-long pipe piles 14 inches in diameter were performed at Empire, Louisiana for Chevron Oil Field Research Company (Refs 3 and 4). Test depths ranged from 115 to 360 ft. In April, 1984, fourteen experiments were performed with the instrumented model segment probes at the same site. Test depths ranged from 120 to 250 feet, covering the depths reported for Chevron's piles 1 and 2. Eight of the experiments were in a normally consolidated clay from 120 to 160 feet.
The locations of the borings in which the experiments were performed are shown in Fig 1. Also shown are the locations of earlier work at the site, including the original pile tests by TERA, soil borings made by McClelland Engineers, proprietary CPT and pyrometer work done by Fugro Gulf, and experiments with the PLS probe done by the Massachusetts Institute of Technology (Ref 5).

OBJECITVES
The research program was originally proposed as a fundamental study of the response of a normally consolidated clay to a pile under a variety of loading conditions, including comparisons with the Chevron pile tests.
The probes have been successfully deployed at the onshore and offshore sites of three instrumented large-scale pile load tests and at two onshore sites for which parallel large-diameter pile load test data are not available.
The scope included examination of open and plugged end conditions, effects of diameter on setup and shear transfer, degradation under one-way and two-way cyclic loading, and the effects of loading rate on shear-displacement behavior
Prevention of Upheaval Buckling of Hot Submarine Pipelines by Means of Intermittent Rock Dumping
Authors: Ellinas C.P. , Supple W.J. , Vastenholt H. 
Published: October 2008

Abstract
The extraction of oil and gas from marginal reservoirs has become feasible through the development of sub sea completions. As a consequence of the adoption of this technology, untreated oil and gas often at high temperatures is being transported from such completions to surface facilities by pipelines, which are therefore exposed to the effects of thermal expansion. Frictional restraint to such expansion causes built-up of high compressive forces which can in turn cause the pipeline to buckle. This paper reports on how such a potential problem was assessed and resolved in 1985.

INTRODUCTION
In 1985 a dual TFL 4-inch flow line system was installed in Shell Esso's Central Cormorant field in the North Sea between satellite well P5 and the Underwater Manifold Centre (UMC). The length of the flow line system is about 3km and the operating temperature is in the range 75 °C-85°C. As a result, designing these Flow lines, whilst ensuring their safe operation, meant making provisions for avoiding possible buckling due to restrained thermal expansion.
Initial analysis of the flow lines indicated that they would not remain stable in their shallow open trench, unless they were either buried deep or covered with a layer of rock. However, these options were considered unattractive. The method eventually chosen was based on allowing the flow lines to snake in a controlled manner, by securing them to the seabed with intermittent piles of rock dumped at predetermined intervals along the pipeline. The Central Cormorant P5 flow lines were taken into operation successfully and subsequent inspection of the lines has vindicated this innovative solution.
Recent developments in the North Sea have led to an initiative by several oil companies to embark on a joint research programmed on upheaval buckling [1,2]. In this context, it is considered timely that the methodology for avoiding upheaval buckling due to thermal expansion, as adopted in 1985 for the Central Cormorant P5 lines, be presented as it may be suitable for other small diameter pipeline projects.

BACKGROUND TO THE PROBLEM
For the extraction of oil from the central area of Shell Esso's Cormorant field the oil is passed through the UMC and transported by flow lines to the Cormorant 'A' platform. The UMC project is well documented in various publications, for example Reference [3]. At Cormorant 'A' the oil is treated to make it suitable for export to shore by pipelines.
If the crude were to be allowed to cool to ambient temperature, whilst being transported to Cormorant 'A' platform, wax would be deposited at a temperature below 32 °C and formation of hydrates would occur at a temperature below 15 °C. To avoid blockage of the flow lines, a thermal insulation had to be applied to these lines over their entire length to maintain temperature high and thus ensure that the above phenomena would not occur.
Design of Submarine Pipelines Against Upheaval Buckling
Authors: Palmer A.C. , Ellinas C.P. , Richards D.M. , Guijt J. 
Published: October 2008

ABSTRACT
This paper describes part of a comprehensive joint-industry project on upheaval buckling. It develops a semi empirical simplified design method and detailed design methods based on a new numerical analysis, and illustrates their application by examples. It assesses alternative design strategies, and the implications of strain-based design.

INTRODUCTION
When a pipeline is operated at a temperature and pressure higher than ambient, it will try to expand. If the line is not free to expand, the pipe will develop an axial compressive force. I£ the force exerted by the pipe on the soil exceeds the vertical restraint against uplift movement created by the pipe's submerged weight, its bending stiffness, and the resistance of the soil cover, the pipe will tend to move upward, and considerable vertical displacements may occur. The pipeline response might then be unacceptable because of excessive vertical displacement or excessive plastic yield deformation. Upheaval buckling is hence a failure mode that has to be taken into account in the design of trenched and buried pipelines.
The possibility of upheaval buckling is of increasing concern to the operators of flow lines in the North Sea and elsewhere. Their concern has been heightened by upheaval buckling incidents in the Danish and Norwegian sectors, and by the cost of protective measures such as rock dumping. Shell International Petroleum Maatschappij (SIPM) initiated a comprehensive upheaval buckling research program in 1987. In its final form, the research program included six phases:review of available models;comparative analysis;cover response, testing and modeling;numerical upheaval buckling model;analysis of alternative concepts;development of an upheaval buckling guideline. The present paper is one of a series describing the results of the programmer. It concentrates on phases 5 and 6, which were subcontracted by SIPM to a joint venture of three UK engineering companies r Andrew Palmer and Associates r Advanced Mechanics and Engineering, and Lloyds Register.
The paper is primarily concerned with the design aspects of upward buckling of buried pipelines. Unburied pipelines can buckle in a related but different mode, in which they snake sideways across the seabed. This mode too is important in practice and can play a major part in relieving the effects of axial force, but it is outside the scope of the present paper.
The paper first briefly describes the phenomenon, and puts forward a simplified method for preliminary design. It goes on to describe a conceptual design method based on the application of the UPBUCK program, and applies the methods to a design example. The paper then considers alternative strategies to resolve upheaval problems, and examines in more detail one of these strategies, a reduction in wall thickness made possible by the replacement of stress criteria on longitudinal stress with strain-based design criteria.
Jolliet: The Project
Authors: Koon J.R. , Langewis C. 
Published: October 2008

Abstract
This paper overviews the management, design, fabrication and installation of the Jolliet Project and briefly summarizes the companion Marquette Project. This work includes the Tension leg Well Platform (TLWP), the central Production Platform (CPP), 54 miles of pipeline and the GC52A drilling platform.
The TLWP is the first-ever tension leg well platform and is the world's deepest offshore production platform. The project took four years to design, fabricate and install. This paper discusses the field history, concept development, the scope of the project, and its management, design and construction.

INTRODUCTION
The Jolliet Field in the Gulf of Mexico Green canyon GC Block 184 was discovered in May of 1981 with a well drilled in 1,500 feet of water. A further six wells, over a four-and-a-half-year period, were required before development was approved in early 1986. Evolution of the development concept also occurred during this time period. The oil price crash of 1986 delayed construction but not detailed engineering of the TLWP.
Once construction work was approved in 1987, the project went into high gear, completing the drilling of twenty wells, installation of a 1,760 feet world record water depth tension leg platform, over fifty miles of pipelines, a large central production facility in 616 feet of water and commencement of well completions and oil production. This was accomplished in less than three years and nine percent below the original budget.
The projects are named after Louis Jolliet and Jacques Marquette, the 17th century French Canadian explorers of the Mississippi River.
Their spirit of exploration of the unknown is shared by the men and women who worked on these projects.
This paper overviews the history and accomplishments of the project and sets the stage for the nine other papers which comprise the Jolliet Project Special sessions.

FIEID HISTORY
Green canyon Block 184 is in the Flexure Trend on the continental slope in the Gulf of Mexico, about one hundred miles offshore central Louisiana (Figure 1). The lease was acquired by conoco, Getty and cities service oil companies as equal partners in November of 1980 for a bid of $7.aMM. It was a five-year Net Profits Share lease (NPSL) with a 100 percent capital recovery factor and a 50 percent net profit share factor.
In simplified terms, this means that no conventional royalty is paid on production from the lease. Instead, 50 percent of the net revenue of the lease is paid to the MMS after 200 percent of money invested in the lease, prior to production, has been recovered by the lessees.
Added Mass and Damping of a TLP Column Model
Authors: Chakrabarti S.K. , Hanna S.Y. 
Published: October 2008

SUMMARY
The Tension Leg Platform (TLP) typically has a very high natural frequency in vertical (heave) motion. While the wave energy is quite small near this natural period of 2 to 4 seconds, the nonlinear forces can introduce excitation at the natural frequency, giving rise to large tendon loads. This phenomenon is commonly known as " springing". The damping values of the TLP leg in the vertical direction are very important in the computation of this load. Little is known about these damping characteristics.
In order to investigate the hydrodynamic damping of a TLP, model testing of a vertical column of a typica1 TLP was performed. This test used a vertically moored cylinder to represent a TLP column at a scale of about 1:20. The mooring 1ines which restrained the cylinder were a pair of linear springs attached to the top and bottom ends of the TLP leg. The cylinder was oscillated in still water and in waves to record the decaying oscillations, and thus provided data to calculate the damping values. The cylinder was also mechanically oscillated with known sinusoidal motion, and the resulting loads were recorded.
The hydrodynamic added mass and damping coefficients of the vertical caisson covering a wide range of natural periods and wave frequencies have been presented. Results of this investigation can be readily used and applied in the design of TLP's. The use of the damping values found in this study will reduce predict ions of TLP mot i on and tendon loads. For deep water TLP applications, the associated cost savings can be significant.

INTRODUCTION
Many offshore structures that are floating and moored to the bottom of the ocean respond to waves at two different frequencies. One of these frequencies is the wave frequency while the other is the frequency corresponding to the natural frequency of the system (if it is distinct from the wave frequency). For a ship-shaped floating body, the natural frequency in surge is low so that the second peak appears at the low end of the power spectrum plot. On the other hand, for a vertically moored TLP, this frequency in heave falls at the high end of the spectrum. In both these cases, the exciting force is of second-order and, thus, proportional to the square of the wave amplitude (in regular waves). The response of the floating vessel is increased near the natural frequency due to the dynamic amplification. The resonant response of the vessel is limited by the amount of damping present in the system, The damping generally appears from two natural sources. One of them comes from the springs themselves, called
An Analysis of the Dimensions of Embedded Defects in the Welds of an Offshore Structure
Authors: Kountouris I.S. , Baker M.J. 
Published: October 2008

ABSTRACT
This is one of a series of papers describing an analysis of the occurrence, size and type of defects in the welds of the lower hull of the Hutton Tension Leg platform found during a detailed survey of the structure in the late stages of fabrication. This paper gives the results of an analysis of the dimensions of embedded defects detected and sized by ultrasonic testing, and involving the examination of approximately 27 km of weld by the method. Analysis has been undertaken of characteristics such as defect width, defect length and aspect ratio. Sufficient data were available to investigate the influence of parameters such as the type of welded joint, welding process, welding procedure and defect type on the defect dimensions. Results are given in terms of the statistical distributions of the sizes of embedded defects for different types of welded joint and types of defect, and are based on a sample of approximately 8300 defects.

INTRODUCTION
This paper describes the conclusions reached during a detailed analysis of the dimensions of embedded defects in the welds of the lower hull of the Conoco Hutton Tension Leg Platform (TLP).
The data that have been analysed are part of a large data bank compiled from the results of the non-destructive examination (NDE) of about 27 km of weld by ultrasonic testing (UT) and about 76 km of weld by magnetic particleinspection (MPI) - a total of 121,270 UT and MPI examinations. These data have provided considerable scope for analysis and a general overview of some of the results has already been published by Baker et al.1 A subsequent more detailed analysis of the frequency of occurrence of defects and the occurrence of multiple defects has been given by Kountouris and Baker.2
This paper is concerned with the distribution of the size of embedded defects and with the relative frequenty of occurrence of defects of different types. Information on the sizes of surface-breaking defects has been reported elsewhere.3 In addition, a number of detailed report a have been prepared which discuss various aspects of the analyses undertaken.4–6
Knowledge of the occurrence rate and size distributions of defects in completed structures and knowledge of the factors which influence them are useful in the planning of NDE procedures and also in the safety assessment of structures which could fail by fatigue and fracture, see e.g. Ref. 7. It must be stressed, however, that because the structural form of the Hutton TLP is radically different from that of typical jacket structures, having details more akin to those found in ships' hulls, care should be taken in extrapolating the conclusions from the TLP to other forms of offshore construction.

BRIEF DESCRIPTION OF THE STRUCTURE AND NDE HISTORY
The Hutton TLP is well known as the first tension leg structure and was installed in the North Sea in 1984, with oil production starting later than year.