Reel Installation of 15” Clad Steel Pipeline With Direct Electrical Heating and In-Line T

The Norne Satellite project in the Norwegian Sea involved installation of a 9 km long 15” thermally insulated clad steel production pipeline. The pipeline is equipped with Direct Electrical Heating for hydrate control and an in-line T for connection of a mid-line reservoir. The installation was performed in 2005 with the reel ship “CSO Apache” after completion of comprehensive qualification programs. The Norne Satellite project represents a step forward in sub-sea pipeline technology, with the following main firsts: • Reeling of clad steel pipeline. • Direct Electrical Heating of clad steel pipeline. • Direct Electrical Heating of pipeline with in-line T. • AUT of clad steel girth welds. This paper presents experiences from the qualification and installation works.

Truss Spar Vortex Induced Motions: Benchmarking of CFD and Model Tests

Spar production systems are subject to Vortex Induced Motions (VIM) which may impact mooring and riser design. Helical strakes are employed to mitigate VIM. Model tests are typically required to validate the performance of the strakes. This paper will report on the results of benchmarking studies that have been conducted over the past few years to compare model tests with computational fluid dynamics (CFD). The paper discusses comparisons of CFD with model tests, “best practices” for the use of CFD for these classes of problems and issues related to turbulence modeling and meshing of problems at large Reynold’s numbers. This work is ongoing.

Nonlinear Dynamic Response and Buckling of Damaged Composite Pipes Under Radial Impact

In this paper, the nonlinear dynamic response and buckling of damaged composite pipes under radial impact is investigated. A model involving initial geometric deformation, delamination and sub-layer matrix damage is set up for theoretical analysis. Based on the first order shear deformation theory, the nonlinear dynamic equations of the composite pipe considering transverse shear deformation and initial geometric imperfections are obtained by Hamilton’s theory and solved by a semi-analytical finite difference method. The effects of damage on the dynamic response and buckling of composite pipes are discussed.

Fatigue Damage From High Mode Number Vortex-Induced Vibration

This paper presents results from two field experiments using long flexible cylinders, suspended vertically from surface vessels. The experiments were designed to investigate vortex-induced vibration (VIV) at higher than tenth mode in uniform and sheared flows. The results of both experiments revealed significant vibration energy at the expected Strouhal frequency (referred to in this paper as the fundamental frequency) and also at two and three times the Strouhal frequency. Although higher harmonics have been reported before, this was the first time that the contribution to fatigue damage, resulting from the third harmonic, could be estimated with some certainty. This was enabled by the direct measurement of closely spaced strain gauges in one of the experiments. In some circumstances the largest RMS stress and fatigue damage due to VIV are caused by these higher harmonics. The total fatigue damage rate including the third harmonic is shown to be up to forty times greater than the damage rate due to the vibration at the fundamental vortex-shedding frequency alone. This dramatic increase in damage rate due to the third harmonic appears to be associated with a narrow range of reduced velocities in regions of the pipe associated with significant flow-induced excitation.

Hydrodynamic Properties of an Asymmetric Deepwater Riser Bundle

The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a riser tower tensioned by a steel buoyancy tank at its top end and distributed foam buoyancy along a central structural tubular. The riser bundle is asymmetric in cross-section and this paper presents the work performed to determine the specific hydrodynamic characteristics of the design. Both basin tests and CFD analysis results are presented with discussion on some specific hydrodynamic issues: vortex-induced vibration (VIV) of the global riser tower system, VIV of individual risers, and the dynamic stability of the global system (i.e. galloping). Finally, guidelines for the assessment of the hydrodynamic behaviour of such system geometries are proposed. The results of this paper demonstrate that the Greater Plutonio riser bundle represents an effective solution in term of hydrodynamic behaviour and is not sensitive to VIV fatigue or galloping.

Three-Dimensional Numerical Simulations of Circular Cylinders Undergoing Two Degree-of-Freedom Vortex-Induced Vibrations

In an effort to gain a better understanding of the VIV phenomena, we present three-dimensional numerical simulations of VIV of circular cylinders. We consider operating conditions that correspond to high Reynolds number flow, low structural damping, and allow for two-degree of freedom motion. The numerical implementation makes use of overset (Chimera) grids, in a multiple block environment where the workload associated with the blocks is distributed among multiple processors working in parallel. The three-dimensional grids around the cylinder are allowed to undergo arbitrary motions with respect to fixed background grids, eliminating the need for tedious grid regeneration at every time step.

Submarine Pipeline Installation JIP: Strength and Deformation Capacity of Pipes Passing Over the S-Lay Vessel Stinger

The development of deep water gas fields using trunklines to carry the gas to the markets is sometime limited by the feasibility/economics of the construction phase. In particular there is a market for using S-lay vessels in water depth larger than 1000m. The S-lay feasibility depends on the applicable tension at the tensioner which is a function of water depth, stinger length and stinger curvature (for given stinger length by its curvature). This means that, without major vessel up-grading and to avoid too long stingers that are prone to damages caused by environmental loads, the application of larger stinger curvatures than presently allowed by current regulations/state of the art is needed. The work presented in this paper is a result of the project “Development of a Design Guideline for Submarine Pipeline Installation” sponsored by STATOIL and HYDRO. The technical activities are performed in co-operation by DNV, STATOIL and SNAMPROGETTI. The scope of the project is to produce a LRFD (Load Resistant Factor Design) design guideline to be used in the definition and application of design criteria for the laying phase e.g. to S and J-lay methods/equipment. The guideline covers D/t from 15 to 45 and applied strains over the overbend in excess of 0.5%. This paper addresses the failure modes relevant for combined high curvatures/strains, axial, external pressure and local forces due to roller over the stinger of an S-lay vessel and to sea bottom contacts, particularly: • Residual pipe ovality after laying, • Maximum strain and bending moment capacity. Analytical equations are proposed in accordance with DNV OS F101 philosophy and design format.

Numerical Prediction of Impact-Related Wave Loads on Ships

We present a numerical procedure to predict impact-related wave-induced (slamming) loads on ships. The procedure was applied to predict slamming loads on two ships that feature a flared bow with a pronounced bulb, hull shapes typical of modern offshore supply vessels. The procedure used a chain of seakeeping codes. First, a linear Green function panel code computed ship responses in unit amplitude regular waves. Wave frequency and wave heading were systematically varied to cover all possible combinations likely to cause slamming. Regular design waves were selected on the basis of maximum magnitudes of relative normal velocity between ship critical areas and wave, averaged over the critical areas. Second, a nonlinear strip theory seakeeping code determined ship motions under design wave conditions, thereby accounting for the ship’s forward speed, the swell-up of water in finite amplitude waves, as well as the ship’s wake that influences the wave elevation around the ship. Third, these nonlinearly computed ship motions constituted part of the input for a Reynolds-averaged Navier-Stokes equations (RANSE) code that was used to obtain slamming loads. Favourable comparison with available model test data validated the procedure and demonstrated its capability to predict slamming loads suitable for design of ship structures.

The Required Collaboration Between Universities and Government Administration in Plans for the Regeneration of Ports and Harbors That Utilize the Appeal of Marine Space

Marine space has a variety of appealing elements such as in use as resorts, for leisure, marine sports, physical distribution and the function involving the flow of people. However, ports and harbors that have lost their physical distribution functions and are steadily declining are on the increase. The Ministry of Land, Infrastructure and Transport is attempting to undertake regeneration of such ports and harbors that have lost their vitality from the middle of the 20th century. To date, regeneration plans for ports and harbors have been under the initiative of government administration but today, plans for the regeneration of ports and harbors and measures for revitalizing port towns are being reviewed in various ways including the creative development of communities through participation of the local citizenry and the convening of workshops by NPOs. As a part of this, the Chiba Port and Harbor Office in which the national government invests has begun a trial attempt to launch new projects for the invigoration of port towns through the formation of a program under which plans for the regeneration of ports and harbors and the invigoration of port towns will be undertaken through the collaboration of universities and local administrative governments. As a forerunner to such a model project, a program to form a regeneration plan for Kisarazu Port through the collaboration of Kisarazu and the Department of Oceanic Architecture & Engineering of Nihon University for senior 4th year students with the national government’s Chiba Port and Harbor Office as the moderator has been undertaken. At Nihon University, in the curriculum of Oceanic Architecture, A Planning Studio, 7 teachers and 58 students participated and 14 classes with three hours each week were conducted. This paper introduces the background to this and reports on the status of local contribution by the university.

Research Into the Extraction of the Appeal Points of Marine Space in the Okinawa Marine Resort and a Method of Estimating the Accommodated Population

In the formation of a marine resort, the extraction of the various appeal points of marine space is an important issue. For this reason, this research project targeted Kumejima in Okinawa Prefecture, Japan, and considering tourists who visit the resort as the target of the study, a decision was taken to evaluate the quality of the appeal points that comprise the resort. As a result, the appeal points of marine space were found to be comprised of three main resource elements and 13 categories related to these elements. The accurate number of tourists who visit a resort, be it marine resort or otherwise, must be grasped in order to plan the promotion of the resort and reactivation of the community. For this reason, this research project proposed a method of grasping such trends utilizing tobacco tax that is a unique system of taxation in Japan. As a result, time and cost were conserved compared to past methods and it was possible to grasp the annual number of tourists with high precision. Based on these results, it is believed that materials that indicate the direction of the formation of marine resort in Kumejima in the future have been provided.