Search our collections

European Pipeline Research Group (EPRG) has produced a set of recommendations on defects in transmission pipeline girth welds. The background to the approach is presented in which the concept of ductile to brittle fracture transition is studied and the way it changes from laboratory specimens to real structures is considered. A simplified approach requiring minimum toughness value and predicting the failure load by plastic collapse analysis was used. Use of the design curve concept is strongly present in pipeline girth welding standards.

The reefs within Diego Suarez Bay in northern Madagascar are influenced by anthropogenic stresses including eutrophication overfishing and sedimentation. In regions subject to such stresses bleaching is often high with low rates of coral recovery. Thus the extent to which these corals are able to survive and recover will be dependant on the magnitude of these external factors. This paper presents the findings of a study into health of reefs in Diego Suarez Bay Suarez followng the 2005- bleaching event and compares the recovery of corals subjected to varying levels and types of physical and anthropogenic stress. The extent of the bleaching and recovery of corals across five study sites were assessed relative to both coral community structure and biophysical fluctuations.

The Minerals Management Service (MMS) currently supports API and Offshore Operators Committee (OOC) that compliance with RP 75 should be voluntary rather than regulatory but after two years MMS will review the situation and decide whether to continue with voluntary implementation or introduce regulations. MMS API and OOC have developed an API RP 75 implementation status assessment process which is described and discussed. These assessments will be performed annually starting with the January-February 1995 assessment. Continued voluntary implementation of RP 75 will depend on the number of companies choosing to adopt RP 75 and how fast these companies are progressing towards total implementation of RP 75.

This work treats the problem of assisted dynamic positioning (DP) of moored FPSOs focusing on robustness issues regarding the modeling of hydrodynamic current forces and moment. Sliding Mode Controllers (SMC) with an alternative compensation technique have quite recently been investigated and proved to be an appropriate choice. The present work shows simulations of the SMC technique (with the simpler Short Wing Current Model) controlling a tanker that is otherwise modeled with a 'Hydrodynamic Derivative Model'. The results confirm that for control purposes the 'Short Wing-Cross Flow Current Model' can be used since performance and stability requirements are preserved.

One of the most complicated and time-consuming processes in ship production is determining the optimum route for piping. In the past research has primarily focused on the use of deterministic or only non-deterministic optimisation techniques to find the optimal route. DelftPipe an automatic system to generate optimum collision-free routes for pipes is presented. A deterministic technique is used as a tool to find the optimum route while the tools parameters are chosen by a non-deterministic technique. The practical aspects such as branching and minimising the cost are included in the objective function to be optimised. The performance of this novel approach is measured by its ability to accommodate and efficiently solve problems in the real ship application. The main architecture of the system is explained. The Interface Module of the system is also described in more detail. The Engine Module of the system is discussed its components are described as well as how each component works. A list of variables that should be optimised by the Optimiser Module of the system is also given. Test case results are then shown and discussed and conclusions drawn.

A series of articles on auxiliary power discusses how shaft generators benefit from advanced electronics the need for greater electrical power security and dedicated genset prime movers. AVK's Concycle shaft generator system comprises a main generator a converter and a converter-generator and is a self-contained functional unit requiring no external converter or reactive power machine. Siemens has also developed a new shaft generator system. Emergency electrical power is now generally secured by a dedicated diesel genset which is self-contained and works in complete isolation from the main electricity source. Use of uninterruptable power supplies (UPS) is also discussed. All the engines produced by MAN B&W Diesel's Holeby division in Denmark are intended for auxiliary power generation. The growing market for gas-diesel gensets for floating production and storage (FPSO) vessels is being addressed by Wartsila Diesel while Krupp MaK Volvo Penta and Cummins are also active in this area.

The paper presents the results of a programme designed to define the material stress and environmental factors controlling sensitivity of ferritic-austenitic stainless steels to hydrogen embrittlement stress cracking when exposed to cathodic protection. Factors examined in small and large-scale tests include microstructural coarseness phase balance and hardness of a range of parent steels and welds. The results are presented in terms of threshold strain and normalised stress to develop hydrogen embrittlement stress cracks. The effects of microstructure and applied potential on crack initiation and propagation are described. Recommendations are made with respect to the strain/normalised stress levels for ferritic-austenitic steels under cathodic protection.

The regulatory environment and various methods for ballast water management are briefly reviewed. Several technologies that could be used for on board treatment of ballast water are examined. Particular attention is paid to the treatment of ballast water using a solids separation primary treatment and UV light secondary treatment system. The installation of an OptiMar Ballast Treatment system aboard the cruise ship 'Regal Princess' is discussed. The results of testing of the system both prior to and after the full-scale shipboard installation are presented. Lessons learned from the 'Regal Princess' and other testing are discussed.

The problems associated with the invasion of NIS (non-indigenous species) or ANS (aquatic nuisance species) into marine ecosystems worldwide are immense. Ballast water is generally considered to be the prime means for the translocation of marine organisms although there are certainly other means such as hull fouling. The regulatory environment and various methods for ballast water management are reviewed. The several technologies that could be used for on board treatment of ballast water are examined. Particular attention is paid to the treatment of ballast water using a solids separation primary treatment and UV light secondary treatment system. The installation of an OptiMar Ballast Treatment system aboard the cruise ship 'Regal Princess' is discussed. The results of testing the system both prior to and after the full-scale shipboard installation are presented. Lessons learned from the 'Regal Princess' and other testing are discussed.

This guide makes recommendations for safety and pollution prevention features of the design, equipment, operation and management of all vessels used for the carriage of petroleum or chemical cargoes in bulk, and of associated towing/pushing vessels, which are not covered by international conventions. It has chapters on certification and documentation; crew management; navigation, communications and electronics; safety management; pollution prevention; structural condition and general appearance; cargo and ballast systems; mooring and anchoring; towing - equipment and procedures; engine room and steering gear; vessel to vessel transfer; chemical barge supplement; and gas barge supplement.

This book endeavours to show how the problems of battery control have been solved in many industries. It will act as a guide in assisting engineers to solve new battery problems as they arise. The work contains a description of the fundamental principles of battery charging, then explains how these principles are used in various specialised applications. Each chapter has a brief historical introduction to show the lines on which the development has taken place, and this is followed by a description of present-day practice. Subjects covered include the development of batteries; their construction and chemistry; charging from DC or AC mains; applications in electric vehicles, for emergency lighting and power, in power stations, telephone exchanges, the marine, railway and mining industries, in road vehicles and in aircraft and in isolated electric generating plants.

Close study of the Baydaratskaya Bay climate conditions has begun with the Baydaratskaya Bay Pipeline Crossing Project development. The presented paper might be classified as a long-term case study. Its goal is to show the present climate conditions of the Baydaratskaya Bay on the background of the climate conditions which have been observed since 1930s. The main attention is paid to seasonal contributions into interannual variability and advective climate-forming factors. 1934-1998 monthly mean temperature 1942-1998 ice-free season duration and 1977-1995 wind- direction data are analysed. It is shown that long-term temperature background is defined with winter conditions. Prevailing winter westerlies lead to positive winter and annual temperature anomaly and to the increase of ice-free season duration; the summer temperature has significant relationship neither with annual temperature nor with prevailing wind direction.

Coastal protection works in the Inner Danish Waters tend to be assessed at a regional scale. By making overall plans for coastal protection works it is possible to restore beaches by using beach nourishment which can stop shoreline retreat and at the same time increase the recreational value of the beach. Detached breakwaters can extend the life of nourished sand but in some cases the long-shore sediment transport will eventually result in the loss of sediment necessitating maintenance nourishment. Three beach nourishment projects carried out in the Inner Danish Waters during the past five years are described. These projects shown examples of coastal protection projects involving small-scale beach nourishment and minimising the use of coastal structures which are the trends pursued by the Danish Coastal Directorate. For each project a brief description of site conditions before initiations of the project is made together with a presentation of the main hydraulic and morphological conditions. The methods used in the design are outlined followed by comments related to the construction. Finally the project experiences are presented based on site inspections aerial photos and monitoring programmes.

Passive underwater detection and tracking sonar systems using autonomous underwater vehicles (AUVs) have many important applications. Because of imperfections in vehicle control it is common for an AUV to undergo significant yaw and pitch oscillations. As a result it is important to compensate for the vehicle motion when generating true bearing estimates while using a rigidly attached acoustic line array. This paper describes full beam interpolation tracker and bearing stabilization algorithms that were implemented to address these issues on an intelligent AUV sonar sensor and tested during a subsequent sea trial with the goal of providing target bearing estimates to a target track estimation algorithm. These beam tracking and bearing stabilization algorithms can also be applied to the case of a flexible towed array with some additional modifications. Initial results indicate that this is an effective method of measuring stabilized true target bearings.

Passive underwater detection and tracking sonar systems using autonomous underwater vehicles (AUVs) have many important applications. Because of imperfections in vehicle control it is common for an AUV to undergo significant yaw and pitch oscillations. As a result it is important to compensate for the vehicle motion when generating true bearing estimates while using a rigidly attached acoustic line array. This paper describes full beam interpolation tracker and bearing stabilization algorithms that were implemented to address these issues on an intelligent AUV sonar sensor and tested during a subsequent sea trial with the goal of providing target bearing estimates to a target track estimation algorithm. These beam tracking and bearing stabilization algorithms can also be applied to the case of a flexible towed array with some additional modifications. Initial results indicate that this is an effective method of measuring stabilized true target bearings.

This paper describes the drag coefficient and the inertia coefficient on rigid circular cylinders under oscillating flows. Also vortex-induced vibration (VIV) behaviour of tubing is investigated by using horizontal orbit patterns of test models including effect of VIV. Rigid circular cylinders are used for the model experiment. The test models are suspended into still water through a flat spring and hence VIV is observed found with hydroelasticity in spite of a rigid circular cylinder. This is a forced oscillation test in still water. Model tests of forced oscillation are carried out under transverse motion fixed conditions because VIV effects are investigated to the drag and the inertia coefficients. It is shown that the drag coefficient increases and the inertia coefficient decreases when larger VIV response occurs under forced oscillation in an inline direction.

Large bending moments may develop on free pipeline lengths in the proximity of pipe sections subject to a local force. Sometimes the local force is such as to cause a partial loss of the sectional strength capacity of the pipe. In such conditions the limit bending capacity of the pipe section subject to local load effects is significantly influenced. This aspect is not covered by international design codes and the scope of this paper is to show that in some circumstances it must be taken into due account. In this paper the relevant literature as concerns experimental tests interpretative models analysis methodologies and design approaches is reviewed. The FE model and post-processing purpose-developed to investigate the interaction between local and global effect are discussed. The findings of FE analyses in particular the effect of load combination load history pipe geometric characteristics and loading - magnitude and shape of the contact area are presented.

Complex deepwater developments require planning and insight that was not required for the shallow water installations in the past. The deeper the water the more the engineer is required to think three dimensionally. Model simulation has evolved to the stage that it is now being used with a high degree of accuracy three dimensionally. It provides a complete picture of projects for the engineer and clients and helps them to understand the clashing between the various offshore production systems. When considering a deepwater moored structure the entire footprint covers a vast area and usually consists of 12-14 mooring lines. Through this maze there can be as many as 20-30 lines servicing the production area. On top of this pipelines are required to traverse this area. The technique of manoeuvring amongst this mess is called 'keelhauling'. During the modelling phase vessel operators riggers and field engineers obtain a valuable understanding of the 3D aspects of working among pipelines manifolds risers and mooring lines safely. In face the riggers use this as a tool for establishing their cable requirements pendant lengths and spooling capacities for a safe operation. The latest modelling has incor100241

The Hammerfest LNG plant on the island of Melkoya Norway is being constructed to liquify gas from the Snohvit gas field in the Barents Sea for export by LNG/LPG vessels. The initial design for a dynamically stable breakwater to protect the site was changed to that of a statically stable Icelandic-type berm. The final design for the Melkoya breakwater was for a breakwater capable of withstanding a significant wave height up to 7.5 m with armourstones up to 35 tonnes at the most exposed locations and to be statically stable and non-reshaping for the 100-year storm event. It should also be able to withstand a wave height of the 1000-year return period without total damage.

The Japan/East Sea (JES) contains several oceanic regions separated by dynamic boundaries. These distinct regions and the physical features that establish and maintain the boundaries between the regions have significant impacts on its ocean biology. The central basin of the JES contains two primary biogeographic regions defined by the dominant currents and hydrographic structures. The region is bisected by the Subpolar Front (SPF) and its associated mesoscale circulation. In this paper selected findings are described from the JES biological sampling program specifically targeted at identifying the role of dynamic physical boundaries such as the SPF in structuring the ecosystem. After some introductory information a look is taken at the bio-optical time series. Next consideration is given to variations in primary production followed by fluorescence seasonality across the SPF and zooplankton distributions/SPF.