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The relevance of the paper is the need for removal of a large number of UXO on the Norwegian continental shelf during the installation of subsea pipelines. Numerical simulations have been used to calculate the effect of an explosion, but normally with an assumption of free explosion space where the seabed is not included. The seabed effects are simply considered by exaggerating the explosive weight with an empirical factor. This paper tries to include the seabed in the simulation by using the Coupled Eulerian-Lagrangian (CEL) method. The effects of water, soil and the TNT are approached by using the Eulerian formulation with specified Equation of status (EOS). The steel pipe is approached by shell elements in a Lagrangian scheme. The strain rate effects on steel strength and failure strain have been considered through the Cowper and Symonds equation. The coupling between Eulerian and Lagrangian formulation is done by the general contact features provided by the Abaqus Explicit solver. Three offset distances (2.5 m, 5 m and 15 m) have been simulated. The simulation results are discussed in details with respect to the water, soil, TNT and pipeline deformations respectively. Additionally, the axial force is also discussed. It is shown that the present numerical model is able to capture the main characteristics of such a complicated physical process. The influence of the seabed has been shown explicitly in all the offset distances analyzed. The empirical factor method may give over-conservative results.

This paper explores concerns regarding the design, implementation, and management of alarms in DP vessels that, while in operation, need an incredibly high level of accuracy along with high reliability and safe operations. The Human, Technological, and Organizational factors (HTO) method is primarily used as analysis tool to find weaknesses in alarm handling during DP operations. The research focuses on results collected from Dynamic Positioning Operators (DPO) and instructors. Findings from the survey are presented and compared to the results from past accidents and technical requirements from Petroleum Safety Agency Norway via YA 711. Three accidents from past are referred to picturize the findings from the survey results. Furthermore, the conclusion is given with recommendations reflecting the findings from the survey. The main findings are an urgency to establish a centralized marine accident investigation system which enforces learning and recommendation to make operations safer. In addition, the survey also suggests that prohibition of clients or limiting their access to the bridge is necessary. Manufacturers could focus on research and development of alarm prioritization, on structuring and presentation, and profiting by taking feedback from end-users to make DP operations safer.

The rapidly increasing energy demand and the inevitable negative effects on the environment caused by fossil-fuelled energy production have made renewable energy technologies increasingly important and preferred among the widely used energy sources during the last decades. Wind energy is one of the leading renewable energy technologies. Wind energy is a carbon-free, environmentally friendly and competitive technology. A step forward in production of wind energy is offshore and onshore wind turbines, with their numerous advantages. Today, the increasing energy needs make onshore and offshore wind turbine applications an increasingly widespread renewable energy source. However, with this change, challenges arise during the operation phases as being associated with the strength of the wind turbines. Potential failures must be known in advance so that they can be dealt with strongly and effectively in the design phase. Damages and failures have a negative effect on the continuation of the operation and cause material and economic impacts. In this paper, the findings from a collection of failure data are presented. The database is available on request. The novelty of this paper is to assess and analyse the damages to wind turbines onshore and offshore in order to reduce the risk of potential failures, damages and collapse of wind turbines. According to the results of these studies and analyses, the database of failures experienced is considered to represent the general failure rate in the industry. This paper brings solutions and suggestions for future studies by pointing out risks and the failure situations that wind turbines are exposed to. It can help innovative solutions with the presentation of a detailed view of risk and failure situations.

At present, most of the insurance claims in the offshore wind industry are due to cable failures where a large percentage occurs during the installation of the array and export cables. As the reliability of the cables depends on the location and installation method, it is important to map the risks involved, which can compromise the cable’s integrity in individual projects. This paper presents sensitivity analyses conducted on crucial parameters in the cable laying process, with an objective of successful installation of subsea power cables without any damages to the cable. The analyses focus on the peak tension loads with reference to key parameters as cable self-weight and laying geometry, as well as the cable deployment position on the installation vessel. Finite element analyses were conducted with both static forces and dynamic forces for irregular vessel motions, by the aid of the well-tested software OrcaFlex.

The objective of the SARex exercise, conducted north of Spitzbergen in ice-infested water in late April 2016, was to identify and explore the gaps between the functionality provided by the existing SOLAS (International Convention for Safety of Life at Sea) approved safety equipment and the functionality required by the Polar Code. The exercise was a joint collaboration between the Norwegian Coast Guard (using the Coast Guard vessel KV Svalbard as the exercise platform), experts from industry, governmental organizations and academia. The exercise scenario was to be along the lines of a “Maxim Gorkiy scenario”, where an expedition cruise ship sinks in the marginal ice zone north of the coast of Svalbard.

In this paper we will review the loss of the Kolskaya jack-up platform and 53 crew members in the Sea of Okhotsk during New Year 2011- 2012 and point to causes of the loss. Thereafter we will review the near disaster when the Kulluk rig was being towed from Alaska to the US in January 2013. Although both towing incidents could have led to disasters, the operator, Shell, was capable of rescuing all personnel and getting Kulluk off its grounding and back to a safe haven. The Kolskaya incident did, however, have a sad and tragic outcome. Both incidents happened during towing in harsh weather and we will in particular discuss the characteristics of the rigs and the concerns regarding safe towing. These include: - An evaluation of the rigs’ motion characteristics in large waves (Kulluk has particularly difficult motion characteristics in waves); - Safe tow using at least two tugs to ensure redundancy during the tow; - The need to move non-essential personnel off a rig during the tow; - Management awareness of harsh Arctic conditions. The outcome of the incidents will thereafter be discussed with an emphasis on the ability to save a rig of the Kulluk type and the loss of confidence in Russian project management in the case of Kolskaya. We will also discuss how confidence in Arctic activities could be restored. Based on the analysis, we will prepare recommendations for thorough risk analysis, in particular prior to critical tow operations. We will also highlight the responsibility of the marine staff involved in such operations and the need to strengthen their role. Of importance is the need to educate all those involved about the conditions of the physical environment. The companies’ safety programs must be updated in the case of Arctic operations with an emphasis on the need for patience and an awareness of the costs for Waiting on Weather.

Several codes are currently available for design and analysis of pressure vessels. Two of the main contributors are the American Society of Mechanical Engineers providing the ASME VIII code, Ref /4/ and the Technical Committee for standardization in Brussels providing the European Standard, Ref /2/. Methods written in bold letters will be considered in the discussion presented in this paper. The ASME VIII code, Ref /4/, contains three divisions covering different pressure ranges: Division 1: up to 200 bar (3000 psi) Division 2: in general Division 3: for pressure above 690 bar (10000 psi) In this paper the ASME division 2, Part 5, “design by analysis” will be considered. This part is also referred to in the DNV-OS-F101, Ref /3/, for offshore pressure containing components. Here different analysis methods are described, such as: Elastic Stress Analysis Limit Load Analysis Elastic Plastic Analysis The Elastic Stress Analysis method with stress categorization has been introduced to the industry for many years and has been widely used in design of pressure vessels. However, in the latest issue (2007/2010) of ASME VIII div. 2, this method is not recommended for heavy wall constructions as it might generate non-conservative analysis results. Heavy wall constructions are defined by: (R/t ≤ 4) with dimensions as illustrated in Figure 1. In the case of heavy wall constructions the Limit Load Analysis or the Elastic-plastic method shall be used. In this paper focus will be on the Elastic-plastic method while the Limit Load Analysis will not be considered. Experience from recent projects at IKM Ocean Design indicates that the industry has not been fully aware of the new analysis philosophy mentioned in the 2007 issue of ASME VIII div.2. The Elastic Stress Analysis method is still (2012) being used for heavy wall constructions. The NS-EN 13445-3; 2009, Ref /2/, provides two different methodologies for design by analysis: Direct Route Method based on stress categories. The method based on stress categories is similar to the Elastic Stress Analysis method from ASME VIII div. 2 and it will therefore not be considered in this paper.

With considerable amount of oil and gas resources, the Arctic zones are becoming more and more attractive for oil and gas exploration and production. However, to be able to produce oil and gas in this region, several new challenges have to be faced. One of these is the heavy ice condition. Thus, to face this challenge, new technologies are required. In drifting ice to heavy ice conditions, a floating stationary unit must withstand the important design ice loadings. Due to these loadings, a safe design of the vessel to seabed connection, however, cannot rely on thrusters’ utilization alone. A mooring system needs to be particularly reliable and strong. Eventually, disconnection may be needed in the event of loss of position [Gudmestad et al., 09]. With regard to these observations, it seems relevant to compute and analyze the loading in the mooring device. The vessel studied in this paper is a moderately sized mono-hull icebreaker suitable as an offloading terminal for deep or shallow water production systems or onshore facilities, as control centre for subsea facilities, as process facility with a small process plant or as an intervention vessel for subsea satellites. The Arctic Ocean has a water depth varying from tens of meters (Pechora Sea and Kara Sea as well as parts of the Beaufort Sea) to a couple of thousands meters (Canada Basin). This implies finding different mooring solutions to suit these different water depths. Due to weight limitations, it is challenging to design a mooring system for arctic deep water made of chain or wire. The partial use of polyester ropes may be an attractive alternative. Due to its particular features, the polyester rope’s behavior is not fully understood and it is needed to be further studied for use with a moored installation in this region with very large mooring forces. This paper aims at presenting the results of ice load calculations on mooring systems composed of different kinds of mooring elements (polyester ropes, wire ropes, chains and buoyant elements) and proposing different geometries according to the water depth.

This paper focuses on a comparison of sub sea and surface petroleum developments and discusses the application of sub sea developments in Arctic waters. The paper highlights the benefits of sub sea developments and compares these to the benefits of surface developments. Among important parameters to consider are the water depths at the sites and the ice conditions, as well as the regularity of the operations. Reference are given to developments on the Canadian Shelf offshore Newfoundland and to recent developments in the Barents Sea where the Snøhvit development represents the first full field sub sea development in the Arctic. The potential for extension of the Snøhvit technology to deepwater Arctic gas condensate fields is discussed. It is emphasized that the ice conditions have to be taken into account when selecting field development concepts for the Arctic offshore.

This paper focuses on marine assets for subsea intervention operations in regions with harsh environmental conditions, from field development to inspection, maintenance and repair (IMR) during the production stage of the field. Topics treated are typical environmental conditions, remoteness and distances of transportation, desired vessel functional requirements and characteristics, as well as examples of operations and discussions about vessels.

Despite the obvious economic advantages of utilising supply chains across the northern routes, there are significant challenges to their reliability. Every year an increasing number of ships venture into the region to supply, extract or transit the most northern parts of the world. However, supply chain reliability has been a significant challenge for ship operators, despite technological and organisational innovations. This paper investigates the hazards that face Arctic supply chain reliability in the region surrounding Baffin Bay and Greenland as well as the technological and organisational developments that are adopted to mitigate them. A bow-tie approach is used to illustrate the challenges faced by the shipping industry. We conclude that increased traffic will require significant investments in systems and infrastructure developments to manage Arctic hazards, thereby increasing reliability. Specifically, protective barriers like emergency response and icebreaker capacity need to be upgraded and positioned closer to emerging shipping lanes. Northwest Canada and Greenland are both poorly covered in terms of helicopter search and rescue and icebreaker availability. The consequence is that, with the increase in traffic outside the traditional busy routes in the south, supply chains lack access to effective Arctic hazard barriers.

There are substantial economic opportunities in extracting minerals in the Arctic region. However, it has proven difficult for operators to ensure reliable supply chains (SCs) north of the Arctic Circle. This paper uses a case study approach to illustrate the challenges of SCs reliability for mining projects in the northern Baffin Bay and on Greenland, discussing the technological and organisational developments that can mitigate them. A bow-tie approach shows the challenges faced by the industry and the effect of mitigating initiatives. We conclude that increased traffic will require technological, organisational and infrastructure developments to manage SC hazards and increase SC reliability. The available protective and preventive barriers have focused on avoiding periods where hazards could impact SC reliability. However, this strategy is unsustainable in the long term as a viable strategy for mining operations. It exposes the operations to Arctic hazards that are difficult to mitigate when time is limited. The consequence is that SCs often lack access to effective Arctic hazard barriers, ensuring increased SC reliability.