Development of a Micro-Habitat Hyperbaric Welding System

2021 ◽  
Author(s):  
Earl Lee Toups ◽  
Russell James Morrison ◽  
Russell John Harper
Keyword(s):  
North Sea ◽  
Design Thinking ◽  
Structural Integrity ◽  
Fatigue Cracks ◽  
Fatigue Cracking ◽  
Life Extension ◽  
Acceptance Testing ◽  
Offshore Structure ◽  
The North ◽  
Welding System

Abstract The maturation of North Sea platform jackets coupled with high fatigue stresses, fabrication defects, extensive usage, and low-redundancy design eventually result in fatigue cracking. The high sea states in the North Sea further exacerbate the problem. If not closely monitored, fatigue cracks can propagate into and around the circumference of a brace relatively quickly—ultimately leading to brace severance. When confronted with a loss of structural integrity, operators have two options: conduct expensive subsea repairs or decommission the asset. Realising a market gap, DCN Diving has explored alternate repair strategies, leading to the development of the DCN-patent pending µ-Habitat welding system. The µ-Habitat makes it possible to respond quicker, execute subsea repairs faster and guarantee quality at a fraction of the cost of bespoke or modular habitats. Through size reduction, it is possible to reduce the fabrication, production, and handling costs of µ-Habitat. Furthermore, the smaller footprint reduces installation time while simplifying sealing and de-watering offshore, saving time and money. Using a combination of product development facilitators and process improvement methodologies, such as AGILE, SCRUM, and design thinking, reduces the preparation time, making the system incredibly responsive yet flexible. Additionally, using an experienced and dedicated project team in combination with standardised products further minimises the response time to execute a repair. A dry environment, pre-heating, in-process cleaning/grinding, and unrestricted access are fundamental to ensuring high-quality welds. In addition, prototyping, extensive function testing, and mock-ups validate the habitat design before commissioning via factory acceptance testing and mobilisation to guarantee the failsafe performance of the µ-Habitat offshore. The µ-Habitat can play a crucial role in the overall life extension strategy for any offshore structure, ultimately minimising cost, risk and production downtime associated with future subsea repairs.

Ageing of Materials

2008 ◽  
Author(s):  
Erik Ho¨rnlund ◽  
O̸ystein Sævik ◽  
Rolf H. Hinderaker ◽  
Gerhard Ersdal
Keyword(s):  
North Sea ◽  
Life Extension ◽  
Research Projects ◽  
Considerable Part ◽  
The North ◽  
The North Sea ◽  
Degradation Of Materials

A considerable part of the structures in the Norwegian part of the North Sea have passed or are close to their design lifetime. Degradation of materials will play an important role in the ageing of these structures and the evaluation of their safety. Hence, Petroleum Safety Authority Norway has initiated several research projects to investigate into the ageing of materials, and how to ensure robust materials also for life extension. The present paper gives a summary of these research projects.

Fatigue Damage Repair and Life Extension of a Floating Production Unit: The VFB Platform Revisited

2011 ◽  
Author(s):  
P. J. Haagensen ◽  
J. E. Larsen ◽  
O. T. Va˚rdal
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Fatigue Cracking ◽  
Life Extension ◽  
Conference Paper ◽  
Safe Operation ◽  
Damage Repair ◽  
Production Platform ◽  
Low Levels ◽  
Extension Program

The Veslefrikk B platform was built in 1985 as a drilling exploration unit but was converted to a production platform in 1989. After only two years in service fatigue cracks were discovered and several repairs were made. However, extensive fatigue cracking continued and a retrofitting program was planned. In addition, increased payload was necessitated by more topside equipment required for a tie-in to the Huldra field which was scheduled to start production in 2001. In 1999 the platform was temporarily decommissioned and dry-docked for a comprehensive repair and upgrading program, this was completed in approximately two months. The life extension program was described in the OMAE 2000 conference paper 2954. However, after only one more year of service new cracks were found and subsequent fatigue damage necessitated new repairs. It is noteworthy that cracking this time occurred only in areas of the structure that were left untreated in the 1999 retrofitting program due to assumed low levels of stress in those areas. The paper describes the original repair and strengthening program, and the types of subsequent fatigue damage that required new repairs. Most of the cracks occurred in the hull skin plates and caused water leakage. The objective of the recent life extension program is to ensure safe operation of the platform for a period of another 20 years.

1300 Tons Grouted Integrity Support Installation Case Study

2020 ◽  
Author(s):  
Beatriz Alonso Castro ◽  
Roland Daly ◽  
Francisco Javier Becerro ◽  
Petter Vabø
Keyword(s):  
North Sea ◽  
Structural Integrity ◽  
High Strength ◽  
Regulatory Compliance ◽  
Lessons Learned ◽  
Oil Field ◽  
The North ◽  
Future Production ◽  
Heavy Lift ◽  
The North Sea

Abstract The North sea Yme oil field was discovered in 1987, production started in 1996 and ceased after 6 years when it was considered no longer profitable to operate. In 2007 a new development was approved, being Yme the first field re-opened in the Norwegian Continental Shelf. The concept selected was a MOPUStor: comprising a jack-up unit grouted to a subsea storage tank. Due to compromised structural integrity and lack of regulatory compliance that came to light shortly after installation, the platform was required to be removed [1]. The remaining riser caisson and the future 1050 t wellhead module required a support to allow the re-use of the facilities and tap the remaining oil reserves. The innovative tubular frame support was designed as a braced unit, secured to the existing MOPUstor leg receptacles and holding a grouted clamp larger than typical offshore clamps for which design guidance in ISO is available. The existing facilities had to be modified to receive the new structure and to guide it in place within the small clearances available. The aim of this paper is to describe the solutions developed to prepare and verify the substructure for installation; to predict the dynamic behavior of a subsea heavy lift operation with small clearances around existing assets (down to 150 mm); and to place large volume high strength grouted connections, exceeding the height and thickness values from any project ever done before. In order to avoid early age degradation of the grout, a 1 mm maximum relative movement requirement was the operation design philosophy. A reliable system to stabilize the caisson, which displacements were up to 150 mm, was developed to meet the criteria during grouting and curing. In the stabilizer system design, as well as the plan for contingencies with divers to restart grouting in the event of a breakdown, the lessons learned from latest wind turbine industry practices and from the first attempt to re-develop the field using grouted connections were incorporated. Currently the substructure is secured to provide the long term integrity of the structure the next 20 years of future production in the North Sea environment.

Removal of Topside Units in a Single Lift: The Repsol Yme Field Case Study

2018 ◽  
Author(s):  
Beatriz Alonso Castro ◽  
Terje Birkenes ◽  
Huib Oosterveld
Keyword(s):  
North Sea ◽  
Ballast Water ◽  
Structural Integrity ◽  
Dry Weight ◽  
The North ◽  
Offshore Installations ◽  
Safety And Health ◽  
The North Sea ◽  
The Uk ◽  
Water Tanks

Decommissioning is an emerging sector in the UK and Norway, accounting for 2% of total industry expenditure in 2010 increasing to 8% in 2017. In accordance with existing regulations in the North Sea (OSPAR), dumping, and leaving wholly or partly in place disused offshore installations within the maritime area is prohibited. Over the next eight years, 200 platforms are expected to be removed in the North Sea. There are a number of methods to remove offshore installations: Piece small, Reverse installation and Single lift. In the Single lift approach the jacket or the topside is removed in one piece, minimizing significantly the time offshore and therefore the safety and health incidents. But the Piece Small and Reverse Installation are the most common methods and are established and secure although are time consuming and labor intensive [1]. Several potential candidates for single lift technology at varying levels of technical readiness were considered in the past. The majority of the concepts remained on the drawing board, while some were awaiting project commitment. The only that was matured further than this is the Pioneering Spirit. Yme, its first commercial lift, gave this concept the “proven” status. The Yme MOPU, owned by Repsol, was a jack-up type platform standing on three steel legs of 3.5 m diameter. The dry weight of the MOPU was approximately 13,500 t. The Yme MOPU was a challenging unit to remove mainly for three reasons: The platform motions due to the lack of stiffness in the leg support, its position in contact with the caisson wellhead platform, and the fact that the legs could not be pre-cut before the operation. The method selected to remove the platform was Single lift, using the dynamically positioned platform installation and removal vessel Pioneering Spirit. The lifting arrangement consisted of 12 lift beams combined and connected in pairs to yokes. Five specifically designed yokes were installed. The yokes connect the TLS with the MOPU. The structural integrity of each interface was assessed with FE analysis. The Ballast system was used to provide additional clearance. Pioneering Spirit has a total of eighty-seven ballast water tanks, including four so called ‘Quick Drop Ballast Water Tanks’. The removal of the MOPU was performed successfully the 22nd August 2016, after two days work offshore.

Sustainment Engineering and Residual Life Prediction of Aluminum Alloy Structure at Service Environment

2013 ◽  
Vol 661 ◽  
pp. 124-127
Author(s):  
Qian Zhang ◽  
Gang Liu ◽  
Cun Li Wu
Keyword(s):  
Aluminum Alloy ◽  
Life Prediction ◽  
Structural Integrity ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Corrosion Damage ◽  
Life Extension ◽  
Alloy Structure ◽  
Service Environment ◽  
Residual Life Prediction

The effects of service environment will cause corrosion damage and fatigue cracks to initiate and grow, compromising structural integrity of the aircraft aluminum alloy structure. To develop an effective inspection and maintenance-scheduling program that takes advantage of life extension technologies, the sustainment engineering and residual life prediction method of aging aircraft aluminum alloy structure at service environment was proposed in this article. The whole algorithm of the sustainment engineering was described and the included situations of repairs, corrosion damage and widespread fatigue damage on aircraft structures were presented. At last, combining the results of FEM calculation with the AFGROW software of crack growth analyses, the residual life of corroded aluminum alloy structure was estimated.

Life Extension Issues for Ageing Offshore Installations

2008 ◽  
Author(s):  
A. Stacey ◽  
M. Birkinshaw ◽  
J. V. Sharp
Keyword(s):  
Structural Integrity ◽  
Life Extension ◽  
Original Design ◽  
The North ◽  
Design Life ◽  
Offshore Installations ◽  
Need To Evaluate ◽  
Integrity Management ◽  
The North Sea ◽  
The Uk

With many offshore installations in the UK sector of the North Sea now reaching or being in excess of their original anticipated design life, there is a particular need to evaluate approaches to structural integrity management by offshore operators. Ageing processes can affect the structural integrity of the installation and demonstration of adequate performance beyond its original design life is thus a necessary requirement. This paper addresses the issues relevant to the life extension of ageing installations.

Environmental Assisted Cracking of High Strength Subsea Material due to CP

2019 ◽  
Author(s):  
Agnes Marie Horn ◽  
Erling Østby ◽  
Viggo Røneid ◽  
Finn Kirkemo
Keyword(s):  
Fatigue Life ◽  
North Sea ◽  
Fatigue Testing ◽  
Research Work ◽  
Design Guidelines ◽  
Life Extension ◽  
External Loading ◽  
Test Program ◽  
The North ◽  
The North Sea

Abstract Several of the offshore fields in the North Sea are approaching the end of their design life and a cost-effective solution to maximize production is to document that life extension is feasible for an asset. A trend the resent years [1] is that the BOP become larger, hence the required fatigue life increases. One way to meet the increased fatigue life and external loading is to use higher strength steel to meet the design requirements set by the operators. This has motivated research related to the fatigue performance of the base material connector material both for air and under sea water with cathodic protection (CP) [2,3,4] and possible degradation of ductility and toughness in seawater with CP. However, relevant test data for wellheads material that have been in service is not to the authors knowledge, available, nor recommendations in design guidelines related to possible material degradation to be safely applied for life extension of these assets. To better evaluate life extension of subsea wellheads, a test campaign was initiated by Equinor on a retrieved wellhead in 2015. The wellhead had been in operation since 2000 in the North Sea. The general purpose of the test program was to evaluate if the low alloy steel AISI 8630 modified material had been substantial degraded during 15 years in service compared to design material properties and the materials susceptibility to hydrogen embrittlement. The test program performed consisted of slow strain rate testing (SSRT) to document possible reduction of strength and ductility, CTOD testing to document possible reduction in toughness and S-N testing to establish the fatigue strength reduction due to seawater with CP. The outline of the paper is as follows: first a summary of the latest research and trends within wellhead fatigue and materials are discussed. Next, a detailed description of the test program is given: SSRT, toughness testing and fatigue testing are presented. Finally, recommendations and proposal for further research work are given.

Material Issues in Ageing and Life Extension

2011 ◽  
Author(s):  
Erik Ho¨rnlund ◽  
Gerhard Ersdal ◽  
Rolf H. Hinderaker ◽  
Roy Johnsen ◽  
John Sharp
Keyword(s):  
North Sea ◽  
Research Work ◽  
Life Extension ◽  
Material Degradation ◽  
The North ◽  
Design Life ◽  
The North Sea ◽  
Extension Process

A considerable number of the structures in the Norwegian part of the North Sea have passed or are close to their design life. Material degradation will play an important role in the ageing of these structures and the evaluation of their safety. An overview of research work initiated by the Petroleum Safety Authority (PSA) is presented. The paper focuses on various material aspects of ageing related to offshore facilities, the risks they represent to the integrity of a facility and how to deal with them in a life extension process. The paper presents and discusses expectations towards the industry with respect to evaluation of ageing materials in life extension.

Initiative on Structural Integrity Management of Ageing North Sea Installations

2008 ◽  
Author(s):  
A. Stacey ◽  
M. Birkinshaw
Keyword(s):  
North Sea ◽  
Structural Integrity ◽  
Health And Safety ◽  
Current Phase ◽  
Front Line ◽  
The North ◽  
Offshore Installations ◽  
Integrity Management ◽  
The North Sea ◽  
Operational Activity

With an ever-increasing population of ageing offshore installations in the North Sea, the Health and Safety Executive’s (HSE’s) Offshore Safety Division has focused its front-line operational activity in recent years on the structural integrity management process and establishing the extent of any deterioration in structural integrity. The current phase of work, the Structural Integrity Management Inspection Programme (SIMIP), is described and the findings to date are presented in this paper.

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