Assessment of Ageing Structures: Case Studies

2011 ◽  
Author(s):  
Einar Landet ◽  
Narve Oma ◽  
Gerhard Ersdal ◽  
Gudfinnur Sigurdsson ◽  
Trond So̸rensen
Keyword(s):  
Service Life ◽  
Continental Shelf ◽  
Case Studies ◽  
Structural Integrity ◽  
Life Extension ◽  
Extension Phase ◽  
Harsh Environments ◽  
Safety Level ◽  
Norwegian Continental Shelf

In all phases of the service life of a structure, uncertainties will occur, hence probability based methodologies may be an important and valuable tool in order to verify structural integrity and the corresponding expected safety level. This paper gives a brief description of an approach for how to demonstrate the safety of facilities in the life extension phase by the use of risk based inspection (RBI) plans. This is illustrated with four separate cases used for assessment and life extension of FPSOs operating in harsh environments on the Norwegian continental shelf (NCS). The assessments are partly based on the methodology introduced in NORSOK (2009).

Use of Capability Maturity Modelling to Ensure Ageing and Life Extension are Adequately Considered in Structural Integrity Management

2011 ◽  
Author(s):  
J. V. Sharp ◽  
G. Ersdal ◽  
D. Galbraith
Keyword(s):  
Continental Shelf ◽  
Structural Integrity ◽  
Life Extension ◽  
Capability Maturity ◽  
Offshore Installations ◽  
Ageing Processes ◽  
Integrity Management ◽  
Norwegian Continental Shelf

An increasing number of offshore installations are in the life extension stage of life, with ageing processes needing to be taken into account. This is particularly important for structural integrity. Capability Maturity Modelling enables the levels of maturity in processes associated with the management of ageing to be identified and improved if required. The paper describes the model and how it has been used for assessing the management of structural integrity for installations on the Norwegian Continental Shelf.

Assessment of Offshore Structures for Life Extension

2008 ◽  
Author(s):  
Gerhard Ersdal ◽  
Erik Ho¨rnlund
Keyword(s):  
Service Life ◽  
Continental Shelf ◽  
Offshore Structures ◽  
Design Methods ◽  
Life Extension ◽  
Considerable Part ◽  
Design Service Life ◽  
Extended Life ◽  
Norwegian Continental Shelf ◽  
New Facilities

A considerable part of the structures on the Norwegian continental shelf have passed or are close to the design service life. Several of these structures are planned to be used further in an extended life. In most cases, traditional analyses in accordance with design methods are used for evaluating the structures for life extension. The present regulation and standards have so far had emphasis on design of new facilities, and a need for updated regulations and standards also taking into account ageing facilities and life extension is well overdue. This paper will discuss aspects of ageing that may reduce safety of offshore facilities, maintenance needs for ageing facilities, and propose general principles of assessment of ageing facilities for life extension. The paper is a summary of the research performed by and for the Petroleum Safety Authority - Norway.

Fatigue Life Extension of Offshore Structures by Ultrasonic Peening

2011 ◽  
Author(s):  
Luis Lopez Martinez
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Fatigue Resistance ◽  
Structural Integrity ◽  
High Stress ◽  
Offshore Structures ◽  
Life Extension ◽  
Original Design ◽  
Ultrasonic Peening ◽  
Offshore Installations

The service life of offshore installations is limited by its structural integrity. Furthermore the structural integrity is mainly governed by the fatigue resistance of critical welded details. In a FPSO installation these details are among others pallet stools weld joints to deck structure and bulkheads/web frames weld connections to longitudinal in ballast tanks. ultrasonic peening can improve the fatigue resistance of welded joints. Fatigue test results shows an increase of four times for high stress ranges and up to ten times for high cycle fatigue. For specimens which have already consumed half of their fatigue life the treatment resets the clock to zero, as a minimum value. Consequently ultrasonic peening treatment was applied to several offshore installations on fatigue sensitive weld connections with the objective to extend the service life of the these. Finite Element Analysis carried out by classification societies for these offshore structures demonstrated critical fatigue lives for several weld connections. These weld connections were then treated by ultrasonic peening with the objective to extend their fatigue lives and by doing that reach the targeted service life for the installation. The successful application of the ultrasonic peening treatment was a pioneering work which involved several partners. A pilot project on a FPSO started in 2005 and the treated critical weld connections are still intact and show not sign of crack initiation despite the fact the calculations then showed shorter fatigue lives than the life span already consumed. As a result the same ultrasonic peening procedure has been proposed to be applied for other fatigue sensitive locations on the installation. Offshore installations around the world are reaching their original design life. Most of the operators chose to extend the service life of their assets rather than scrape them and build new. The reasons for that are: improved oil recovering techniques, time required to get a new build installation on site, environment concerns, wiser management of energy and resources among others. Therefore the Life Extension of Offshore Installations is a subject of current interest for the upstream industry.

State of Art in Life Extension of Existing Offshore Structures

2012 ◽  
Author(s):  
Abe Nezamian ◽  
Robert J. Nicolson ◽  
Dorel Iosif
Keyword(s):  
Structural Integrity ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Life Extension ◽  
Operational Environment ◽  
Original Design ◽  
Safety Level ◽  
Operational Conditions ◽  
Offshore Installations ◽  
State Of Art

A large number of the old oil and gas facilities have reached or exceeded their initial design life. With a continued requirement to produce oil or gas, either from the original fields or as a base for neighbouring subsea completions, many of these respective offshore installations are likely to remain operational for a period of time in the foreseeable future. The ageing offshore infrastructure presents a constant and growing challenge. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. In order to ensure technical and operational integrity of these ageing facilities, the fitness for service of these offshore structures should be maintained. The maintenance of structural integrity is a significant consideration in the safety management and life extension of offshore installations. Detailed integrity assessments are needed to demonstrate that there is sufficient technical, operational and organisational integrity to continue safe operation throughout a life extension. Information on history, characteristic data, condition data and inspection results are required to assess the current state and to predict the future state of the facility and the possible life extension. This paper presents state of art practices in life extension of existing offshore structures and an overview of various aspects of ageing related to offshore facilities, represented risk to the integrity of a facility and the required procedures and re assessment criteria for deciding on life extension. This paper also provides an overall view in the structural requirements, justifications and calibrations of the original design for the life extension to maintain the safety level by means of a maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results.

Four case studies for vertical time domain CSEM from the Norwegian Continental Shelf

2014 ◽  
Author(s):  
Stefan L. Helwig* ◽  
Abdul Kaffas ◽  
Terje Holten ◽  
Øyvind Frafjord ◽  
Kjetil Eide
Keyword(s):  
Continental Shelf ◽  
Case Studies ◽  
Time Domain ◽  
Norwegian Continental Shelf

Issues for Consideration in Life Extension and Managing Ageing Facilities

2011 ◽  
Author(s):  
Solfrid Ha˚brekke ◽  
Lars Bodsberg ◽  
Per Hokstad ◽  
Gerhard Ersdal
Keyword(s):  
Oil And Gas ◽  
Point Of View ◽  
Life Extension ◽  
Original Design ◽  
Material Degradation ◽  
Safety Level ◽  
Design Life ◽  
Extended Operation ◽  
Norwegian Continental Shelf ◽  
Extension Process

A large number of facilities and parts of the infrastructure on the Norwegian Continental Shelf are approaching or have exceeded their original design life. Many fields, however, have remaining recoverable oil and gas reserves which may be profitable if the field’s life is extended. From a safety point of view, the condition of systems, structures and components may not be acceptable for extended operation. Ageing and life extension have been a top priority for the Petroleum Safety Authority Norway (PSA) and PSA has asked SINTEF to conduct a study of various aspects of ageing and life extension. The paper presents main results from the study, including how to document the safety of an ageing facility and how to uphold the safety level by means of a maintenance programme balancing three aspects of ageing: 1) Material degradation, 2) Obsolescence, i.e. operations and technology being “out of date” and 3) Organisational issues. The paper presents six main steps of the life extension process and discusses important issues to consider for operators in a life extension process.

scholarly journals Structure Life Extension towards the Structural Integrity of Sukhoi Su-30MKM

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5562
Author(s):  
Arvinthan Venugopal ◽  
Roslina Mohammad ◽  
Md Fuad Shah Koslan ◽  
Ashaari Shafie ◽  
Alizarin Ali ◽  
...  
Keyword(s):  
Service Life ◽  
Structural Integrity ◽  
Simulation Analysis ◽  
Fatigue Loading ◽  
Operating Conditions ◽  
Life Assessment ◽  
Life Extension ◽  
Destructive Testing ◽  
Fighter Aircraft ◽  
Service Life Extension

The airframe structures of most fighter aircraft in the Royal Malaysian Airforce have been in service for 10 to 20 years. The effect of fatigue loading, operating conditions, and environmental degradation has led to the structural integrity of the airframe being assessed for its airworthiness. Various NDT methods were used to determine the current condition of the aircraft structure after operation of beyond 10 years, and their outcomes are summarized. In addition, although there are six critical locations, the wing root was chosen since it has the highest possibility of fatigue failure. It was further analyzed using simulation analysis for fatigue life. This contributes to the development of the maintenance task card and ultimately assists in extending the service life of the fighter aircraft. Using the concept of either safe life or damage tolerance as its fatigue design philosophy, the RMAF has adopted the Aircraft Structural Integrity Program (ASIP) to monitor the structural integrity of its fighter aircraft. With the current budget constraints and structural life extension requirements, the RMAF has embarked on the non-destructive testing method and engineering analysis. The research outcome will enhance the ASIP for other aircraft platforms in the RMAF fleet for its structure life assessment or service life extension program.

Protection of Caprock Integrity for Large-Scale CO2 Storage on the Norwegian Continental Shelf

2019 ◽  
Author(s):  
Sarah Gasda ◽  
Ivar Aavatsmark ◽  
Bahman Bohloli ◽  
Helge Hellevang ◽  
Jan Nordbotten ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Large Scale ◽  
Co2 Storage ◽  
Caprock Integrity ◽  
Norwegian Continental Shelf
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