Structural Integrity and Life Extension of Offshore Installations by Ultrasonic Peening

2011 ◽  
Author(s):  
Luis Lopez Martinez
Keyword(s):  
Structural Integrity ◽  
Life Extension ◽  
Ultrasonic Peening ◽  
Offshore Installations

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.

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.

Development of Key Performance Indicators for Offshore Structural Integrity

2008 ◽  
Author(s):  
J. V. Sharp ◽  
G. Ersdal ◽  
D. Galbraith
Keyword(s):  
Performance Indicators ◽  
Structural Integrity ◽  
Performance Standards ◽  
Key Performance Indicators ◽  
Offshore Structures ◽  
Life Extension ◽  
Offshore Installations ◽  
Incident Rate ◽  
Safety Systems ◽  
Incident Rates

Key performance indicators (KPIs) are widely used to assess performance against targets, whether these be technical, environmental or financial. Offshore KPIs are used by both duty holders and regulators to assess the reliability of equipment and systems, often they relate to safety systems and the regulator’s interest relates to such systems. The most obvious KPIs include number of fatalities, fatal accident rate, lost time injury frequency and total recordable incident rate, as well as hydrocarbon release incident rates associated with maintaining safety. Many of the “non-headline” KPIs relate to systems that could be critical in the event of an accident and these are of great importance. However KPIs have not yet been developed for the performance of the offshore structural system. Performance standards are a requirement of current UK offshore legislation, although these again are more normally associated with fire and explosion. Since many offshore installations are now in the ageing phase performance measures are increasingly important. This paper described the background to developing KPIs for offshore structures, relating to aspects which are important for both safety and asset integrity. This has been achieved based on a hazard approach, which includes extreme weather, fatigue, corrosion and accidental damage. KPI’s need to be measurable and this aspect has been incorporated in their development. It is proposed that these KPIs will have significant use in providing a basis for measuring structural performance, particularly for ageing installations where a case for life extension needs to be made.

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.

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.

A Framework for the Management of Ageing of Safety Critical Elements Offshore

2011 ◽  
Author(s):  
John V. Sharp ◽  
Edmund G. Terry ◽  
John Wintle
Keyword(s):  
Life Extension ◽  
Original Design ◽  
Safety Critical ◽  
Critical Elements ◽  
The North ◽  
Design Life ◽  
Offshore Installations ◽  
Management Processes ◽  
The North Sea ◽  
And Performance

Many offshore installations in the North Sea have now exceeded their original design life and are in a life extension phase. A Framework of six processes has been developed for the management of ageing of Safety Critical Elements (SCEs) in offshore installations. The processes include an analysis of the effect of ageing modes on SCE performance. Examples of performance indicators for typical SCEs are proposed based on how their condition and performance as may be affected by physical deterioration and other effects of ageing. Indicators for calibrating the maturity and effectiveness of the management processes are also suggested.

Ultrasound and Nonlinear Resonant Testing of Nuclear Reactor Internals Bolts

2011 ◽  
Author(s):  
S. W. Glass ◽  
B. Thigpen ◽  
J. Renshaw
Keyword(s):  
Phased Array ◽  
Nuclear Reactor ◽  
Structural Integrity ◽  
Cost Effective ◽  
Life Extension ◽  
Safe Operation ◽  
Plant Life ◽  
Nuclear Plants ◽  
Bolt Failure ◽  
Reactor Internals

As many nuclear plants approach the end of their initial 40 year license period, inspection or replacement of their reactor internals bolts must be considered. This is consistent with the Materials Reliability Program (MRP 227/228) guideline for plant life extension [1,2]. Assurance of the internals structural integrity is essential for continued safe operation of these plants. If there is no suspicion or indication of bolt failure, simple inspection is normally more cost-effective than replacement. Inspection vendors have inspected thousands of internals bolts with conventional and Phased Array UT but different head configurations and bolt capture mechanisms mandate specific qualifications for each bolt type. In some cases, complex bolt and head geometries coupled with counter-bore and locking bar interferences render classical UT inspections difficult or impossible. A range of solutions to inspect reactor internals including these difficult-to-inspect-by-conventional-UT baffle bolts has been developed by several vendors [3]. This presentation references developments to make bolt inspection a relatively quick and easy task through adaptations to the SUSI submarine inspection platform, the extensive UT qualification work suitable for conventional UT plus more recent advanced nonlinear resonant techniques to distinguish between flawed or loose, vs. acceptable bolts where conventional UT cannot be applied. Initial evaluations show that these advanced techniques may have the ability to reliably detect smaller flaws than previously possible with conventional techniques as well as provide information on bolt tightness.

Structural Integrity Management Framework for Mobile Installations

2011 ◽  
Author(s):  
A. Stacey ◽  
J. V. Sharp
Keyword(s):  
Structural Integrity ◽  
Hazard Identification ◽  
Management Policy ◽  
Audit Review ◽  
Offshore Installations ◽  
Safety Case ◽  
Integrity Management ◽  
Policy Objectives ◽  
Systems Maintenance ◽  
The Uk

This paper presents a primary integrity management (PIM) framework for mobile installations (semi-submersibles and self elevating installations) and permanently moored floating installations (FPSOs, FSUs, etc.). The primary integrity of self-elevating and floating installations depends on both the primary structure and additional systems. The framework is based upon the UK regulatory requirements for offshore installations, including the need for a thorough review of the safety case accounting for any changes in condition and future plans and verification of the primary integrity management (PIM) process. Requirements and guidance are provided for all aspects of the integrity management process covering: • primary integrity hazard identification and risk control; • resources, organisation and management, including competency assurance; • information management and documentation; • primary integrity management policy, objectives and strategy; • inspection, examination and testing; • evaluation of structure and other primary systems; • maintenance, repair and upkeep; • audit, review and continual improvement. The framework also contains guidance based on the application of existing standards and industry published documents. Finally, guidance is given on the implementation of the framework.

Parametric Investigation on the Effect Factors for Liquid Droplet Impingement Erosion

2011 ◽  
Author(s):  
Rui Li ◽  
Hisashi Ninokata ◽  
Michitsugu Mori
Keyword(s):  
Power Plants ◽  
Erosion Rate ◽  
Structural Integrity ◽  
Volume Fraction ◽  
Liquid Droplet ◽  
Droplet Velocity ◽  
Life Extension ◽  
Droplet Impingement ◽  
Pipe Surface ◽  
Bent Pipe

Liquid droplet impingement (LDI) erosion could be regarded to be one of the major causes of unexpected troubles occasionally occurred in the inner bent pipe surface. Evaluating the LDI erosion is an important topic of the thermal hydraulics and structural integrity in aging and life extension for nuclear power plants safety. In order to investigate the effect of various parameters, such as droplet diameter, droplet velocity and injected droplet number, on the erosion rate induced by LDI, droplet impingement under different conditions are conducted numerically by a two-phase computational approach. Considering the carrier turbulence kinetic energy attenuation due to the involved droplets, numerical simulations have been performed by using two-way vapor-droplet coupled system. This computational fluid model is built up by incompressible Reynolds Averaged Navier-Stoke equations using standard k-ε model and the SIMPLE algorithm, and the numerical droplet model adopts the Lagrangian approach, a general LDI erosion prediction procedure for bent pipe geometry has been performed to supplement an available CFD code. A correlation for the erosion rate in terms of droplet velocity, diameter and volume fraction is purposed for the engineers’ maintenance reference. Based on our computational results, comparison with an available accident data was made to prove that our methodology could be an appropriate way to simulate and predict the bent pipe wall thinning phenomena.

Hull Structure Integrity Management in Floating Structures–FSO Puteri Dulang Case

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Ajith Kumar Thankappan ◽  
M. Fazli B. M. Yusof
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Structural Response ◽  
Offshore Structures ◽  
Design Phase ◽  
Floating Structures ◽  
Offshore Installations ◽  
Hull Structure ◽  
Integrity Management ◽  
New Buildings

This paper highlights the key differences in practices employed in managing hull structure integrity of permanently moored floating offshore structures as against sailing vessels which are subject to periodic dry docking. During the design phase, the structural integrity management over the life of a sailing vessel is primarily taken into account by means of Class prescribed Nominal Design Corrosion Values which are added to minimum scantling requirements calculated based on strength and fatigue criteria. In contrast, for permanently moored offshore installations like FPSOs, FSOs etc. the hull structure integrity over the entire design life of the asset is a key design consideration both for new buildings and conversions. Analytic methods and tools (primarily those developed by Class Societies) are available to evaluate the strength requirements (based on yielding, buckling and ultimate strength criteria) and fatigue life of the hull structure. Typically three levels of analysis with increasing degree of complexity and analysis time are used to predict the structural response and fatigue life of the Hull during design phase. The degree of detailed analysis required needs to be determined in light of the expected optimization in terms of savings in scantlings for new building or for steel renewal requirements in case of conversions.

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