Structural Integrity Management, Ageing and Life … Integrity Management, Ageing and Life Extension...
Transcript of Structural Integrity Management, Ageing and Life … Integrity Management, Ageing and Life Extension...
Structural Integrity Management, Ageing and
Life Extension
John Sharp, Ocean Structures and Cranfield University
for PSA seminar on “Structural Integrity Management for Ageing and Life
Extension” – April 2010
Topics
• Background to Structural Integrity Management (SIM)– Design life, life extension– Assessment process
• Capability maturity modelling• Questionnaire – objectives and content• Selected topics (responses)
– Key performance indicators– Awareness of ageing– Competency– Emergency planning
• Conclusions
SIM (ISO 19902)
•SIM is a structured method recommended for assessing the condition of a structure•It is a cyclic activity covering data collection, data evaluation, development of an inspection strategy, development and execution of an inspection programme and any consequent remedial works
From API RP SIM
Initiators include: Life extension, damage to the installation, modifications etc
Design Life & Life Extension• The design life is the assumed period for
which a structure is to be used for its intended purpose, with anticipated maintenance, but without substantial additional maintenanceand repair from ageing processes being necessary
• Life Extension: This is defined as thecontinued operation of an installation beyond the design life assumed at the time of design or revised following reassessment.
Life Extension• UKCS: The revised Safety Case Regulations
introduced in 2005 require a revision of the safety case (regulation 14) when there is a “material change” which includes “an extension of the use of an installation beyond its original design life”.
• NCS: Information Duty Regs Requirement on consent to certain petroleum activities: The operator must obtain consent when plans exist for use of a facility exceeding the life span and the assumptions on which approval of the plan for development and operation of petroleum deposits and the plan to install and to operate facilities for transport and utilisation of petroleum is based,
•
Assessment Process
• A systematic structural assessment of a facility takes into account any changes in the physical condition that the facility has so far experienced due to ageing or accidental damage.
• It should also be undertaken using current codes and standards; the original design may have been based on earlier versions of these codes and standards.
Assessment
• Procedures for assessment have only been developed fairly recently– Post hurricane – Gulf of Mexico– Operational phase & life extension
• They are part of : – ISO 19902 section 25 (2007)– NORSOK N-006 (2009)– API RP SIM (2007 draft)
NORSOK – N-006Assessment of structural integrity for
existingoffshore load-bearing structures
• Sections:– Normative and informative reference– Terms, definitions, abbreviations and symbols– Assessment process– Data collection– Assessment principles for existing structures– Check of fatigue limit states (FLS) including
acceptance criteria– Check of ultimate limit states (ULS) and
accidental limit states (ALS)– Requirements to in-service inspection after
assessment– Documentation of structural assessment
NORSOK – N-006Life extension
• The assessment for life extension shall conclude on a safe life extension period with respect to technical and operational integrity of the facility.
• The assessment shall further identify the circumstances that will limit the life of the facility without major repairs or modifications, and specify criteria defining safe operation (e.g.permissible cracks lengths, permissible corrosion or remaining thickness, remaining anodes, degrading of paint protection, subsidence, deteriorating compounds (such as H2S, stagnant water), changed load conditions, deteriorated mechanical outfitting),including appropriate factors of safety.
Assessment of Structural Integrity – ISO 19902
The main elements in the process of initiating and conducting an assessment of a structure are:
a) assemble data on the structure, its history and exposure level;
b) determine if any assessment initiators are triggered,
c) determine acceptance criteria, d) assess the condition of the structure, e) assess the actions, f) screen the structure in comparison with similar
structures, g) perform a resistance assessment, using:
• design level analysis• ultimate strength level analysis• prevention and mitigation,
Assessment – Acceptance Criteria
• NORSOK N-006 – Fatigue Limit State• Fatigue crack growth
• ISO 19902 - Ultimate limit state• utilizations less than or equal to unity• RSR value of 1.85 or greater
• ISO 19902 – Fatigue• fatigue lives of all members and joints are at least equal
to the total design service life, and the inspection history shows no fatigue cracks or unexplained damage.
• Where fatigue lives of any members and joints are calculated to be less than the total design service life of the structure and fatigue damage has been identified, the structure may be assumed to be fit-for-purpose providing conservative fracture mechanics predictions of fatigue crack growth demonstrate adequate future life and periodic inspection monitors crack growth of the members or joints concerned.
Capability Maturity Model• A Capability Maturity Model (CMM)
concentrates on three key issues, which are:• the processes the CMM model identifies as
present in managing an activity in a successful organisation;
• the components which influence the quality of that activity;
• how organisational performance scores are established for those components .
Capability Maturity Model levels – 1 to 3
1. Basic (learner)
Processes absent or ad-hoc with no real understanding.
2. Localised (repeatable)
Processes organised & controlled at local level, no
proper procedures in place.
3. Defined (standardised)
Written procedures available across organisation. An
understanding of basic requirements but little use made
of feedback.
Capability Maturity Model levels – 4 & 5
4. Managed
Organisation has understanding of setting targets from
experience plus R&D. Processes adapted and
performance improved in response to observed failures.
5. Optimised
Organisation has good understanding of continuous
improvement. Communications and learning optimised
across whole organisation. Training and appropriate
competence are optimised.
Development of Capability Maturity Models
Previous Offshore Models1. Offshore Design Safety (DCMM) (for HSE)2. Sub-sea Reliability (RCMM) (for BP)3. Offshore Asset Maintenance (C4M) for Energy
Institute
ISO 9004 (2000) also uses five maturity stages for quality management
Organisation
8.1 Allocation & management of
resources
Repair & mitigate
S2.2Plan and undertake remedial actions
S2.1Determine repair and mitigation measures
Life extensionS3b
Particular issues for ageing of
mobile units – Classed
installations only
S3aManage life extension approval process –production installations
only
Emergency preparedness
S4.1Awareness of potential emergency situations
S4.2Understand significance of potential emergency situations
S4.3Prepare for
potential emergency situations
Assessment
S1.1In-place structural
assessment
S1.2Fatigue
assessment
S1.3Assessment
of robustness
(redundancy, tolerance to
damage)
Documents9.1
Develop DFI resume
9.2In-service
history
Analyses
6.1Evaluate,
analyse and assess
inspection data
Reporting
5.2Manage SIM
data
5.1Reporting on inspections
Supervision11.1QA/QC
11.2Independent verification
Improvements
7.1Evaluate
efficacy of inspection
programme
Resources
Goals & Req.
1.1Develop and update SIM Philosophy
Planning
3.1Inspection planning
Execution
4.1Inspection execution
Maintenance Prog.2.1
Evaluate design,
inspection data and analyses including ageing
2.2Define Long
term inspection
programme
Tech. condition
TechnicalCondition & Report
10.1Assure integrity
10.2Compare with
KPIs
10.3Management
reporting
Inputs Outputs
Main Processes (1)• Goals & requirements (Develop and update SIM
philosophy)• Maintenance programme (Evaluate design,
inspection data and analyses including ageing; Define long term inspection programme)
• Inspection planning• Inspection execution• Reporting (Manage SIM data; reporting on
inspections)
Main Processes (2)• Analyses (Evaluate, analyse and assess
inspection data)• Improvements (Evaluate efficacy of inspection
programme)• Organisation( Allocation & management of
resources)• Documents (Develop DFI Resume; In-service
history)• Technical Condition & report (Assure integrity;
compare with KPIs; Management reporting)• Supervision (QA/QC; Independent verification)
Sub-Processes• Assessment
o In-place structural assessmento Fatigue assessmento Assessment of robustness
• Repair & Mitigationo Determine repair and mitigation measureso Planning and undertaking remedial actions
• Life extensiono Managing the life extension approval process (fixed installations)o Particular issues for ageing mobile units
• Emergency preparednesso Awareness of potential emergency situationso Understanding the significance of [potential emergency situationso Preparation for potential emergency situations
Objectives of Questionnaire
• Key purpose:– Evaluate operators and rig owners on structural
integrity management– Assess operators’ approaches to life extension
requirements and to emergency preparedness– Document best of current practice– Identify gaps between operators’ practices and
PSA expectations– Identify any improvements required– Approach based on CMM model
Basis for Questionnaire• 1.1 Goals & Regulations (9)• 2.1 Maintenance programme (5)• 2.2 Definition of long term platform specific inspection programme (4)• 3.1 Inspection planning (5)• 4.1 Execution of inspection• 5.1 Reporting on inspections (3)• 5.2 Management of SIM data (4)• 6.1 (Evaluation, analysis & assessment of inspection data (6)• 7.1 Evaluation of effectiveness of inspection programme (2)• 8.1 Allocation & management of resources (3)• 9.1 Development of DFI resume• 9.2 In-service history (4)• 10.1 Assurance of integrity (4)• 10.2 Compare with KPIs (2)• 10.3 Management reporting (3)• 11.1 QA/QC (4)• 11.2 Independent verification (3)• & sub-processes
Basis of Questionnaire
• Who undertakes process• How is it managed?• How is it reported• How often updated• Is training given?
Responses to Questionnaires
• Completed questionnaires received from six duty-holders:
• Letters sent asking for clarification of responses
• Interviews held 16-20th November in Stavanger
• Presentations from each operator plus hard copy
• Report prepared on individual responses to questionnaire and from audits
• Comparison of responses
Responses to Questionnaires• Maturity levels designated for each main
process• Levels vary from 1 to 4• Most duty-holders had good general
management systems for SIM• Weakest:
– Comparison with KPIs– Independent verification & QA/QC– Understanding ageing (including competency)– Awareness of potential emergency situations
• Strongest:– Allocation & management of resources
10.2 –compare with KPIs, 11.1 – QA/QC, 11.2 – Verification,
S4.1 –S4.3 Emergency preparedness
Development of Good Practice
• Developed for key processes from levels 3 and 4 in SI- CMM model
• To be compared with good practice from operators’ responses
• Develop KPIs
Key Performance Indicators
• KPIs are quantifiable measurements, agreed to beforehand, that reflect the critical success factors (of for example a project.).
• An important requirement is that a KPI must be specific, measurable, achievable, reliable, and time dependant (SMART).
• Can be used to define the state of an offshore structure and changes in KPIs can take account of ageing processes
Use of KPIs (typical) from Questionnaires
• No. of overdue inspection work orders • Inspection done by competent personnel • No. of repairs vs scheduled repairs • No. of critical inspections overdue more than
90 days • Percentage of planned inspection program
completed• KPI’s are defined and measured as a part of
the barrier verification system where structural integrity is one of the barriers
[most do not relate to state of structure]
Key Performance Indicators
• Previous work (OMAE 2008) has developed a set of KPIs for structural integrity of offshore structures which relate 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
“Development of Key Performance Indicators for Offshore Structural Integrity”, J.V.Sharp, G.Ersdal, D.Galbraith, OMAE Conference, Portugal, 2008, OMAE2008 57203.
Key Performance Indicators
• 20 KPIs proposed.– Corrosion (4 )– Fatigue (5)– Extreme weather (2)– Structural capacity/redundancy (2) – Change of use
• 10 relate to original design process• 8 relate to detailed in-service inspection• Some hazards difficult to define suitable KPIs
– Geological/geotechnical hazards– Accidental hazards – Fire and blast
Development of KPIs –proposed
• Condition survey programme (not updated, not executed, not registered)
• Configuration survey programme (not updated, not executed, not registered)
• ULS, ALS,FLS,SLS, RSR,DSR analyses not updated
• Configuration anomalies not mitigated• Configuration changes not mitigated• Subsidence mitigation plan not established or
not implemented. • Max. subsidence level not established
Awareness of Ageing –requirement
• Need to be aware of ageing mechanisms• Need to predict future degradation including
wide spread degradation and the consequences from this degradation.
• Requirement to plan inspections and maintenance taking that degradation into account
• Consider potential interaction between ageing mechanisms
• Consider implications of uninspectable areas, their expected state and consequences of failure
Awareness of Ageing –Responses to Questionnaires• Ageing mechanisms included were:
– Corrosion (all)– Fatigue (all)– Painting/ PFP breakdown– Other mechanisms:
• Foundation settlement• Scour• Subsidence• Marine Growth• Cathodic protection system
• A more rigorous assessment would have been useful, including interaction between mechanisms
Awareness of Ageing Responses to Questionnaires
• How are ageing effects taken into account in maintenance programme – From previous inspection data and structural
analyses – Periodic surveillance programmes gather data on
ageing effects – Trending of data provides an indication of future
problems– Future scenario’ analyses are performed to ensure
that ageing effects do not compromise integrity.
Competency• Increasing recognition of importance of
demonstration of competence• Developing regulations, codes & standards
recognising this• Competency in structural integrity
management• ISO 19902, NORSOK N-005, API RP SIM – list
competency requirements in SIM• Part of Questionnaire
Competency requirement – ISO 19902 (1)
• SIM process (engineer or group of engineers):– Familiar with relevant information involved in the SIM
process– Familiar with relevant information about the specific
platforms under consideration– Knowledgeable in offshore structural engineering– Knowledgeable about underwater corrosion processes
and prevention– Cognisant of the difference between design and
assessment engineering– Experienced in offshore inspection planning– Knowledgeable in inspection tools/techniques– Cognisant of general inspection findings in the offshore
industry
Competency requirement - ISO 19902 (2)
• Data collection & update –familiar with:– Structural arrangement, inspection techniques, analysis techniques,
interpretation, database admin., material specs. • Inspection Programme – engineer, familiar with the:
– content of the overall inspection strategy, and – with appropriate experience and technical expertise, related to tasks to
be performed
• Offshore Execution of Inspection Programme –supervisors, divers, ROV operators etc qualified to international or equivalent regional standards, with:– knowledge of how and where to look for damage, – experience in NDE methods, – Familiar with structure owner’s data validation & recording
requirements – divers (performing NDE) with accredited training/ qualifications)
Competency requirement –Feedback from Questionnaire
• Competence requirements– Competency requirements in job descriptions– On-the-job training– Gaps identified - based on these courses, seminars are
suggested – Ageing competency?
• personnel involved in SIM actively seek knowledge about structural ageing effects from the specialist contractors used for life extension assessment
• no formal training given• experience transfer, work experience, technical
literature, conferences• Limited!
Management of ageing equipment containing fluids or pressure - HSE
report RR509Competencies recommended:• Understanding of relevant regularity requirements,
codes of practice etc• Familiarity with the equipment concerned (design,
construction etc• Understanding of relevant degradation processes• Knowledge to plan inspection and maintenance for
safety• Experience of plant inspection, inspection
techniques & NDT, and their limitations• Understanding of fitness-for-service assessment
Emergency Preparedness• Awareness: How is emergency preparedness with respect to
structural related integrity managed? • How has the potential for incidents to have an impact on the
structural integrity been identified?• How have potential environmental, external (boat impacts etc) and
damage (cracks and deformations etc) effects on creating emergency situations been identified?
• Understanding: How have the probabilities and consequences of potential emergencies on structural integrity been assessed?
• How has the post-incident integrity for different scenarios been assessed?
• Preparation: How are installation specific features identified and incorporated into the emergency preparedness planning?
• How frequently are emergency exercises for structural hazards undertaken
Emergency Preparedness -Responses
• Scenarios that can impact structural integrity identified• QRA, risk and Emergency Preparedness Analysis,
design accidental load, ship collision analyses undertaken
• Probability and consequences of identified major accidents are assessed as part of the QRA.
• Structural damages are assessed as consequences to possible accidental events, e.g. collision, fire, explosion
• Emergency Preparedness Strategies and Action Plans are established based on the results of these assessments.
• Contractor has all structural models up and running and can quickly run a reanalysis
Emergency Preparedness -Responses
• Awareness of potential emergency situations?– Emphasis on ship collision
– Other emergency situations:• Structural degradation e.g. fatigue cracking• Effects of extreme waves, earthquakes etc• Combination of structural damage• Concrete structures - loss of drawdown
• Need for comprehensive risk assessment to identify emergency situations from structural failure
Conclusions• SIM an important aspect of managing offshore
installations, including effects of ageing• Concept of design life & processes for life
extension• Assessment process, including ageing and life
extension• Questionnaire – objectives and content• Selected topics for improvement (responses)
– Technical condition evaluation & reporting (KPIs)– Understanding of ageing mechanisms including
competency– Emergency preparedness ( as part of SIM) and
planning– Independent verification & QA/QC