mooring integrity & fuma why is it needed? how is it …€¦ · mooring integrity • moorings...

AOEC 14

Mooring Integrity & FUMA

Why is it needed?

How is it achieved?

Sept 2014

Mooring Integrity

• Moorings are Safety Critical Components, inherently protecting the vulnerable subsea architecture (risers, umbilicals, flowlines etc), together with hydrocarbon production and adjacent assets

• Mooring Failure is regarded as a Class 1 Hazard, the highest rating by the UK Health & Safety Executive

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Mooring Systems Typical Field Infrastructure

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Mooring Systems Typical Field Infrastructure

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Mooring Systems FPSO Expanding market

Source EMA 6/14 & Infield 6/13

• 264 FPS at 6/14, 60%

are FPSOs

• Compound annual growth of 18% to 2017, increasing in size, value & complexity

• 95% increase in 10 years to 2017

• Drivers - monetise gas at remote locations & focus on deep water

• Dominated by Africa, Latin America & Australasia


Prelude FLNG:

• 488m by 74m hull

• 600,000 tonne weight

• Kizomba A FPSO is 285m by 63m

• 90m high turret

• 250m water depth

• Cat 5 cyclones (>156 mph)

• 24 legs, 15.1 & 11.6 miles of chain & wire

Source: The Engineer 09 & ship technology.com

• 7-8 additional Asia-Pacific FLNG projects proposed

Source: Upstream 5/11

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Prelude LNG Terminal Kanowit LNG Terminal Abadi Bonaparte Scarborough

Operator Shell Exmar Petronas Excelerate Inpex Masela GDF

Suez/Santos ExxonMobil

Status (as of Feb ‘14)

Under construction

Under construction

Under construction

FEED completed

FEED in progress

FEED in progress

pre-FEED completed

Location 200 km W of

Australia Caribbean coast

of Colombia 180 km N of

Bintulu, Malaysia Lavaca Bay, Texas

coast 350 km E of East

Timor 170 km N of

Australia 220 km NW of

Western Australia

Water Depth 250 m Unknown 80 m Unknown 350-1000 m 85-100 m 900-970 m

L x B 488 x 75 m 144 x 32 m 365 x 60 m 338 x 62 m ~500 x 80 m ~400 x 70 m 495 x 75 m

Environment (Typhoon)

Hs: 11.0 m - Hs: 13.6 m - Hs: 5.5 m Hs: 11.0 m Hs: 13.0 m

Expected First Production

2017 2015 2015 2018 2019 2019 2020-21

Mooring Systems Hardware

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Mooring make up:

• Chain, mostly studless, up to 6.5 inch

• Wire – unsheathed or sheathed spiral or 6 strand

• Polyester rope – unsheathed or sheathed

• Connecting shackles

• Buoyancy support modules (buoys)

• Anchors or piles

Mooring Systems Hardware

Spread mooring Single point mooring - external turret Source: API RP 2SK

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Mooring Systems Vulnerability – inherent design

• Limited redundancy in mooring system, chain as strong as its weakest link

• Difficult to inspect & maintain, degradation & retirement issues

• Rapid incident escalation (eg cascading failure) in hostile environments

• Consequences lead to major loss including damage to subsea & seabed architecture and adjacent infrastructure

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Mooring Systems Vulnerability - Codes

Issues:

• Various codes on mooring design, less on installation, operation, inspection & retirement

• Differences in technical standards between Societies

• Regional differences within Societies – how good is the surveyor?

• Standards only periodically updated (behind the curve, e.g. new failure modes)

• Societies recognise that existing rules do not ensure FPSO mooring integrity

Source: Oil & Gas UK Report OP023 (2008)

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Mooring Systems Vulnerability - Codes

• Class Rules evolving from seafaring background

• Existing developments: Class - Ageing, many legacy systems in place (eg SPMs & offloading tankers). Equipment replacement considered as repairs, obsolete Class codes utilized

• Tanker conversions to FPSOs, change in duty

• New developments – Speedier, smaller operators, remote & unpredictable environments, deeper water, more subsea infrastructure, increased asset values

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Main Factors Influencing Long-Term Mooring Integrity including inspection and maintenance, mooring jewellery

Source: HSE 2006 study

•Also inspection and maintenance, mooring jewellery

Mooring Systems Vulnerability – mooring legs

Terminations:

• Hawse tubes - highest tension with

additional bending, twisting stresses & link contact wear

• Touchdown - heavy contact with sea floor containing rock of comparable hardness to steel -> severe localized wear

• Touchdown - accelerated corrosion (aerobic), chain moves above & below mudline, parent metal exposure

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Mooring Systems Vulnerability – fatigue

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Mooring Systems Vulnerability – corrosion

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•Corrosion comes in many forms…

• Design codes generally allow for <0.8 mm/year

•SRB Corrosion - In warm, shallow waters, often near river estuaries

• FPSOs with touchdown zone dynamics (eg draft change due to offloading)

• Corrosion rates at up to 2-4 mm/year

(Welaptega, 2014)

Mooring Systems Vulnerability - Ageing Assets

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Failure trends? – recent incidents

• Early life failures, design, manufacture, & installation

• Reduction in mid-life

• Increasing end of life failures; dominated by operational causes

(OTC 24181)

Mooring Systems Losses

Cascade Chinook - Loss 3/11

• 6.25” chain

• Faulty weld repair causes fracture in single chain link

• 440T buoyancy tank supporting hybrid riser released

• Chain vulnerable to hydrogen induced stress cracking – post heat treatment

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Recovered Subsea Arches

Gryphon - Loss 2/11

• winds > 55 knots, ~12m waves, 10 leg mooring, 18 year old chain

• Leading leg fails below design load

• DP loses heading, FPSO turns beam on

• 21 degree roll, 3 more legs lost

• 180m movement damaging subsea kit (Maersk, 9/11)

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Mooring Loss Statistics:

• 1 in 50 chance of a single line failure per floating asset per year. This equates to a 1 in 2 chance of line failure over a 25 (say) year design life.

• 1 in 350 chance of a multiple line failure (and/or infrastructure damage) per asset per year. 1 order of magnitude worse than industry (DNV) guidelines

• Permanently moored assets only. Based on known losses. (2001-11, 23 documented failures inc. 8 system failures, 4 with riser failure).

• Moving forward, these numbers are an underestimate. They do not recognise that all assets have continuously ageing mooring infrastructure.

• Mitigation, to reduce the chance of failure, is essential.

Source: Mooring Integrity Forum, Monaco, 2014, OTC 24025

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Floating Unit Mooring Assessment (FUMA)

• FUMA is an endorsement (not a warranty) for underwriters use.

• Insurers have relied on Class & Operators to ensure adequacy of design & Mooring System integrity.

• JRC mandated Engineering Sub-committee to investigate need for a formal process for Mooring System Assessment.

• Reflects other JRC Assessment Processes, discretionary/voluntary, flexible.

Mooring Systems FUMA


• An underwriting tool, value-adding for assureds.

• Structured consistently with other JRC survey documents eg CAR MWS & Well Plan review (Guidance Notes, Endorsement, Codes of Practice, Workscopes).

• Consideration given to International Standards, Design & Operation Codes, Integrity Management Systems, Industry Best Practice.

• Interaction with industry/operators and Oil & Gas Mooring Integrity Workgroup.



• Promote dialogue between Underwriters and Assureds, without dictating.

• Report becomes ‘Material Information’ & supports INFORMED underwriting decision making.

• Assist Underwriters in better understanding the Assureds operational practices, integrity management and experience.

• Enhance risk reduction for both Assureds and Insurers.


• Intended for Moored Floating Units OTHER THAN MODUs.

• Initial Screening Process (ISP) may indicate FUMA is not required (Generic considerations: Age, Design, Type, Class, Operating Standards)

• It’s a tiered process, light touch (Level 1) to full physical (Level 4).

• Entry can be at any level, but with all preceding levels performed (assessing physical condition is important but understanding Assured’s core philosophy is critical).

Mooring Systems FUMA – getting started

Mooring Systems Risk Screening

• Moored Risk Screening for FPSOs, FSOs, Spars, TLPs, SPMs & drilling units

• Used across a Portfolio of Moored Risks (or Operators) to assist Underwriters with risk mitigation

• Major incident likelihood (frequency) established by Naval Architects based on mooring complexity, age, design code, water depth, operational aspects, extreme environment vulnerability, inspection & monitoring etc

• Risk Consequence considers insured exposure, field infrastructure - subsea architecture, adjacent platforms

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•High: Intolerable Risks; mitigation is essential

•Intermediate: Unacceptable, reduce to ALARP

•Low: Acceptable: Consider ALARP

• Level 1: Remote Desktop & Correspondence

Review of design limits, operational procedures & history against relevant IACS standards and industry’s best practice.

• Level 2a/2b: Attended Technical Review

(2a: Attendance Onshore, 2b: Attendance Onshore & Offshore)

Attendance by Mooring Assessors of onshore facilities and, if required, of offshore location.

• Level 3: Physical Inspection

Physical inspection of moorings and third-party engineering as required.

• Level 4: Detailed Physical Inspection

Physical inspection of moorings to higher specification and third-party engineering as required.

Mooring Systems FUMA – assessment levels

• Can be at any point in moored unit lifecycle (pre or post installation – benchmarking, mid-life, if life extension planned).

• Uses competent Mooring Assessors; any party on which Insurers & Assureds mutually agree.

• Assessors may include Insurer’s internal engineering capability, and/or 3rd party (eg MWS with specialist mooring skills/experience, other specialist engineer).

• Workscope is applied. Assessor delivers findings to both Assured & Insurers.

Mooring Systems FUMA – when, how, who?

Mooring Systems FUMA - reporting

FUMA Level 4 Mooring Assessment - Tasks :

• Pre-engineering to tailor inspection campaign

• Offshore inspection campaign

‒ 2D/3D high def. focused visual inspections

‒ Chain/wire/fibre measurement tools, 3D modelling

• Review & report on risks associated with:

‒ Historic mooring failures and blackouts

‒ Operator Performance Standards

‒ Original design analysis and assumed extreme environment

‒ Operational philosophies and procedures

‒ Inspection findings

Mooring Systems FUMA 4 – typical tasks

FUMA Level 4 Mooring Assessment – Tasks:

• Review and report on risks associated with:

‒ Reported operations & offloading against original design inputs

‒ Mooring fatigue life re-assessment

‒ Subsea architecture complexity & vulnerability

‒ Collision risks & consequences – floating, water column & seabed

‒ Identify & report on ‘gaps’ in operations, maintenance and inspection procedures

‒ Recommendations for future inspection campaigns and wider mooring integrity management

Mooring Systems FUMA 4 – typical tasks

Mooring Systems FUMA & Integrity Management

Ideally a Mooring Integrity Management System exists:

• Part of Operator Safety Management System

• Developed, owned & administered by Operator

• Recognition that Moorings are Safety Critical

• Key components:

– System Description. Design, Manufacturing & Deployment

– System Performance Standards (specific, measurable, agreed, realistic & timed)

– Normal & Damaged Operational Procedures

– Component Risk Review (ALARP)

– Monitoring & Inspection driven by Risk Review

– Feedback into Performance Standards

– Suitable Tracking Systems to close out anomalies Source: Oil & Gas UK Report OP023 (2008)

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‒ Most likely failure modes ‒ Identification of critical components ‒ Mooring Extreme & Fatigue Analyses ‒ Max. Operational & Survival Conditions

•Pictures: BPP-TECH, 2012

• Analysis of vessel loading conditions and hydrodynamics (Orcaflex)

Mooring Systems

Tools used - FUMA4

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‒ FEA (Abaqus) for chain components ‒ In-house analysis models for damaged

wire ropes

•Pictures: BPP-TECH, 2013

• Analysis of structural integrity of critical components based on Welaptega inspection results and FEA

Mooring Systems

Tools used - FUMA4

Key high risk items identified in previous studies:

• Failure to establish meaningful root causes of historic failures

• Failure to implement recommendations made in internal accident investigations

• Absence of line-tension verification systems

• Lack of coherent emergency plans for mooring failures

• Mooring inspections not conducted deeper than 30m (air diving limit)

• Severe chain degradation known to operator – No action taken to manage reduced capacity

Mooring Systems FUMA – Identified Risks

Key recommendations made in previous studies:

• Root cause analyses to be completed by competent persons

• Engineering studies to account for ‘real-world’ condition of system

• Line-tension verification system to be installed as priority

• Mooring line failures to be simulated in drills and findings integrated in emergency procedures

• Comprehensive mooring inspection programme to be implemented

• Take ownership of mooring integrity management – don’t rely on Class Societies to do this for you

Mooring Systems FUMA – Recommendations

Development of effective mooring management strategies leading to:

• Safer mooring systems, less prone to failure

• Better “early warning” of mooring component degradation

• Rapid identification of failures through improved monitoring

• More efficient response of on-board and shore-based staff to mooring failure

• Minimisation of mooring failure consequences

• Reductions in number and size of insurance claims, improved insurance terms

• Lower downtime and improved productivity

• Improved industry reputation

Mooring Systems FUMA – Benefits

Lessons Learnt

• We NEED to know what we really have down there…

• How is it performing currently, how vulnerable is it

• How much longer is it going to be fit-for-service.

We don’t know what we don’t know

and we won’t know until…

We make a conscious effort to go and find out!

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Thanks for your attention and

Questions?

[email protected]

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