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The Alexander L. Kielland accidentThe Inquiry Commission’s

Investigation of the causes of the capsizing

and

the assessment of evacuation and rescue operations

and

the associated recommendations

&Some comments,

especially on what were NOT causes of the capsizing

Torgeir Moan

NTNU

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Content Mandate and members of the Inquiry Commission

Background: - Principles of accident investigations

- ALK (P89) lifecycle history vs status of technology & regulations

Possible causes of the accident

- The Commission’s approach: what causes platform accidents in general (i.e. the risk picture)

- «all possible causes» need to be investigated

Facts

- the «collapsed structure», environmental conditions at the time of the accident

- the life cycle info.: design and analyses (digital twin), fabrication- and operation reports, ..

- inspection of sister rig - Henrik Ibsen (P88) & other semi-submersibles

- Industry practice : rules & regulations – and their implementation in practice

- Examinations after the uprighting of ALK (in 1983)

- Personal comments about Expert and Witness statements & Media

Brief description of the causes of the capsizing and associated recommendations

- technical and physical a well as human and organizational factors for

A. structural failure(loss of column D) and

B. flooding and capsizing

- comments on circumstances that were not «cause of the accident»

Brief assessment of evacuation and rescue operations – and assoc. recommendations

Final remarks

«Media rumors»

Torgeir Moan, NTNU

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3 Mandate for the Inquiry• Investigate the conditions of the accident and, if possible, bring to light

the causes of the accident (and recommendations to improve the safety - as agreed with the Ministry of Justice after the appointment)

• Assess the performance of the rescue equipment and how the evacuation and rescue operation were executed and come up with recommendations

Inquiry Commission’s members• Thor Næsheim, Magistrate, Sandnes• Torgeir Moan, Professor, marine technology, NTH (NTNU)• Sivert Øveraas, Director, Shipowners association• Per Bekkvik, Platform manager/ship captain• Aksel Kloster, Personal manager, National Guard and Oil secr. LO

- later replaced by Jan B Strømme, «Oljekartellet»

Engagement of Kjell Straume, MSc as a technical secretary and several, independentexperts (e.g. from NTH,SINTEF, U.Aachen, Statoil) for special investigations

Torgeir Moan, NTNU

4Background: Principles for accident investigations

Technical/physical event sequence Deficient rules and regulations

(and industry practice at large)when it is realized that the industrypractice «at large» is not good enough

Human errors and omissionsby those- doing the job (and theirsuperiors in the organisation)during the different life cyclephasesor

- doing the control of integritymanagement during the lifecycleT

he

fa

cil

ity’

s l

ife

cyc

le p

ha

se

s

based on a «risk management tool»:Mangement Oversight Risk Tree (MORT),(Johnson, 1973)

Individual «errors» must be seen in view of the management-and safety culture in the relevant organisations and regulatory bodies

Torgeir Moan, NTNU

Fabrication

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5 Background: Principles for accident investigations, cont.d

Neutral presentation

J. Westerståhl in the book by Hadenius & Weibull (ed.) Massemedier, Aldusserien, Stockholm, 1978.

Holistic assessment of all possible causes/factors of influence – in an objective manner, i.e.:

Objectivity

Factuality Impartiality

Truth Relevance Balance

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Background: The development of the offhore O&G industry and the regulatory regime

Brief ALK historyo ALK was Pentagon-rig no. 9 (denoted P89)o Developed in the late 1960s, the first one, P81, was built in 1969

- The P82-P91 rigs were further developed and built based on «similar analysisand drawings» and delivered in 1973-1977 (CFEM, Rauma Repola, Marathon) .

o - ALK (P89) was approved in 1973-74 and delivered from CFEM in 1976.

Pioneering period for the Norwegian O&G activity :1970-1980

• Maritime Dir. regulations for drilling rigs1973, 1975 • DNV: rules for mobile rigs 1973 (ABS 1968)• Petr. Dir. was established in 1973 – Ptil separated as a unit in 2004• The Petroleum Law 1985 – Petr. Dir. as a coordinating body authority

Milestones:ALK accident in 1980Research Program «Safety Offshore» 1978-82- With several implications on safety efforts by the induystry and authorities

Torgeir Moan, NTNU

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- experiences from other accidents(Inquiry reports, risk analyses), e.g.

- assessment of regulations and standards & their use in practice

Background info. for the Inquiry

T.Moan: “Risk Assessment of Mobile RigOperations”, Report SK/R46, NTH, 1979, Safety Offshore (“Sikkerhet på Sokkelen”) research program.

Overview of world wide accidents for mobile platforms, made in connection with the finalizing of the ALK Inquiry Report: NOU 1981:11

organized according to the technical-physical sequence of events

Article published in «Teknisk Ukeblad»Vol.127. No. 11. 28.02.1980(a month before the ALK accident)

(1970-1980)

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8Possible causes of the ALK accident Possible causes (circulating in media

and also presented to the Commissionin various ways):

- open ventilators, watertight doors, - occurence of cracks

(the Commission informed the parties aboutthe D6 fatigue failureene 31.03.80)

- ship impact- «deficient platform structure, struct. materials- «overtensioning of mooring lines» –

especially the first days

- explosion (sabotage) theory The argumentation for and against the theories –

were influenced by self interests

(The Commission investigated the various potential causes, but only briefly mention factors that were insignificant to the causes of the accident, in the Commission’s report).

(published in 1981)

Hovden, Jan; Vinje, Kjell E. A.:Disaster journalism, the newspaper coverage of the "Alexander L. Kielland" platform accident, Yrkeslitteratur, Oslo, ca. 1983.

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- The «collapsed» struct.failure surfaces, material properties, (SINTEF, Statoil)

- Inspection of sister rig- Henrik Ibsen- inspection av the ALK platform

i 1980(!) and after uprighting in 1983

- wave-, wind conditions at the timeof the accident and during operation- design basis (drawings, criteria, analyses,operational manual), - fabrication- (inspection-) - and operational logs- annex: design calc. (stability and strength of hull and mooring system)

fatigue analyses (which were not carried out for design) (SINTEF/NTH, U.Aachen)stability- and flooding analyses (NTH)

- review of relevant regulatory requirements and their use- interrogation/hearing of designers, fabricators and inspectors during

fabrication, class societies, Maritime Dir., Petr.Dir., owners, survivingmaritime crew and hotel guests (normally together with the Stavanger Police)

Facts in the Inquiry

(D-column, diver-inspections , especially with respect to cracks at other locations – e.g. on brace B5,Material tests , etc)

Torgeir Moan, NTNU

10Personal comments about Expert & Witness statements & Media Hearing of involved parties:

- The French designers and fabricators, classsociety (DNV, Lloyds Register (LR) , Mar.Dir.,Operator (Stavanger Drilling)specialists on strength and stability analysis

- Maritime crew- Others (hotel guests)

Opinions expressed by other org. and media

Many persons – also engineers – have made statements about the accidentwithout a holistic perspective of the facilityand its life cycle history.

For instance, media have speculated onthe accident causes based some physicalobservations during operation by personnelon board – without insight about the design and fabrication (e.g. the digital twin of theplatform) – and often with a certain (hidden) «agenda».

Necessary perspective:Relevant engineering competence, familiarity with accident taxonomy

Operation

Fabrication

The accident tookplace during operation

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Document delivered to theMinistry of Justice, March1981: NOU 1981:11- Main report 216 pages- Technical annexes 143 pages- Documents from different experts

«unauthorizedtranslation»

Mandate•Investigate the conditions of theaccident and, if possible, bring to light the causes of the accident(and reommendations to improvethe safety (as agreed with theMinistry of Justice after theappointment)

•Assess the performance of therescue equipment and how theevacuation and rescue operationwere executed and come up withrecommendations

In Norwegianwith a summary in English

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In 1983 (after uprighting):- Further investigation of structural

damages relating to the accidentcauses(hampered by damages causedduring the uprighting of the platform)

- Status of doors, ventilators andvalves (associated with flooding,capsizing)

Uprighting of ALK

In 1980:Inspection of the D-column andthe platform:- dry inspection of pieces cut at

failure locations- under water inspections by divers

on behalf of the Commission

Additional documentAfter uprightingDelivered in 1983:NOU 1983:53

The main motivation (of the government) for the uprighting was the search for the remains of 36 missing persons

Torgeir Moan, NTNU

Parliament message No. 41, 1983-84

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Accidents can be investigated from: Technical-physical point of view

- Capsizing or total loss of structural integrity commonly develops in a sequence of events

Human and organizational point of view («Root Causes»)- All decisions and actions

made – or not made duringthe life cycle are the responsibility of individuals and organizations

Accident Causes

Criticalevent

Fault tree

Event tree

- Fatalities

- Environmental

damage

- Property

damage

based on the «tool»:The Management Oversight and Risk Tree – MORT (Johnson,1973; User manual EG&G,Idaho Inc.,1976)

Torgeir Moan, NTNU

14 The overall accident (technical-physical) sequence

- Column D is lost due to structural failure

- Heeling: 30-35- Flooding of deck and columns

- Capsizing

after 20 min

-123 fatalities(among 212 persons on board)

- total loss of the platform

Evacuation- and Rescue operations

Torgeir Moan, NTNU

(Moan, 1981, 1985)

The scenariofor escape, evacuation and rescue

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15Loss of column D: Technical-physical causes

Fatigue failure inbrace D6

Overload (failure) ofthe other 5 bracesbetween column Dand the platform

Loss of column D

BraceD-6

Fatigue failure Column D

D

Based on all physical evidence and numerical analyses

Plate thickness not in scale

D6 plate Hydrophonesupport

CrackInitiation I

Crack Initiation II

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«possible» additionalBrace between C and D not included in thedesign due to considerations of supply ship operations

16 Fracture mechanics analysis of theAlexander Kielland fatigue crack

BraceD-6

ED

(Moan et al., 1981;Moan, 1985, 2006)

D6 plate 70 mm crack with paint inside

Hydrophonesupport

Caculated expectedtime to failure: 3-4 yrs; ( ca 7 yrs without thegross welding defect)

Plate thickness not in scale

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17Capsizing (flooding and capsizing)Background: - The Scenario: Loss of a column

- Design of floating platforms to limit the risk of capsizing orprogressive flooding (Ch.3.2 in NOU1981:11): Intact anddamage stability requirements

Design and operational issues relating damage stability requirements- water filling of 1-2 compartments, typically up to ca 600 m3 in total for columns in ALK.- Doors and valves submerged in the new inclined floating position (typically 22-24 heeling)

should be (closed and) designed to tolerate the water pressure to avoid progressive flooding –otherwise it needs to be shown that the capsizing criteria are fulfilled under the revised floodingcondition

- Inaccurate stability analyses (in design) implied a payload capacity of 1600-1700 t (not 2100).However, the payload was about 1050 t at the time of the accident

- There was also some doubt whether the drainage valves fulfilled IMO’s Load Line convention.- On the other hand, the designers specified in the operational manual some requirements

to keeping doors in the deck shut – even if according to the initial stability checks the deckwas not going to be submerged into water and hence no requirements to closing ofopenings in the deck.

NOTE: The main issue is that the scenario with the loss of the column D, was dramatically differentfrom the existing design stability criteria. The discrepancies in the stability analysis andoperational follow up, are not significantly contributing to the accident .

Torgeir Moan, NTNU

18Capsizing: Technical-physical Causes of the Capsizing given loss of column D – (3.2.5.4 i NOU1981:11)

Lowerdeck

Deck sides

Differentopenings

Note: some extra marginregarding deck load(1050 vs 1600-1700 t)

As suggested in Sect. 3.2.5.4 there were also some (small) openings in the deck that should have been closed according to the operational manual (since the designer tried to make the deck buoyant ) – however, it might be unrealistic to expect this to be done in the relevant scenario .

Torgeir Moan, NTNU

Loss of column Dresulted in aninclination of 30-35

Flooding of of the trunk and dry tank in column Eand trunk in column C and 50-75 % of the9600 m3 deck volume

- Closing ventilators wasrequired at a draft of 20.7 m. Failure to do so, couldhave contributed to a slightly more rapid flooding(Sect. 3.2.5.4, Annex 1,1.3)

Capsizing afterabout 20 min

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19 Root (Human & Org. factors) Causes of Structural Failures and Risk Reduction MeasuresCause Risk Reduction Measure Quantitative

method

Less than adequate safety margin to cover “normal” inherent uncertainties.

- Increase characteristic load, safety factors/margins in ULS, FLS;

- Improve inspection of the structure (FLS)

Structural reliabilityanalysis

Gross error or omissionduring life cycle phase:- design (d)- fabrication (f)- operation (o)

- Improve skills, competence, self-checking (for life cycle phase: d, f, o)

- QA/QC of engineering process (during d)- Direct ALS design (in d)– with

adequate damage conditions arisingin f, o (NOT d)

- Inspection/repair of the structure(during f, o)

Quantitative risk analysis

Unknown features or phenomena

- Research & Development Indirectly: Technology Readiness Level

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20Basic case: Causes of Structural Failure & Capsizing structural failure occurs when the load effect, S > the resistance, R:

- S and R are uncertain due to fundamental variability (e.g. in loads) and lack of data.Design : Rc/R > S Sc is based on accepting a certain failure prob.

- errors or omissions in design, spec.of fabr. (and oper. ) - too low strength of components …,e.g. not doing fatigue design check;

using too low sea state (error by designer or deficiency of industry at large)

- errors or omissions during fabrication- use of deficient material- welding faults: excessive defects and geometrical deviations

- errors or omissions during operation:- abnormal loads (payloads, ballast, environmental loads- accidental loads (fires, explosions, ship impact,

abnormal ballast distribution...) beyond design- abnormal corrosion or crack growth- excessive mooring loads due to maloperation

- deficient rules and regulations,(in the industry «at large») - or practicing of them

- deficient control of design, fabrication or operation

Torgeir Moan, NTNU

Capsizing occurs due to overturning moment exceeds hydrostatic stabilizing moment – can be treated in a similar manner

Tech.-phys.Calculated, accepted risk

Human & org. factorsnomallydominating the actualrisk

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21Brief Summary of the Alexander L. Kielland CapsizingTechnical causes &consequences

• fatigue failure of one brace- initiated by a gross fabrication defect (crack) anddeficient fillet weld

- low fatigue life

• ultimate progressivefailure of braces

• loss of column D,listing of 30-35,loss of pump capacity& progressive flooding

• capsizing (after 20 min)

Human and organizational factors (Root Causes)

• fabrication defect due to - deficient weld design- bad welding- inadequate inspection

• no fatigue design check carried out

• codes did not require structuralrobustness (damage - tolerance)

• damage stability rules did not coverloss of a column (implying a net buoyancy loss of 2-3 times thecommon “damage”)

• failure to shut doors, ventilatorsetc. “contributed” to the rapid flooding and capsizing

Plate ofthe brace

Hydrophonesupport

Filletweld

Human and organizational errors and omissions as well as deficientIndustrial practice

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22 CommentsHuman & Org. Errors and Omissions in view of The state of knowledge/practice at large in the

industry, regulatory bodies (Mar. Dir., Class. Societies):- regulations and design codes appearing in 1973 and - control practice – limited semisub. platform years of operation),

research community- significant research on fatigue of welded offshore structures

in 1970-75

Accident experiences

The state of art in technologydesign fabrication operationQA/QC - inspection, - inspection

- the accidentALK: -19741) 1976 1976 ……- 27.03.19801 P89 - no.8 of 10 sister rigs designed approx. in 1971- 75

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Example:Fatigue analysis and design

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23 Historical notes on fatigue analysis & design - 1840- 50

- 1847- 70

- 1895

- 1948

- 1953

- 1950’s

- 1960’s

- 1963 (61))

- 1969-73

- 1970-75

- 1979

- 1980

First fatigue failures - of vehicle and machine shafts - documented in journalsWöhler’s scientific investigations………………………………..

Kipling’s description of propeller shaft fatigue failure in ”Bread upon the waters”

Nevil Shute’s description in ”No Highway” of airplane loss due to fatigue………………………………..Comet airplanes lost due to fatigue

Fatigue failures of welded bridges and ship structures – and R & D

Textbooks on fatigue of welded structures

Paris-Erdogan’s law ( fracture mechanics)

Offshore Rules with fatigue requirements

Significant fatigue R&D for offshore structures………………..Ranger I jack-up failure in the Gulf of Mexico………………..The Alexander L. Kielland accident in the North Sea

Torgeir Moan, NTNU

(Moan, 2006)

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Involved parties (except the French designers/fabricators), generally agreeon the conclusions (see e.g. Parliament message,No.41,1983-84), even ife.g. the Mar.Dir. and DNV were critized in NOU1981:11. The international offshore engineering community also agrees.

Some media, for various reasons, have, especially in the last few years, made («fake») news based on witness statements especially from survivors, said to be new observations, - however without knowing the existing documentation (facts) or - seeing it in a holistic perspective (lacking the use of the informationgenerated through digital twins of the system and operations).

- another issue is what is the trustworthiness of recent statements – 35-40years after the accident.

The commission based its investigation on all hypotheses. In the followingI will comment on frequently mentioned hypotheses regarding the loss of column D:- cracks, ship impacts, explosions and possible effect of mooring system.In the report NOU1981:11 such hyptheses are briefly mentioned - and why they cannot be the causes.

Comments on the report NOU1981:11 & Media

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25Cracks – rumors and facts Design and inspection plans (no fatigue design)

- The platform had been subjected to annual, visual inspections by crew members, with a limited likelihood of detecting e.g. small cracks.

- Visual inspection had been carried out on selected joints - The 4-year main inspection should have taken place in june 1980

but was granted a year delay, based on an application. (The critical crack on brace D6 might have been detected during a main inspectionif the inspection at this location had been prioritized)

- Another matter: statement by platform chief engineer (07.03.1986) that he and the platformmanager proposed to PPCoN that the lower braces could be inspected in August 1979 in connection with the the move of ALK in a deballasted condition to Edda - but was not done.

Observations/findings during the operation of ALK (before the accident)- the platform manager reported cracks on crane supports, that were

repaired in 1979 (p. 53 i NOU1981:11, see also p.237)After the accident there were rumors: «The platform manager knew aboutcracks». The cracks at the crane support was probably mixed up with the cracksin brace D6 that was reported by the Commission on Mach 31 1980.

Observations after the accident- initial cracks at the hydrophone support on D6- other cracks in ALK and other Pentagone & other platforms,…?

(p. 55, 58 in the report). Diver inspections on ALK, without crack findingsat the opposite hydrophone holder on brace B5 (p. 55, column 2)

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Ship impact hypothesis Ship impact was suggested as a cause or at least a contributing cause of

the accident – also by CFEM – Forex Neptune. Extreme char. line tension (in B1-B2) was estimated to be of the order of

2.0 – 2.6 MN and 0.8 - 1.3 MN at the time of the accident (smaller for D1-D2).

The tensile capacity of the intact brace D6 was about 70 MN.

For a ship impact to cause failure of an intact brace forces of the orderof several MN need to occur – also imposing damage at the impactlocation

The observed damages that could be due to ship impact (contact) aredescribed in NOU1981:11, p. 52-53 - a dent with a depth of 1’’ (25 mm) on brace C-2, between stiffeners atthe 3. ringstiffener, 6 m from the lower end of the brace - attributed to a contact with a supply vessel on 21.10.78.

- a dent of the same size in column D, 10-12 m from the top of thecolumn, 3-4 m above still water level

These indentations do not correspond to impact forces that can causefailure of an intact brace D6.

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• Launched early (see Media report of the early stage by J.Hovden og K.Vinje, 1981)a) first as «explosion-»sabotage hypothesis (by Østlund, «Kiellandfondet», book

by B.Nilsen «The Ghost in the Nort Sea», 1984)b) later as an «accidental condition», relating to welding station or moving of «gas

containers».

Explosion hypotheses

Scenario a:- material tests (at UiO), said to be from the upper end of the

D4 brace, claiming that the microstructure of failure surfacesis due to high pressure and temperature - and hence causedby an explosion. (prof. Gjønnes, UiO, responded «no» to thequestion whether «explosion could be excluded»).

- no footprint due to heat found at failure locations- failure mode at failure locations not compatible with a possible

internal/external pressure load. The actual failure of bracesother than the D6 show sign of compression and bending ofthe braces, taking place rapidly, in agreement with thecalculations in Ch.5.3 (Table on p.278) and material investigations by SINTEF (annex 8, NOU1981:11) and a laterstatement e.g. from prof. T.Grong there is no support of theUiO conclusions.

- there is no motivation identified for an intended sabotagenor any witness statements that can support this hypthesis.Typical brace

failure modeTorgeir Moan, NTNU

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Scenario b: an explosion in the welding station (relatedto gas «containers»), causing «rystelser» (shaking) thatcaused failure at two locations in brace D4 (locatedsome distance away from the welding station). - No quantitative justification has been given regarding

explosion pressures and the shaking at D4 (forcesin D4). Why should failure occur there and not otherplaces?

- no apparent damage at the location of the weldingstation - where the explosion is said to occur

- there is no witness statements about explosionevents

Additional note

Explosion hypotheses, continued

Damages at the node between brace D4 and the lower deck discovered during inspection of the uprighted platform is explained by high forces during the uprighting by the buoyancy bag attached there

BraceD-6

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The mooring system was initially designed with 10 steelwire lines. At the «Edda 2/7 C» 8 lines were used (C1&C2 lines were not used)

The 10-line system was approved by the Maritime Dir., but not the 8-line system (p.53-54 and Annex 5 of NOU1981:11)..

DNV was involved in approbation of the mooring system in connection with insurance in 1977.

The Commission made alternative mooring anlyses to illustrate the effect of more refined and stringent design analyses (emerging around 1980) due to high line failurerates and «motivation» implied by the ALK accident

The 8-line ALK mooring system used at Edda 2/7 C actually did not satisfy ultimate strength design req.(p. 47 in NOU1981:11, and details in Annex 5)

The environmental conditions at the time of the accidentwere moderate («fresh gale – stiv kuling», not storm!:

- sign. wave height (Hs) 6 m (< 50 % of extreme value)

- mean wind speed, about 16-20 m/s, approx. from East

Line tension : 50 % of the extreme value. The tensionin the leeward lines D1 og D2 (and E1/E2), is even lower, about 60-90 t.

Possible influence of mooring system issues on the accident Background

The procedure for relocating the platform is described on p. 222 in NOU1981:11.

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Line tension measured to 40 t and measurement system foundto be ok at 05:00 on 27.03.1980 (p.53, 55 i NOU1981:11)

Hs increased from 3 to about 6 m from 09:00 to the time of theaccident and the platform was relocated – away from Edda 2/7 C, by reducing the tension in D1/D2/B1/B2, and increasing tension in A1/A2/E1/E2 (p. 55). The relocation took place without anyproblems and was completed at 17:50 – with a tension levelof about 40-60 t. The accident happened at 18:30

Hypothesis 1: High mooring tension ripped off the column D: - assume conservatively that both lines D1 og D2 have a tensionat ultimate strength, i.e. each 304 t – 4 times the most likelylevel. This implies a stress in an undamaged brace D6 approx.

10 % of yield level and about 2-4 % in the actual conditions(Annex 5, p. 261, 275 and Annex 7 in NOU1981:11).

Hypothesis 2 : Operational error during relocation causing anabnormal mooring tension that ripped off the column D- The Commission had no reason to believe that there were

errors made during the relocation, causing excessive stresses,contributing to the failure of the brace D6. (NOU181:11, p.55)

- the normal tension in the lines contribute to the stresslevel in the brace and hence the fatigue failure and finalrupture. Since this effect is very small for an intact brace, evenpossibly neglecting this effect is a minor «error».

(p.53, 55, 56, 57 and Annex 5 og 7 in NOU1981:11)Possible influence of mooring tension on thestructural failure?

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Focus on holistic, unified safetymanagement in view of all hazards(risks) and measures to limit the risk

Improved standards/guidelines regarding strength and stability- damage tolerance

Improved practicing of standardsand quality control (design, inspectionduring fabr. and operation)

Organization of safety controlGovernmental inst. vs delegation,e.g. to class soc. – especially in view ofnovel type of platform function or layout

Ensuring competence and creating safety attitude in involvedorganizations

Recommendationswere weighted to balance requirementsin view of the total risk picture (accidentpotential)

Rather than to«overreact» on thefeatures of theparticular accident- Example: conflicting

requirements to thedeck structureregarding possible(emergency) buoyancy, evacuationways, fire/explosion

Recommendations (strength & stability)

Limited focus on R&D

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In general, this accident gave the momentum to a «new deal» in offshore safety in Norway…..

32The most important recommended new design requirement: A general principle for damage tolerance: - As implemented by NPD in 1984 as ALS and later in international codes

b) Global structural failure due accidental loads or abnormal strength

c) Mooring system failureafter «loss» of one line

Important recommendation even if mooring system issues cannot be said to be a contributing cause of the accident.

a) Capsizing due to flooding/buoyancy loss

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- Extend existing damage stability criteria(based on specified vs risk-based criteria)

- Revisit assumption regarding of closing openingsin the deck during operation

- Introduce damage tolerance criteria for the hullstrength and mooring system

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33 Assessment of evacuation and rescue operations and equipment The accident scenario

- 20 min before capsizing- no el. power- loose equipment

blocked doors- only 2 of 7 life boats

were «successfully»used

- survival suits werenot mandatory

Status of evacuationmeans (life boats, life rafts,survival suits, means ofrescue (stand-by vessel… helicopter….in the field )

Regulations, rules Assessment

- assisted by NSFI/Marintek, Interrog. of survivors

Net loss of buoyancy: 1300 m3 (as opposed to typical flooding in damaged condition: 600 m3 , p. 245-247, 357

123 fatalities Total loss of the platform

B

Lifeboat, attempted launched, crushed against the platform

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212 persons on bord

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Escape ways B

C

E – not shown

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Upper deck view, with all life boats(life boats 1, 2 on the lower deck

Intermediate deck

Lifeboats at the top of the column

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Technical-physicalcauses

• the accident scenario:

- sudden 30-35 heeling,

- capsizing in 20 min.

- low water temp.

- hotel platform with

212 persons on board

• deficient evacuation

and rescue operation

(lack of survival suits,

limited available and

“lauchable” lifeboats,

stand-by vessel and other

rescue fcilities

equipment)

Human and organizational factors

• the accident scenario was not anticipated

in facility design, and the planning of

evacuation and rescue operations

• deficient requirements to

- lifeboats, survival suits , stand-by vessel

etc

- safety training (courses and exercises).

(Still, experienced seafarers managed well)

• long mobilizing time for rescue (stand-by)

vessel, (helicopters)

Causes of the ultimate consequence: Fatalities

- The role of evacuation and rescue operation

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37Recommendations relating to evacuation and rescue

• Holistic view of accident scenarios “Marine events”

(heeling platform, flooding, …)

Fire and explosions (toxic smoke, heat,….)

• Design of the facility - design the platform to avoidaccident scenarios such as that of ALK

- distance between hazardous areas and living quarters

- type and location of lifeboats etc- protection of potential evacuation pathsand means of evacuation

evacuation means:number and quality of life boats(free fall rather than launchable life boats)200 % coverage of lifeboats, survival suits

Important to balance conflicting requirements relating to marine and «industrial» accidents

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Recommendations relating to evacuation and rescue

Establishing area emergency system

Stationing of helicopter for rescue operations

Stand-by vessel in the field

Mandatory safety course, training and exercises for alloffshore personnel

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Concluding remarks

• «Errors and omissions» in the design and fabrication were the rootcauses of the accident, however, to some extent reflecting the «limited» state of knowledge in the industry in the first part of the 1970s.

• This accident lead to a focus on safety requiremets and practice (by providing the momentum to introduce long due principles) - providing safety with respect to catastrophic consequences

relating to operational errors by requiring damage tolerancewith respect to global structural failure, capsizing or total failure ofthe mooring system

- avoiding fatigue failure by proper design, as well as inspection,maintenance and repair during operation

- design the platform for efficient escape and evacuation, improvedevacuation means and procedures evacuation and rescue – andsafety education and training

The ALK accident marks the «end» of the pioneering period (1966-1980) of offshore oil and gas activities in Norway

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Maintaining safe facilities and operations, requires a safety attitude

by all personnel involved in the whole lifecycle.

Such an attitude is supported by motivatione.g. from the lessons learned from previous accidents,

focusing on human and organizational factors

THANK YOU!

Significant changes in safety management have been formally implemented in Norway. (NOTE: 105 of 106 safety improvements recommended by the Cullen report following the PiperAlpha disaster had already been implemented in Norway following the earlier accident – Reid, 2020.)

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Selected references beyond NOU1981:11 and NOU 1983:53 and references given in these documents

• Hovden, Jan; Vinje, Kjell E. A.: Disaster journalism, the newspaper coverage of the "Alexander L. Kielland" platform accident, Yrkeslitteratur, Oslo, ca. 1983.

• Johnson, W. G. THE MANAGEMENT OVERSIGHT AND RISK TREE – MORT Idaho Operations Office and Aerojet Nuclear Company Grandjean Lowman, Idaho 83637 (4566River Street Willoughby, Ohio 44094). Prepared for the U.S. Atomic Energy Commission, Division ofOperational Safety. 1973. User manual EG&G, Idaho Inc.,1976.

• Moan, T.: “Risk Assessment of Mobile Rig Operations”, Report SK/R46, NTH, Trondheim, 1979.• Moan, T.: Kunnskap og holdning vil alltid være viktig for sikkerheten, Teknisk Ukeblad, Vol.127,

no.11, 28.02.1980• Moan, T.: The Alexander L. Kielland accident, First Wallace Lecture, Massachusetts Institute of

Technology, Cambridge, 1981.• Moan T., S. Berge and K. Holthe: Analysis of the fatigue failure of the "Alexander L. Kielland", ,

Americal Society of Mechanical Engineers (ASME) Annual Meeting, Washington DC, November 1981.

• Moan, T.:The progressive structural failure of the Alexander L. Kielland platform, Vienna: Springer, 1985.

• Moan, T.: Fatigue Reliability of Marine Structures – from the Alexander Kielland Accident to Life Cycle Assessment of Safety", ISOPE Keynote lecture, San Francisco, 2006, J. ISOPE, 2007,17(1), 1-21.

• Reid, M. The Piper Alpha Disaster: A Personal Perspective with Transferable Lessons on the Long-Term Moral Impact of Safety Failures. ACS Chem. Health Saf. 2020, 27, 2, 88–95

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