Design for Safety Risk-Based Ship Design Dr Dimitris Konovessis - - PDF document

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Design for Safety Risk-Based Ship Design Dr Dimitris Konovessis - - PDF document

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Design for Safety Risk-Based Ship Design Dr Dimitris Konovessis Naval Architecture and Marine Engineering MJB Technical Talk 28 March 2013 Presentation Outline Recent Developments in Ship Safety: Goal- Based Approaches and Risk-Based

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Design for Safety

Risk-Based Ship Design

Dr Dimitris Konovessis Naval Architecture and Marine Engineering MJB Technical Talk 28 March 2013

www.safety-at-sea.co.uk

Presentation Outline

  • Recent Developments in Ship Safety: Goal-

Based Approaches and Risk-Based Design

  • Safety Level (Total Risk) Modelling

Flooding Survivability Analysis Fire Safety Analysis Post-Accident Systems Availability Analysis Evacuation and Rescue Analysis

  • Concluding Remarks

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www.safety-at-sea.co.uk

Presentation Outline

  • Recent Developments in Ship Safety: Goal-

Based Approaches and Risk-Based Design

  • Safety Level (Total Risk) Modelling

Flooding Survivability Analysis Fire Safety Analysis Post-Accident Systems Availability Analysis Evacuation and Rescue Analysis

  • Concluding Remarks

3

www.safety-at-sea.co.uk

Safety

  • escalation in size
  • specialisation
  • higher speed
  • construction materials
  • over-capacity
  • greater complexity
  • more information
  • less time
  • competition
  • manning
  • ageing fleet

Shipping

  • public expectation

for higher safety

  • Increased public

regard for human life and environment

  • media coverage
  • political pressures

Society Science & Technology

  • phenomenal progress
  • rapid technological

change

  • better technical

capabilities

  • innovation potential
  • cost-effective safety

The Changing Face of Ship Safety

Safety Drivers

Need for change

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A New Philosophy

“Design for Safety”

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Risk is an Inherent Feature in the Maritime Industry!

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SOLAS

Minimum standards Statistical average Historical risk

Compliance with Rules/Regulations

Containing Risk Today

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Deterministic Rules

Criteria Estimation

GZmax vs. Hs

1 2 3 4 5 6 7 8 9 10 0.05 0.1 0.15 0.2 0.25 0.3 0.35

GZmax (m) Hs critical (m)

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Deterministic Rules

SOLAS ’90 Standard

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Safety Level in Rules is Unknown!

1-Comp standard: High likelihood x Severity?? 2-Comp standard: Lower Likelihood x Severity??

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1 2 3 4 5 . 2 5 . 1 2 5 . 2 2 5 . 3 2 5 . 4 2 5 . 5 2 5 . 6 2 5 . 7 2 5 . 8 2 5 . 9 2 5 Non-dimensional penetration New Database Old Database

Rules do not always reflect experience

B/5 Bulkhead

www.safety-at-sea.co.uk

Requirements Concept Design Studies Final Concept Design Solution

Time

Contract

Design Today: Rules-Based Design

Logistics Business “Perceived” Risk Needed functions, basic services, costs, earning potential, etc… Expected safety level for all accident categories Regulations: subdivision, double hull, LSA, fire protection, etc. Long promenade, pod propulsion, low NOx/SOx, high speed, manoeuvrability, etc.

Owner

Concept Design Studies Final Concept Design Solution

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Requirements Final Concept Design Solution

Logistics Business “Perceived” Risk Needed functions, basic services, costs, earning potential, etc… Expected safety level for all accident categories Regulations: subdivision, double hull, LSA, fire protection, etc. Long promenade, pod propulsion, low NOx/SOx, high speed, manoeuvrability, etc.

Owner

Time

Contract

Functionality Safety Rules Performance

Design Today: Rules-Based Design

Concept Design Studies Concept Design Studies

Yard

Experience, Talent! Available Knowledge Design Tools & methods

Damage stability and survival capaility Cost estimates Logbased WP1 Input (Module 1 to 6) Lines and body plan Hydrostatics and hull shape Hull arrangement and freeboard General arrangement Powering and propulsion arrangement Light ship weight and capacities Structure arrangement and strength Trim, intact stability Final design

Dillon, 1969 and Erichsen 1989

Proportions and preliminary powering Damage stability and survival capaility Cost estimates Logbased WP1 Input (Module 1 to 6) Lines and body plan Hydrostatics and hull shape Hull arrangement and freeboard General arrangement Powering and propulsion arrangement Light ship weight and capacities Structure arrangement and strength Trim, intact stability Final design

Dillon, 1969 and Erichsen 1989

Proportions and preliminary powering

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Safety is treated a Rule Compliance

 This can not nurture a safety culture!

Quality

Evasion Culture Safety Culture Compliance Culture

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Adopt a Goal-setting Approach

Functionality Performance Safety rules Innovation potential Design Solutions Space

“Better” Design

Design solutions developed to meet “safety goals” (beyond rules) alongside other design goals

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Provide Feedback on Life-Cycle Issues

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Use routinely First-Principles Tools

Time

Contract

Concept Design Freedom to make changes Knowledge about the ship Assigned Costs

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Time

Contract

Concept Design Freedom to make changes Knowledge about the ship Increased knowledge

Decision making shift

Use routinely First-Principles Tools

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Requirements Concept Design Studies Final Concept Design Solution

Logistics Business “Perceived” Risk Needed functions, basic services, costs, earning potential, etc… Expected safety level for all accident categories Regulations: subdivision, double hull, LSA, fire protection, etc. Long promenade, pod propulsion, low NOx/SOx, high speed, manoeuvrability, etc.

Owner

Time

Contract

Functionality Safety Rules Performance

Yard

Experience, Talent! Available Knowledge Design Tools methods

Damage stability and survival capaility Cost estimates Logbased WP1 Input (Module 1 to 6) Lines and body plan Hydrostatics and hull shape Hull arrangement and freeboard General arrangement Powering and propulsion arrangement Light ship weight and capacities Structure arrangement and strength Trim, intact stability Final design

Dillon, 1969 and Erichsen 1989

Proportions and preliminary powering Damage stability and survival capaility Cost estimates Logbased WP1 Input (Module 1 to 6) Lines and body plan Hydrostatics and hull shape Hull arrangement and freeboard General arrangement Powering and propulsion arrangement Light ship weight and capacities Structure arrangement and strength Trim, intact stability Final design

Dillon, 1969 and Erichsen 1989

Proportions and preliminary powering

Safety Objectives

Verification

  • f “Safety Performance”

by First-Principles Tools

Additional Functional Requirements Design Criteria

Risk-Based Design

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Risk-Based Ship Design Principles

  • Adoption of a formalised procedure to

measure safety consistently (risk analysis / risk assessment / risk management)

  • Integration of such procedure in the

design process (integrated design environment)

  • Flexibility to allow trade-offs between

Performance, Earnings, Risk (Safety) and Costs

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RBD High-Level Framework

Integrated Design Environment [Software Platform]

Evaluation of ship performance Requirements and Constraints Ship functions and performance criteria Performance Expectations

Design safety goals Definition of design safety goa and functional requirements / preferences Identification of hazards Identification of possible design solutions (focus on accident prevention) Identification of critical functions, systems and relevant key safety parameters Identification of critical/design scenarios (flooding, fire, system failure, etc) Risk Analysis How probable? How serious? (Level of detail depends on design stage) Risk Assessment Implementation of risk control measures (focus on preventing occurrence of accidents)

(i) (v) (iii) (ii)

SAFETY ASSESSMENT PROCEDURE

safety performance

Design Decision- making

SHIP DESIGN

risk technical performance costs aesthetics company/society values, preferences

Systems, components, hardware (design solution)

fitness for purpose feasibility

(iv)

Meeting Safety Objectives Satisfying Design Goals

RBD  Design with known safety level

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RBD and Innovation

Low Nothing new or unusual Well understood issues Established practice Medium Uncertainty/deviation from standard practice. Possible safety trade-offs. Economic and lifecycle implications. High Novel or/challenging

  • concepts. Large
  • uncertainties. Significant

safety trade-offs. Codes & Standards SAFETY RULES First-principles RISK ASSESSMENT Engineering judgement

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Presentation Outline

  • Recent Developments in Ship Safety: Goal-

Based Approaches and Risk-Based Design

  • Safety Level (Total Risk) Modelling

Flooding Survivability Analysis Fire Safety Analysis Post-Accident Systems Availability Analysis Evacuation and Rescue Analysis

  • Concluding Remarks

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www.safety-at-sea.co.uk

Mitigation Analysis Accident Causality Analysis

Casualty Threshold /Safe Return to Port

Consequence Analysis

Scenarios Flooding survivability analysis

Systems Availability Evacuation & Rescue

Scenarios Flooding survivability analysis Scenarios Fire safety analysis

Collision Collision Grounding/ Stranding Grounding/ Stranding Fire Fire

Systems Availability Evacuation & Rescue Systems Availability Evacuation & Rescue

Safety Level (Total Risk)

Safety Level – Evaluation Framework

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Ship Safety Level (Total Risk)

  • Risk is a chance of loss of life
  • The chance is measured by statistics

loss of life

(expected number of fatalities per year)

flooding fire intact stability loss

  • ther

loss scenarios: ~90% of the risk

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Example Loss Scenario

Flooding | Collision

Water ingress (hull breach) Loss of stability Navigation failure Abandonment prevention mitigation

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Risk Model

   

 

max

1 N i N PLL

i F N E Risk

   

max

N N i N N

i fr N F

1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 1 10 100 1000 10000 Fatalities [N] Frequency of N or more fatalities per ship year

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 

 

 

 

hz

n j j N j hz N

hz N pr hz fr N fr

1

Risk Model

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Mitigation Analysis Causality Analysis Consequence Analysis

Statistics HAZID Modelling Statistics HAZID Modelling Statistics HAZID Modelling Statutory Assessment SOLAS (A-index) First Principles Analysis

  • transient flooding
  • cross flooding
  • progressive flooding

Systems Availability Systems Availability Systems Availability First Principles Analysis

  • transient flooding
  • cross flooding
  • progressive flooding

Time to untenable conditions First Principles Analysis

  • fire/smoke propagation

Statutory Assessment SOLAS ChII

collision grounding fire

Time to Capsize Time to capsize

Flooding Survivability Analysis

Evacuation and Rescue Evacuation and Rescue Evacuation and Rescue

Safe Return to Port / Casualty Threshold Safety Level

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  • Statutory Assessment

– Compliance with SOLAS 2009 (probabilistic rules) – Optimisation of watertight subdivision

  • Flooding Risk Analysis

– Frequency – Consequences

  • Time to Capsize

– Analytical and performance-based approaches – Vulnerability assessment (as designed / as operated)

  • Time to Abandon Ship

– Assembly and evacuation performance

  • Evaluation of casualty threshold / return to port / safety level

– Probabilistic approach; link to system availability post-casualty

Flooding Survivability Analysis

100’s of Compartments, 1000’s of damage scenarios

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A/R Attained/Required Index of Subdivision j loading condition (draught) under consideration J number of loading conditions considered i compartment or group of compartments under consideration for each j I all feasible flooding scenarios (single compartments or groups of adjacent compartments) for each j w probability mass function of the loading conditions (.4, .4, .2) pi probability mass function of the extent of flooding si probability of surviving the flooding scenarios under consideration at a given j

^ 1 1

. . ; A R ( )

J I j i ij j i

A w p s A E s

 

   

 

Flooding Survivability Analysis

Probabilistic Concept of Ship Subdivision

www.safety-at-sea.co.uk

Optimisation of the watertight subdivision:

– Parametric model – Objective is to achieve high subdivision (A) index whilst accommodating other performance and functional requirements:

  • Minimum weight, maximum capacity
  • Layout constrains (e.g. machinery, MFBs)
  • Service flows, escape routes
  • Tank arrangement
  • Systems location

– Iterative process

Flooding Survivability Analysis

Statutory Assessment – Platfrom Optimisation

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Bulkhead location fixed Deck or Bulkhead location not fixed (possibly removed) Cargo Stores area in the lower hold

Fixed bulkheadMFB

Flooding Survivability Analysis

Statutory Assessment – Platfrom Optimisation (model)

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Basis Ship R=0.8 Design Variables

  • Height of Fb. deck
  • No., position and

height of bulkheads

  • Double hull

Objectives/Constraints

  • Maximum payload
  • A≥ R

NAPA parametric model 1,000s of designs Optimisation Modelling Specification Layout Parametric Model Input Optimisation Problem Setup Internal Layout Optimisation Basis Platform Design Filtering Outcome Consultation Genetic Algorithm 9 Acceptable Designs (A≥0.8)

Flooding Survivability Analysis

Statutory Assessment – Platfrom Optimisation (process)

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0.91 0.915 0.92 0.925 0.93 0.935 0.94 0.945 0.95 0.955 200 400 600 800 1000 1200

Feasible Designs Pareto-optimal Designs

Flooding Survivability Analysis

Statutory Assessment – Platfrom Optimisation (designs)

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A=0.717

19 blhds

Flooding Survivability Analysis

Concept Design Example – Basis Ship

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11 blhd IVSTM 1.5m / D3

A=0.932

Flooding Survivability Analysis

Concept Design Example – Design Alternative 1

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15 blhd ivsTM 1.5m D2/3

A=0.903

Flooding Survivability Analysis

Concept Design Example – Design Alternative 2

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No bulkheads Height of Subdivision Deck A index Basis Ship 19 D2 / D3 0.717 Alternative1 11 D3 up to D3 1.5m 0.932 Alternative2 15 / relocated D2 / D3 up to D2 1.5m 0.903 IVS TM n/a

Flooding Survivability Analysis

Concept Design Example – Summary

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Flooding Risk Analysis

Frequency Analysis (Historical Data)

0.002 0.004 0.006 0.008 0.01 0.012 0.014

fire grounding collision

Frequency per Ship Year

Source: DNV

Frequency of event occurrence

1.148 E-3 1/sy

 

1 hz

fr hz FSA Cruise Ships (SAFEDOR, FSA, 2007): 1 event every 871 ship years

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Flooding Risk Analysis

Consequence Analysis

 

 

  

   

3 , , 1 i n k k j i k n j j i N

Hs flood

N c e p w hz N pr

 

   

 

 

|

| 30 , , , , , ,

ln 30

fail j

t N fail j i j k i j k i j k

t N c N               

 

 

 

 

 

1 1 1

hz N pr hz fr hz N pr hz fr N fr

N hz n j j N j hz N

hz

   

   

max

N N i N N

i fr N F

 

max

1 N i N PLL

i F Risk

Geometry Loading Sea State Flooding extent 1.148E-3 [1/sy] Assembly Abandonment

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Flooding Risk Analysis

Consequence Analysis (Impact on Human Life)

max

N

cap

t t

 

t Nevac

 

t N fail

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Collision

  • Route
  • Crew
  • Navigation
  • Bridge

Hull breach

  • Crashworthiness

Stability failure

  • Geometry (hull & GA)
  • Loading
  • Sea State

Muster failure

  • Crew procedures
  • Layout

Abandon failure

  • LSA

Loss Scenario Flooding

… time to capsize

www.safety-at-sea.co.uk

Time to capsize

Accidents evidence

  • 16 hours
  • 2 hours
  • 15-30 minutes
  • 2 minutes
  • Rapidly !
  • 1 minute
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The time to capsize, given hull breach took place, is a random variable, and therefore, only known as a distribution, determined through probability methods

Loading Sea State Damage characteristics

  • collision/grounding

Governing Parameters

Also Random Variables

Time to Capsize

www.safety-at-sea.co.uk

UK MCA (1996, 1999, 2002, 2010) NEREUS (1999-2003) / HARDER (1999-2003) SAFEDOR (2005-2007) FLOODSTAND; GOALDS; EMSA (Ongoing)

Time to Capsize– Method 1

Inference Model (UGD) – Collision

   

  

   

3 , , i n k cap k j i k n j j i cap

Hs flood

t c e p w t p

      30

, , , , , ,

ln /30

cap

t i j k cap i j k i j k

c t     

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Scenario={displ, KG, damage, Hs}

probability that vessel capsizes within 1 hour if collision takes place

Time to Capsize – Method 1

Inference at Scenario Level – Collision

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40,000 scenarios

probability that vessel capsizes within 3 hours if collision takes place Probability that vessel survives for 3 hours if collision takes place.

Time to Capsize– Method 1

Inference at Ship Level – Collision

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Side View Deck View

Flooding Risk Analysis

Time to Capsize – Ro-Pax

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Flooding Risk Analysis

Time to Capsize – Cruise Ships

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Flooding Risk Analysis

Time to Capsize – Cruise Ships

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Collision Water ingress? yes no Damage case Case i=1 Case i=2 Case i=k Case i=342 Outcome t(i) t(2) t(k) t(342) Model tests Minor incident Vessel unable to survive for 3h Vessel survives for at least 3h (t) Implication Numerical simulations Performance-based evaluation and verification t = time to capsize

Time to Capsize – Method 2

Performance-Based – Monte Carlo Simulation

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Random Variables (MC sampling) Damage characteristics:

  • Location
  • Length
  • Penetration
  • Height

width  grounding Environment (Hs, TP) Loading condition

Time to Capsize– Method 2

MC Simulation – Selection of Flooding Scenarios (Collision/Grounding)

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Time to Capsize– Method 2

Monte Carlo Simulation – Collision

380 scenarios set-up

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30% of possible collision scenarios would lead to capsize within 30 min. 14% of possible collision scenarios would lead to capsize within 30 min. Analytical estimates of time to capsize based on SOLAS 2009 s- factor agree reasonably well with results from numerical simulations

Time to Capsize– Methods 1&2

Typical Results (Ro-Pax) – Collision

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Evacuation and Rescue Analysis

The Evacuation Process – Time to Abandon Ship

Manning of embarkation station Preparation

  • f lifeboat for

embarkation Embarkation (by pax) Launching of Survival Craft Embarkation completed Decision to Assembly Boat casts

  • ff

Waiting for Rescue Assembly Passengers Assembly completed

casualty

Ship Lifeboats

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The Concept of Evacuability

E=f{env,d,r(t),s[evacplan,crew,mii(g,y,hci)];t}

E

Environment (env) Awareness Time (r) Speed (s) Distribution (d)

  • Geometry
  • Topology
  • Semantics
  • Scenario
  • Initial Reaction Time
  • In-situ Reaction Time
  • Gender
  • Age
  • Mobility Impairment
  • Ship Motions
  • Well-Being
  • Location of People

Crew

  • Controlling Spaces
  • Searching
  • Reducing Lost Pax
  • Re-routing

www.safety-at-sea.co.uk

Evacuation and Rescue Analysis

The Evi Model

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Inaccessibility  Ship motions  Deck inclination 

Flooding will make some areas/routes inaccessible Dynamic motion affects peoples’ orientation and movement capabilities Asymmetric flooding will heel the ship, making walking difficult

Evacuation and Rescue Analysis

Flooding Hazards

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Inaccessibility Ship motions Deck inclination

V

Moving Vehicle If d. inclination ≥ 20 deg  v=0 m/s If water depth ≥ 1m  v=0 m/s ? ? ?

Evacuation and Rescue Analysis

Effect of Flooding Hazards

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Evacuation and Rescue Analysis

Effect of Flooding Hazards

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50 1 00 1 50 2 00 2 50 3 00 3 50 4 00 10 0 2 0 0 30 0 4 0 0 5 00

tim e (s ) No people in assembly station

Progressive flooding scenario Intact vessel scenario

  • 5
5 10 15 20 25 50 100 150 200 250 300 350 400 450 500 roll angle (deg)

50 1 00 1 50 2 00 2 50 3 00 3 50 4 00 10 0 2 0 0 30 0 4 0 0 5 00

tim e (s ) No people in assembly station

Progressive flooding scenario Intact vessel scenario

  • 5
5 10 15 20 25 50 100 150 200 250 300 350 400 450 500 roll angle (deg)

www.safety-at-sea.co.uk

Statutory requirements – Optimum compliance with any damage stability requirements (e.g. SOLAS 2009) Safety objectives (beyond statutory requirements) – Probability of survival beyond [3] hours in all relevant collision and grounding scenarios – Identification and rectification of vulnerabilities to flooding (relevant collision and grounding scenarios) – Basis for safe return to port capability

Flooding Survivability Analysis

Outcomes

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Presentation Outline

  • Recent Developments in Ship Safety: Goal-

Based Approaches and Risk-Based Design

  • Safety Level (Total Risk) Modelling

Flooding Survivability Analysis Fire Safety Analysis Post-Accident Systems Availability Analysis Evacuation and Rescue Analysis

  • Concluding Remarks

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  • A new philosophy on “Design for Safety” and the

development of a Risk-Based Design (RBD) methodology enable ship safety to be dealt with in a systematic and all embracing way by treating safety as an objective in the design process.

  • RBD opens the door to innovation and offers competitive

advantage to the maritime industry by facilitating cost- effective safety; without RBD optimal design solutions are not possible!

  • Adopting a risk-based framework is synonymous with

promoting rational decision making; in this respect, such an approach can support and guide contemporary regulatory developments at IMO, e.g., on Goal-Based Standards.

Concluding Remarks

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Design for Safety

Risk-Based Ship Design

Dr Dimitris Konovessis Naval Architecture and Marine Engineering MJB Technical Talk 28 March 2013