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Rogue Waves 2004. Ship design rules and regulations – an overview of major themes Gil-Yong Han Int’l Association of Classification Societies. An overview of major themes. Risk-Based Approach. IACS Common Structural Rules. IMO Goal-Based Standards. * Freak Waves. Role of IACS. SETTING - PowerPoint PPT Presentation
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Rogue Waves 2004Rogue Waves 2004
Ship design rules and regulations – an
overview of major themes
Gil-Yong Han
Int’l Association of Classification Societies
An overview of major themesAn overview of major themes
IMO Goal-Based
Standards
IACS Common Structural Rules
* Freak Waves
Risk-Based Approach
Role of IACSRole of IACS
•SETTINGSETTING
•IMPLEMENTINGIMPLEMENTING
•MONITORINGMONITORING
RULES’RULES’Hull structure + machinery engineering
What are the class rulesWhat are the class rules
Complying with Class Rules:- Provision of adequate global strength;(ships capable of withstanding still water and wave induced loads
with the specified stress criteria)
- Provision of adequate local strength of individual components
(steel material requirements and scantling formulations are to ensure that ships resist modes of buckling, fatigue, yielding, brittle fracture)
- Rules provide direct calculations procedures for determination of scantlings.
Relation with IMO and flag States
IMO Conventions – Statutory RequirementsSOLAS Convention states that in addition to the Conventions requirements, ships shall be designed, constructed and maintained in compliance with class rule requirements of a classification society which is recognized by the Administrations;
Many of the flag States authorize class societies to apply the IMO Conventions (statutory req.) on their behalf by design appraisals and surveys.
What IACS can not doWhat IACS can not do
A strength of “classification” concept is that the Societies act as independent bodies, giving an independent and unbiased assessment of the status of ship’s hull and machinery;
However, they are not guarantors of the safety as they have no control over how a ship is operated and maintained.
The current regulatory framework – The current regulatory framework – shipping safetyshipping safety
Coastal StateRegulations
Flag StateRegulations
UnderwritingClauses
OperationalProcedures
IndustryStandards
ClassificationRules
InternationalConventions &
Regulations
Safety & QualityManagement
Systems
Port StateControls
Chartering &VettingCriteria
Risk-Based Approach in shippingRisk-Based Approach in shipping
In many cases, enhancing the safety rules (structure incl.)
were driven by accidents;
Following high profile accidents (Herald of Free Enterprise,
Exxon Valdez, Piper Alpha), a risk-based approach in ship
design and operation was introduced;
IMO, supported by IACS, recommends FSA to be applied, to
examine potential areas and introduce risk reduction
measures before a tragedy happens.
Bulk Carriers – top priority.
Example: BC Accidents Trend Example: BC Accidents Trend
LOSS OF LIVES
0
20
40
60
80
100
120
140
160
180
200
Years
No
. li
ves l
ost
BULK CARRIER LOSSES
0
5
10
15
20
25
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
Years
No
. vessels
lo
st
0 10 20 30
Collision
Grounding
Structural
Flooding
Machineryfire/explosion
Machinery failure
Cargoloading/unloading
Cargofire/explosion
Cargoshift/capsize
Contact object
Unknown
1993-2001
2002
Source: INTERCARGO Annual Report 2002
ChangesChanges
• A systematic method is put in place to establish the ship safety
rules of the basis of assessment of risks, costs and benefits –
final decisions are now robust and defensible.
• However, this risk-based approach “supplements” the traditional
prescriptive rule-making, allowing variation from prescriptive
rules, provided that the ship (system) risks are maintained at
acceptable levels.
Widespread consensus -
Make ships durable and fit-for purpose
ExpectationsExpectations
Regulatory Regulatory ExpectationExpectation
SafeSafe
Environmentally Environmentally friendly friendly
Easy for inspection Easy for inspection and maintenance and maintenance
Industry Industry ExpectationExpectation
Robust and ReliableRobust and Reliable
Fit for purpose Fit for purpose
User friendlyUser friendly
Goal-Based StandardsGoal-Based Standards
Common RulesCommon Rules
New regulatory frameworkNew regulatory framework
2
3
REGULATION
SELF-REGULATION
Safety objectives
Risk acceptance
criteria
Prescriptive rules
Policies, management systems and best practices
Operational requirements
Objectives Objectives –– Common Structural Common Structural RulesRules
• To eliminate competition between class societies on standards
• To embrace the intentions of the anticipated IMO requirements for Goal-Based Standards for new buildings
• To ensure that a ship meeting these new standards will be recognised by industry as being safe, robust and fit for purpose as would have been required
• To employ the combined experience of all class societies to develop an agreed standard, or set of Rules
IACS Common Structural RulesIACS Common Structural Rules
Net scantling approachNet scantling approach
Buckling and ultimate limit stateBuckling and ultimate limit state of the hull girderof the hull girder
Dynamic loadingDynamic loading
Fatigue lifeFatigue life
Coating lifeCoating life
Transparency and ease of use: Transparency and ease of use: (Under the old rules, the corrosion margin (Under the old rules, the corrosion margin
is given as a percentage, now an absolute min figure corrosion margin)is given as a percentage, now an absolute min figure corrosion margin)
Draft Rules: Draft Rules:
– Fatigue lifeFatigue life [ 25 years ][ 25 years ]
– Coating lifeCoating life [ 10 years ][ 10 years ]
– Corrosion additionsCorrosion additions [ 25 years ][ 25 years ]
– Structural strengthStructural strength intact conditions intact conditions
– Residual strengthResidual strength assumed damagedassumed damaged
Principal new elementsPrincipal new elements
• Net scantling approachNet scantling approach is used throughout the new Rules
• Inclusion of procedures for the assessment of buckling and ultimate limit statebuckling and ultimate limit state of the hull girder
• Inclusion of new methods for describing dynamic dynamic loadingloading
• Inclusion of new methods for determination of the fatigue lifefatigue life
• Development of a Rule format that provides transparency and ease of usetransparency and ease of use
New regulatory frameworkNew regulatory framework
SELF-REGULATION
Safety objectives
Risk acceptance
criteria
Prescriptive rules
Policies, management systems and best practices
Operational requirements
IMO
Goal-Based Standards
Goal-Based FrameworkGoal-Based Framework
Goal Based Safety Objectives
Goal Based Functional Requirements
Goal Based Verification of Compliance Criteria
Tier I
Tier II
Tier III
Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship Operation,
Maintenance, Training, Manning, etc.
Tier V
IACS Common Rules,
Technical Procedures and Guidelines
Tier IV
IMO
Goal B
ase
d S
tand
ard
sIM
O G
oal B
ase
d S
tand
ard
s
GBS represents the top tiers of framework, against which the ships safety is verified both at design and construction stages and during the operation
MechanismMechanism
The mechanism by which the goal-based
standards will be put in place is:
• IMO sets the goal;
• IACS develops class rules that meet the so-
determined goals;
• Industry and IACS develop detailed
guidelines and recommendations for wide
application in practice.
Goal Based Standards + IACS RulesGoal Based Standards + IACS Rules
Optional sub systems and components
Optional sub systems and components
Detailed rule requirementsDetailed rule requirements
Major systems and equipment
Major systems and equipment
Main shipfunctionsMain shipfunctions
Overall objectives
Fun
ctio
nal R
equi
rem
ent
sG
oals
Rul
es
IMO
Class
Example: Safety ObjectivesExample: Safety Objectives
Goal Based Safety Objectives
Goal Based Functional Requirements
Technical Procedures and Guidelines, IACS Common Rules
Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship
Operation, Maintenance, Training, Manning, etc.
Goal Based Verification of Compliance Criteria
Tier I
Tier II
Tier III
Tier IV
Tier V
IMO
Goal B
ase
d S
tand
ard
s
Design LifeDesign Life
Environmental ConditionsEnvironmental Conditions
Structural SafetyStructural Safety
Structural AccessibilityStructural Accessibility
Quality of ConstructionQuality of Construction
Example: Functional RequirementsExample: Functional Requirements
Goal Based Safety Objectives
Goal Based Functional Requirements
Technical Procedures and Guidelines, IACS Common Rules
Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship
Operation, Maintenance, Training, Manning, etc.
Goal Based Verification of Compliance Criteria
Tier I
Tier II
Tier III
Tier IV
Tier V
IMO
Goal B
ase
d S
tand
ard
s
Fatigue LifeFatigue Life
Coating LifeCoating Life
Corrosion AdditionsCorrosion Additions
Strength CriteriaStrength Criteria
Verification CriteriaVerification Criteria
Compliance with the goal-based standards during shipbuildingCompliance with the goal-based standards during shipbuilding
Plan review and approvalPlan review and approval Structural calculationsStructural calculations Surveys during constructionSurveys during construction
Compliance with the goal-based standards on ships-in-serviceCompliance with the goal-based standards on ships-in-service Periodic surveys and thickness measurementsPeriodic surveys and thickness measurements Structural reassessment based on survey and thickness measurementsStructural reassessment based on survey and thickness measurements
DeliverablesDeliverables
• A new complete set of Rule covering the structural requirements for oil tankers and bulk carriers for new construction and for those ships subsequently in service.
• Supporting guidance to amplify the Rules, including the procedures for carrying out direct calculations and for fatigue life assessment.
• Background documents explaining the implicit safety levels, design principles and assumptions on which the Rules are based.
• IACS Common Structural Rules will be in line with the IMO Goal-Based Standards.
Freak Waves FindingsFreak Waves Findings
• Traditionally, this type of waves have been observed Traditionally, this type of waves have been observed
only occasionally under unexpected conditions. only occasionally under unexpected conditions.
However, by virtue of an advance mode of However, by virtue of an advance mode of
measurement and data analysis techniques, such an measurement and data analysis techniques, such an
occurrence is analyzed;occurrence is analyzed;
• Better understanding of the mechanism generating Better understanding of the mechanism generating
such waves has been gained;such waves has been gained;
• The analysis of casualty database and the forecast of The analysis of casualty database and the forecast of
such waves can lead to the development of a such waves can lead to the development of a
mechanism by which masters can be alerted so as to mechanism by which masters can be alerted so as to
enable them to take precautionary action;enable them to take precautionary action;
Freak Waves FindingsFreak Waves Findings
For future study:For future study:
• The design practice is moving a more consistent probablistic The design practice is moving a more consistent probablistic
method, e.g. method, e.g. EExtremes are determined for a given return period xtremes are determined for a given return period
–– expected lifetime of the structure. For consideration in ship expected lifetime of the structure. For consideration in ship
design, the probability of occurrence and also the probability of design, the probability of occurrence and also the probability of
a ship encountering such waves are needed. This involves a a ship encountering such waves are needed. This involves a
rigirous analysis of shipping casualty data. Lack of information rigirous analysis of shipping casualty data. Lack of information
of the core causes of the reported casualties can lead to a of the core causes of the reported casualties can lead to a
misleading or unfounded conclusion. misleading or unfounded conclusion.
• According to the Maxwave study, due to their extreme According to the Maxwave study, due to their extreme
steepness, they last for very short period of time before steepness, they last for very short period of time before
breaking. Hence, the probability of a ship meeting such waves breaking. Hence, the probability of a ship meeting such waves
is even lower that the actual occurrence of freak waves in open is even lower that the actual occurrence of freak waves in open
ocean;ocean;
• SShape of freak wave profiles in space and time including their hape of freak wave profiles in space and time including their
kinematics and ship responses to freak waves are to be kinematics and ship responses to freak waves are to be
documented.documented.
Freak Waves FindingsFreak Waves Findings
• AA distinction between the offshore platform and moving ships distinction between the offshore platform and moving ships
• The validity of a non-linear theory and mathematical model for The validity of a non-linear theory and mathematical model for
freak waves needs be verified. freak waves needs be verified. ENDEND
CSR + GBSCSR + GBS
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