IACS Common Structural Rules

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IACS Common Structural Rules

• Bulk Carriers

MTPNO876 Bulk Carriers and Container Ships 01
March 2006
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What is CSR?

• Rules covering structural requirement for Bulk
  Carriers and Tankers, both newbuilding and in
  service
• A Rule set applied in a systematic manner
  utilising state of the art computational methods
  for more extensive direct calculations
• Vessels built to CSR shall have overall safety of
  the hull structure equivalent to or better than
  that currently achieved in relation to life,
  environment and property
• Safety level exceeding any IACS members existing
  Rules.

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Why CSR?

• To eliminate competition between class societies
  with respect to structural requirements and
  standards
• To employ the combined experience and recourses
  of all IACS societies to develop a single
  standard, or set of Rules
• To ensure that a vessel meeting this new standard
  will be recognised by the industry as being at
  least as safe and robust as would have been
  required by any of the existing Rules
• To fully embrace the intentions of the
  anticipated IMO requirements for goal based new
  construction standards.

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CSR - Benefits to the industry

• Greater transparency of the technical background
  to the Rules
• Reduced cost for ship yards by relating to one
  set of structural Rules only
• All IACS societies will cooperate to maintain a
  single Rule set
• Competition will be focused on service level
  covering
• pre-contract,
• plan approval,
• newbuilding supervision
• Ability to quick and efficient problem solving
  during ship in operation (SIO)
• No competition on scantling requirements and Rule
  standard

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DNV - Ambitions

• To be the best software supplier for CSR. The CSR
  Bulk software will reflect the experienced gained
  by the successful CSR Tank Software already
  recognized by users worldwide.
• To be the preferred discussion partner for
  owners seeking to contract CSR vessels.
• To be the preferred partner for yards and
  designers developing CSR vessels. Introducing
  ship yards and designers world wide to the new
  rules, where among extensive software training
  and rule background explanation are offered.
• To be perceived as the most proactive and problem
  solving class society through genuine interest
  and gained knowledge about owners operational
  challenges.

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IACS Common Structural Rules
IACS Common Structural Rules for Bulk Carriers L
90m and above
IACS Common Structural Rules for Double Hull Oil
Tankers L 150m and above
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DNV CSR Bulk - Implementation schedule
1 Apr 2006
1 Jan 2005
14. Dec 2005
3 Apr 2006
15 Feb 2006
CSR adopted by IACS Council
DNV software test release CSR Bulk carrier Rules
CSR Effective
DNV software release CSR Tanker Rules
DNV offer design review according to CSR
DNV software release CSR Bulk carrier Rules
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CSR - harmonization

• Short term harmonization prior to adoption by
  IACS
• Long term harmonization

Implementation and industry comments
Detailed harmonization plan
Feedback period
Harmonized CSR into force
Harmonization work within IACS
2006
2007
2008
2009
2010
2011
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CSR Bulk - Application

• Applicable for Bulk Carriers with L 90 m signed
  for construction after 1 April 2006
• where
• Bulk Carrier is a sea going self-propelled ship
  which are constructed generally with single deck,
  double bottom, hopper side tanks and with single
  or double side skin construction in cargo length
  area and intended primarily to carry dry cargoes
  in bulk.
• L lt 350 m
• L / B gt 5 m
• B / D lt 2.5 m
• CB 0.6

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CSR Bulk Carrier in general
CSR
Not CSR
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CSR Bulk questions and answers

• If a contract signed prior to 1st of April 2006
  but construction will not commence until 2007?
• Ships or series of ships signed for construction
  prior to 1. of April 2006 is not subject to CSR
  even if the construction is taking place later
  than 1st of April 2006. Such ships will be
  subject to current DNV Rules.
• What if a ship building contract, signed prior to
  1st of April 2006, includes options for
  additional ships, to which rules should the
  optional ships be constructed?
• Options included in contracts signed prior to 1st
  of April 2006 is not subject to CSR if the option
  is exercised within a year of the initial
  contract signing.
• What if a ship building contract, signed before
  1st of April 2006, is amended, to which Rules
  should the additional ships be constructed?
• Amendments is subject to the Rules in force at
  the date of signing the amendment. If the
  amendment is signed on or after 1st of April
  2006, the ships are subject to CSR.
• What about SOLAS XII Additional safety
  measures for bulk carriers requirements which
  come in to force July 2006?
• For a vessel subject to CSR, SOLAS XII is
  automatically covered.
• For vessels not subject to CSR, but subject to
  DNV Bulk Carrier Rules and with keel laying on or
  after 1st of July 2006, the SOLAS XII
  requirements are to be handled separately.

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CSR Bulk questions and answers

• Will vessels complying with DNV
  Nauticus(Newbuilding) meet the criteria of the
  CSR?
• No. For the Nauticus(Newbuilding) design
  parameter is 20 years World Wide while 25 years
  North Atlantic is applied in the CSR. In
  addition, different yielding and buckling
  criteria is applied in CSR.
• Will it be possible to modify an existing DNV
  Nauticus(Newbuilding) approved vessel to comply
  with the new CSR criteria?
• Such modification would most likely enforce
  replacement or modification of key structural
  members. It is unlikely that such modifications
  could be considered economically feasible.
• What would be involved to upgrade and exciting
  CSR sized design to meet the CSR criteria's?
• Based on present experience, an increase in steel
  weight of 2-4 and up to 7-9 is expected
  depending on the original design basis. E.g. a
  IACS URS25 compliant vessel will normally fall
  within the first category.
• DNV is currently cooperation with mayor bulk
  carrier designers to assist in upgrading their
  designs to meet CSR.

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CSR Bulk questions and answers

• Will a design already reviewed and approved as
  meeting the CSR by another IACS member be
  accepted by DNV?
• As the design is already reviewed and approved by
  an IACS member, no significant difference in
  scantlings is expected. However, in order to
  verify such expectation, DNV will carry out full
  plan approval. If discrepancies are revealed this
  will be addressed in the appropriate IACS forum.

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CSR Bulk Class notations

• X1A1 Bulk Carrier ESP CSR BC-A allowed
  combination of specified empty holds
• ? for Bulk Carriers L gt 150m designed to carry
  dry bulk cargoes of cargo density 1.0 t/m3 and
  above with specified holds empty at maximum
  draught. This notation implies that the ship is
  designed for alternate loading.
• maximum cargo density (in t/m3)
• ? if the maximum cargo density is less than 3.0
  t/m3
• GRAB X ? minimum X 20 t unladen grab,
  mandatory

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CSR Bulk Class notations

• X1A1 Bulk Carrier ESP CSR BC-B
• ? for Bulk Carriers L gt 150m designed to carry
  dry bulk cargoes of cargo density 1.0 t/m3 and
  above with all holds loaded . This notation
  implies that the ship is primarily intended for
  homogenous loading.
• maximum cargo density (in t/m3)
• ? if the maximum cargo density is less than 3.0
  t/m3
• GRAB X ? minimum X 20 t unladen grab,
  mandatory

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CSR Bulk Class notations

• X1A1 Bulk Carrier ESP CSR BC-C
• ? for Bulk Carriers L gt 150 m designed to carry
  dry bulk cargoes of cargo density less than 1.0
  t/m3. This notation implies that the ship is
  limited to light cargo in homogenous loading
  condition.
• GRAB X ? optional grab notation

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CSR Bulk Class notations

• X1A1 Bulk Carrier ESP CSR
• ? for Bulk Carriers 90 lt L lt 150.
• These ships have no minimum conditions. They are
  designed according to the loading conditions in
  the loading manual.
• GRAB X ? optional grab notation

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CSR Net scantling approach
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CSR Corrosion additions

• Corrosion addition determined based on the
  environment to which the structural member is
  subjected.
• E.g.
• tc1, exposed to sea water 1.0mm
• tc2, water ballast tank in general 1.2 mm
• treserve, maximum thickness diminution in 2.5
  years 0.5 mm
• Total corrosion addition
• tc Roundup0.5(1.2 1.0) 0.5 3.0 mm

tc2
tc1
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CSR Corrosion additions
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CSR Environmental assumptions

• 25 years design life
• Today the common practice is 20 years
• Resulting in increased corrosion additions
• Slightly higher design loads
• North Atlantic environmental conditions
• Fatigue the damage in North Atlantic is about
  twice the damage of World Wide trading

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Global strength FE Analysis model extent
(Assessment target)
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Global CH model - Criteria

• Yield check
• Buckling check of elementary plate panels
• Shear buckling
• Longitudinal buckling
• Transverse buckling
• Bi-axial buckling
• Relative deflection between the double bottom and
  TBHD

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Typical areas to be refined for yield check

• Typical details to be refined

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Refining method for yield check
EITHER Refined areas can be directly included
in FE model used for the global cargo hold
analysis
OR Detailed stresses in refined areas can be
analysed by separate sub-models
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Fatigue assessment of primary structures
Primary members subject to fatigue strength
assessment

In addition, hatch corners. Stress concentration
factors for hatch corners established by formulas.
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Fatigue assessment of stiffeners

• Connection of stiffeners with web frames and
  transverse bulkhead.
• Stiffeners end connections to be analyzed
• Ordinary stiffeners in double side spaces
• Ordinary stiffeners in upper and lower wing tank
• Ordinary stiffeners in double bottom
• For typical stiffeners end connections tabular
  values for stress concentration factors have been
  established.

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