common structural rules (csr) for bulk carriers · pdf filethe iacs – common structural...
TRANSCRIPT
Common Structural Rules (CSR) for Bulk Carriers
An Introduction
Version Slide 209 May 2006
Scope of Rule Developments
CSR Bulker Carriers- Complete set of Structural Rules for SSS and DSS Bulk
Carriers- Length greater than or equal to 90m
CSR Oil Tankers- Complete Set of Structural Rules for Double Hull Oil
Tankers- Length greater than or equal to 150m
Version Slide 309 May 2006
Summary of CSRs
Jun 2004 1 Jan 2005
1st Draftavailable to Public
2nd Draft CSR available to Public
30 Sep 200515 Apr 2005
Published15 Jan 2006
CSREffective
1 Apr 2006
CSRAdopted
1 Jan 2006
Industry comments6 months
Industry comments5 months
3rd
Dra
ft C
SR B
ulk
Fina
l Dra
ft C
SR B
ulk
Version Slide 409 May 2006
Major modifications of bulk carriers rules after the first draft
Larger uniform corrosion wastage allowances for transverse bulkheads and side shell in line with 95% probability of non-exceedance (instead of 90%)
Thickness rounding procedure is modified, due to harmonisation between CSR Tank and CSR Bulk
Harmonisation of Ships in Operation requirements between CSR Tank and CSR Bulk
Rewritten FEM procedure: Finite element models are now only three holds models, with modified boundary conditions to provide same results between direct and superposition methods
Modification of loading cases to be considered in Direct strength analysis
Compliance with new SOLAS requirements for flooding of DSS bulk carriers
Torsional loading to be considered for the hatch corners
Mandatory GRAB notation for grab loading and steel coil requirements
Version Slide 509 May 2006
CSR – Expected way forward for IACS Common Structural Rules
Feedbackperiod
2006 2007 2008 2009 2010 2011
Harmonization work within IACS
ImplementationHarmonization plan
Harmonized CSR into force
Long term harmonization
External industry hearing
Version Slide 609 May 2006
What is CSR?
Rules covering structural requirement for Bulk Carriers and Tankers
A Rule set 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 by present rules
Saf
ety
leve
l
IACS CSRIndividual society Rules
Requirements
Safety level exceeding any IACS members existing Rules.
Version Slide 709 May 2006
The IACS – Common Structural Rules covers
IACS Common Structural Rules for Double Hull Oil Tankers L 150m and above
IACS Common Structural Rules for Bulk Carriers L 90m and above
Version Slide 809 May 2006
Why CSR?
To obtain control over the minimum safety level during the operation phase
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
Version Slide 909 May 2006
DNV’s commitment to support the industry
DNV’s well established Nauticus Hull program has undergone a major upgrade to provide efficient support for the new Rules.
An extensive training program has been implemented for all approval units enabling our staff to be well prepared to provide efficient and local support
Offer training programs to designers and yards
Offer assistance and design reviews for the purpose of upgrading existing designs to comply with CSR
Offer pre contract service in general
Version Slide 1009 May 2006
Why software support for the new Rules is so critical
The new rule requirements introduce a radical shift towards morecomputerisation of the rule formulations and structural assessment.
Hence, good software support is critical for any Class to provide timely and rational support to ship-owners as well as designers and shipbuilders. Efficient software contributes to ensure safe design while shortening the design time.
Version Slide 1109 May 2006
Nauticus Hull for CSR Bulk - compartment plan and loads shared among all applications
Easy and efficient to analyse many cross sections in Section Scantlings according to the CSR Bulk prescriptive rules:
Hull girder requirements
H-ULS (hull girder ultimate capacity)
Yielding- Local pressures - Intact and flooding
Buckling- DIN Standard
Steel coil- Line loads
Grab loading
Minimum scantlings
Version Slide 1209 May 2006
Nauticus Hull CSR Bulk - Direct Strength Analysis, FEA
New Workflow Manager
New tool for defining compartment plan and loads
New efficient FE tool that will shorten design time – SESAM GeniE
- Modelling of cargo hold model and local models
- Meshing- Automatic Rule loads import
(interfacing with new compartment and loads tool)
- FE solver integrated – SESAM Sestra
- Integrated Post Processing/Code Checking (Buckling Check, Yield Check and deformation Check)
SESAM Xtract for detailed result presentation and stress evaluation
Other SESAM modules (Submod, Cutres)
Version Slide 1309 May 2006
Does CSR provide any benefits to the industry?
Greater transparency of the technical background to the Rules
All IACS societies will cooperate to maintain a single Rule set
Competition will be focused on service level, i.e. newbuilding and SiO support
The net scantling principle, i.e. the minimum allowable scantlings during the operational lifetime of the vessel is defined as the net scantlings for the newbuilding design
Reduced cost for ship yards by relating to one set of structural Rules only
The intention of the new Rules is to encourage the design and construction of robust tankers and bulk carriers and to eliminate competition on scantlings
The minimum fatigue design life is set to 25 year North Atlantic environment.
The corrosion additions that have been established takes into account the location and the environment to which the structural member’s surface is subjected
Stringent and clarified requirements to critical areas
Version Slide 1409 May 2006
Net scantling approach
Net scantling to be maintained through the ship life
Corrosion addition corresponding to the corrosive environment added on top of the net thickness
Renewal thickness to be identified on drawings at newbuliding stage
Thic
knes
s
New building In service
Required net thickness
Corrosion addition including owners extra Wastage allowance
Renewal thickness
2.5 year diminution
Version Slide 1509 May 2006
Critical areas – Stringent and clarified requirements
Longitudinals in way of the hopper tank at shell are most
exposed to fatigue cracks. CSR require 25 years
operational life in North Atlantic.
Increased safety factor for single side
shell according to Solas XII
Version Slide 1609 May 2006
Critical areas – Stringent and clarified requirements
Fatigue check of main frame connection to hopper sloping plating and improved steel grade for bracket and adjacent side plating
Version Slide 1709 May 2006
Critical areas – Stringent and clarified requirements
Fatigue check of inner bottom plating connection with lower stool and hopper sloping plating
Version Slide 1809 May 2006
Critical areas – Stringent and clarified requirements
Transverse bulkhead and lower stool
Mandatorystrengthening for grab
loading
Fatigue check of lower stool and corrugated bulkhead connection
Version Slide 1909 May 2006
Critical areas – Stringent and clarified requirements
IACS UR S21 (Rev. 4) for Hatch Covers and
Hatch Coamings
Version Slide 2009 May 2006
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.
Version Slide 2109 May 2006
Typical Bulk Carrier– Class notation before CSR
1A1 Bulk Carrier ESP Nauticus(Newbuilding) BC-Aholds 2,4,6 and 8 may be empty
for Bulk Carriers L > 150m designed to carry dry bulk cargoes ofcargo 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.
IB(+) is optional
Version Slide 2209 May 2006
Typical Bulk Carrier– Class notation after CSR
1A1 Bulk Carrier ESP CSR BC-A GRAB(20) holds 2,4,6and 8 may be empty
for Bulk Carriers L > 150m designed to carry dry bulk cargoes ofcargo 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.
GRAB [X] minimum X = 20 t unladen grab, mandatory
Version Slide 2309 May 2006