Common Structural Rules (CSR) for Bulk Carriers · PDF fileThe IACS – Common Structural Rules covers ... result presentation and stress ... for Hatch Covers and Hatch Coamings

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


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


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


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


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

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IACS CSRIndividual society Rules

Requirements

Safety level exceeding any IACS members existing Rules.


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


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


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


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.


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


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)


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


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

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New building In service

Required net thickness

Corrosion addition including owners extra Wastage allowance

Renewal thickness

2.5 year diminution


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



Fatigue check of main frame connection to hopper sloping plating and improved steel grade for bracket and adjacent side plating



Fatigue check of inner bottom plating connection with lower stool and hopper sloping plating



Transverse bulkhead and lower stool

Mandatorystrengthening for grab

loading

Fatigue check of lower stool and corrugated bulkhead connection



IACS UR S21 (Rev. 4) for Hatch Covers and

Hatch Coamings


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.


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


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


Common Structural Rules (CSR) for Bulk Carriers · PDF fileThe IACS – Common Structural Rules covers ... result presentation and stress ... for Hatch Covers and Hatch Coamings

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