The Korea Shipbuilders’ Association Shipbuilders’ Experience & Feedback on IACS C ommon S tructural R ules

1.Introduction 2.Technical Issues for Oil Tankers 3.Technical Issues for Bulk Carriers 4.Performance of IACS Feedback 5.Software 6.Concluding Remark Contents 1/31

1. Introduction Common Structural Rules (CSR) -Adopted at the End of Effective since April 1, Oil Tankers, Length ≥150m Bulk Carriers, Length ≥ 90m 2/31

1. Introduction Design Experience (Oil Tankers) MRAframax 1Aframax 2SuezmaxVLCC L BP B D Ts DWT50 K105 K115 K165 K317 K Classification LRKR/ABSDNV/ABSDNVKR/ABS 3/31

1. Introduction Design Experience (Bulk Carriers) SupramaxCapesize L BP B D Ts DWT58 K180 K ClassificationKR/LRLR/BV 4/31

2. Technical Issues for Oil Tankers 2.1Weight Increase / Corrosion Addition 2.2Minimum / Maximum Draughts of Abreast Full / Empty Conditions 2.3D/B Floor Thickness Requirement (Bottom Slamming) 2.4Shear Force Correction in way of Bulkhead Stringers 2.5Prescriptive Requirement for Primary Support Member (PSM) 2.6Effect of Toe Grinding on Fatigue Strength 5/31

2. Technical Issues for Oil Tankers 2.1 Weight Increase / Corrosion Addition [Unit : ton] MRAframax 1Aframax 2SuezmaxVLCC Weight Increase +415 (7.5%) +1,000 (9.4%) +940 (8.4%) +1,200 (7.4%) +2,000 (6.0%) Note : Cargo Block Only 6/31

2. Technical Issues for Oil Tankers Note: Design Corrosion Addition of CSR Received a letter from an engineering company ; your hull (1997) excellent conditionvirtually no corrosion another shipyard’stanker (1996) 2mmon the deck platelittle or no wastage “… preparing a bid for an FPSO to be converted from a 1996 DH VLCC … In our search for candidate tankers we looked closely at your hull (1997) and found it in excellent condition. Ballast tank coatings, cargo tank under deck coatings, and tank bottom coatings are still in excellent condition so there is virtually no corrosion. We looked at another shipyard’s tanker (1996) which was built with no coating under deck in the cargo tanks, and found general wastage around 2mm on the deck plate; there was little or no wastage on uncoated structure (longs, transverse webs) lower in the cargo tanks.” 3mm 3.5mm 4mm 3mm 4.5mm 3.5mm 2.5mm 3mm 7/31

2. Technical Issues for Oil Tankers 2.2 Minimum / Maximum Draughts of Abreast Full / Empty Conditions L. BHD Type Center L.BHD Two(2) L.BHD Rule reference Condition Abreast Full Abreast Empty Abreast Full Abreast Empty Prescriptive0.6 T sc 0.9 T sc 0.6 T sc 0.9 T sc Table FEA Sea0.6 T sc 0.9 T sc 0.8 T sc 0.55 T sc Table B.2.3/ B.2.4 Harbor1/3 T sc T sc 0.7 T sc 0.65 T sc Note : T sc = Scantling Draught 8/31

2. Technical Issues for Oil Tankers ConditionDraught Abreast Full Condition ( l h / L ) T min  ( l h / L ) x T sc But not lesser than heavy ballast arrival condition Abreast Empty Condition ( L / l h ) T max  ( L / l h ) x T sc But not greater than T sc Min./Max. Draught Requirements (Proposed by KOSHIPA) 9/31

2. Technical Issues for Oil Tankers 2.3 D/B Floor Thick. Requirement (Bottom Slamming) 42mm (HT32 ) By Prescriptive Req. 42mm(HT32) t mean = 65 Mpa < 164 Mpa (Criteria) 40% ONLY 10/31

2. Technical Issues for Oil Tankers f dist lesser - Coefficient f dist must be lesser, since floor length is short. stiffness of bottomlongitudinals -Effect on stiffness of bottom longitudinals is necessary. f dist f btm-lg Prescriptive Requirement ? 11/31

2. Technical Issues for Oil Tankers 2.4 Shear Force Correction i.w.o. Bulkhead Stringers POSITION Max. Stress Stress Criteria Deviation Below No.1 STR. 160 Mpa 188 Mpa - 15 % Below No.2 STR. 161 Mpa 188 Mpa - 14 % Below No.3 STR. 220 Mpa 252 Mpa - 13 % 26mm (HT32 ) By Prescriptive Req. 28mm (mold ) By Prescriptive Req. 28mm (mild ) By Prescriptive Req. O.T.BHD No.1STR. No.2STR. No.3STR. 12/31

2. Technical Issues for Oil Tankers Prescriptive Requirement FE Analysis ? ? ? 13/31

2. Technical Issues for Oil Tankers 2.5 Prescriptive Requirement for Primary Support Member (PSM) CSR specifies as follows; prescriptive requirements FE cargo tank structural analysis “The section modulus and/or shear area of a primary support member and/or the cross sectional area of a primary support member and a cross tie may be reduced to 85% of the prescriptive requirements provided that the reduced scantlings comply with the FE cargo tank structural analysis” 14/31

2. Technical Issues for Oil Tankers simple formula with unclear assumptions Subject requirement is based on simple formula with unclear assumptions, which can be dealt with by FEA properly and transparently. Prescriptive Requirement D = 0.2 l bdg-dt D = 0.13 l bdg-dt Z = 1000 M C σ yield FE Analysis 15/31

2. Technical Issues for Oil Tankers simple formula with unclear assumptions Subject requirement is based on simple formula with unclear assumptions, which can be dealt with by FEA properly and transparently. Prescriptive Requirement D = 0.2 l bdg-dt D = 0.13 l bdg-dt Z = 1000 M C σ yield FE Analysis 16/31

2. Technical Issues for Oil Tankers 2.6 Effect of Toe Grinding on Fatigue Strength CSR specifies as follows; should not be taken into consideration at the design stage is to be greater than 17 years excluding grinding effects “The benefits of weld toe grinding should not be taken into consideration at the design stage. However, an exception may be made for the weld connection between the hopper plate and inner bottom if the required design fatigue life can not be satisfied by means of practical design options such as increasing local thickness, extending weld leg length and modifying local geometry. The calculated fatigue life is to be greater than 17 years excluding grinding effects.” 17/31

2. Technical Issues for Oil Tankers KOSHIPA carried out fatigue experiment & analysis with a lot of test specimens. 18/31

3. Technical Issues for Bulk carriers 3.1Weight Increase / Corrosion Addition 3.2Hot Spot Stress for Fatigue Strength Assessment 3.3Effect of Toe Grinding on Fatigue Strength 19/31

3. Technical Issues for Bulk carriers 3.1 Weight Increase / Corrosion Addition [Unit : ton] SupramaxCapesize Weight Increase +460 (8.2%) +2,200 (12.6%) Note : Cargo Block Only 20/31

3. Technical Issues for Bulk carriers Note : Design Corrosion Addition of CSR 5.5mm 6.5mm 5.5mm 4.0mm 3.5mm 4.5mm 5.0mm 3.5mm 4.0mm 3.5mm 3.0mm 4.0mm 21/31

3.2 Hot Spot Stress for Fatigue Strength Assessment 3. Technical Issues for Bulk carriers  l Hotspot Stress = l x Extrapolated Stress 22/31

3. Technical Issues for Bulk carriers 0.5t 1.5t 1.0 s 0.8 s : Extrapolated Stress Hotspot Stress ? t 23/31

3.3 Effect of Toe Grinding on Fatigue Strength 3. Technical Issues for Bulk carriers NOT Mentioned 24/31

4. Performance of IACS feedback IACS CSR Maintenance Structure ? 25/31

4. Performance of IACS feedback 4.1 Time Required for Reply by IACS Hull Panel SubjectShip Type Issued to IACS Received Reply by Shipyard Duration Effect of Toe Grinding on Fatigue Strength Oil Tankers Not Yet > 4 months Bottom Forward Draught Oil Tankers weeks Usage Factor for Crosstie Oil Tankers (SAJ) (KOSHIPA) Not Yet Not Yet > 5 months T.B Spacing on Enlarged LongL.(PMA) Oil Tankers Not Yet Not Yet > 3 months Stress Increase Factor for Longls i.w.o BHD. for Fatigue Oil Tankers 07.7 Not Yet Not Yet > 2 months 26/31

4.2 Interpretation from Each Classification Classification Item Ship Type ABCD Is hull girder strength check necessary for flooding case for IACS UR S25 ? Bulk CarriersYES?YESNO Is a certain portion of dynamic load necessary for non-flooda ble empty holds in port ? Bulk CarriersNONOYESNO 4. Performance of IACS feedback 27/31

5. Software incomplete -Computational Softwares are incomplete yet. inconsistency -There is inconsistency between results of respective Classification Societies so far.  The result of any other Class’ software (IACS) must be accepted for drawing in due time approval in due time. 28/31

6. Concluding Remark welcomed in principle CSR is welcomed in principle because ; high technology -It utilizes high technology such as computerized calculation, introduction of dynamic loading and ultimate strength. only one (1) -Shipbuilders need to concentrate only one (1) set rule. 29/31

6. Concluding Remark However, NOTtransparent / rational -CSR contains several technical subjects, which are NOT transparent / rational. with urgency Hence, those should be reinvestigated and corrected as necessary with urgency. 30/31

6. Concluding Remark Robustness Robustness means not necessarily“Fat Boy”. not necessarily the “Fat Boy”. ? 31/31

Thank You Q & A