NEW IGC CODE AND IGF CODE

Transcription

1 NEW IGC CODE AND IGF CODE SAFETY ASPECTS Raffaele Piciocchi Gas Center - Greece SAFETY4SEAS - Athens 1 October 2014

2 Content NEW IGC CODE DRAFT IGF CODE 2

3 The New IGC Code A new IGC Code has been approved by IMO with the RESOLUTION MSC.370(93) (adopted on 22 May 2014) This Code applies to ships whose keels are laid, or which are at a similar stage of construction where: 1. construction identifiable with the ship begins; and 2. assembly of that ship has commenced, comprising at least 50 tonnes or 1% of the estimated mass of all structural material, whichever is less, on or after 1 July

4 IGC Code Rewrite Group Composition 129 participants from 18 countries Classification societies (98.5% of world tonnage) Owners (51% of world gas carrier capacity) Shipyards (33% and 44.8% of world LPG carrier/lng carrier capacity respectively) Equipment manufacturers 10 working groups Designers Consultants 10 working groups Steering group with 16 members ABS participated in this effort with 1 expert in the Steering Committee and 10 experts in the Working Groups. ABS also chaired the Group reviewing Chapter 4 of the IGC Code which deals with design and construction of Cargo Containment systems. Steering group with 16 members 4

5 Drivers To update the IGC Code, written in the early 1970 s, to the technological progresses for the last 40 years and to write a document open to the new incoming technologies. Gas carriers, in particular LNG carriers, have excellent safety records, With the tremendous increase of the gas transportation at sea, with the increase of players in this market, it is essential to assure that these records are maintained even in the future and that measures are taken to extend as far as possible the safety using the collected experience, near misses and new technologies. 5

6 Advanced Tools The new IGC Code introduces new requirements for advanced analysis, including dynamic loads, buckling considerations, crack propagations analysis, detail fatigue analysis, etc. The following is an example of a LNG carrier built in Italy on The vessel The LNG cargo tank The 1970 only available structural analysis tool 6

7 Advanced tools Advanced Analysis What we have and what is to be addressed today. 7

8 Advanced tools Risk Assessment Risk Analysis, according with the new IGC Code is a very important tool to assess new designs, new concepts and also to verify the overall safety to existing designs and practices. A high level guideline on a sound risk analysis process is given in Chapter 1 of the new IGC Code as it follows: 1. Methodology and standard applied 2. Potential scenario variations 3. Validation of risk assessment process 4. Quality System used for the risk assessment process 5. Know-how of persons performing the assessment 6. Distribution system of the results 7. Results validation 8

9 Advanced tools Risk Assessment Identification of risks is to be considered, but not limited to, for ships engaged in the above operations: 1. Fire and explosion 2. Evacuation 3. Extension of hazardous areas 4. Pressurized gas discharge to shore 5. High pressure gas venting 6. Process upset conditions 7. Storage and handling of flammable refrigerants 8. Continuous presence of liquid /vapor cargo outside the containment system 9. Tank over / under pressure 10.Ship to ship cargo transfer 11.Collision during berthing and validation 9

10 Examples of New Requirements Increasing Safety The following slides give a few examples of new requirements of the new IGC Code intended to increase safety. They are just examples and are not intended to give an exhaustive report on all the New IGC Code new requirements. 10

11 Increased Protection of Cargo Tanks Against the Risk of Collision Distance of cargo tanks from side shell has been increased as a function of the individual protected tank volume. 11

12 Increased Protection of Cargo Tanks Against the Risk of Collision d for V c below or equal 1,000 m 3, d = 0.80 m; d for 1,000 m 3 < V c < 5,000 m 3, d = (0.75+ Vc x 0.20/4,000) m; d for 5,000 m 3 V c < 30,000 m 3, d = (0.8 + V c /25,000) m; and d for V c 30,000 m 3, d = 2 m, 12

13 Increased Protection of Cargo Tanks Against the Risk of Collision d for V c below or equal 1,000 m 3, d = 0.80 m; d for 1,000 m 3 < V c < 5,000 m 3, d = (0.75+ Vc x 0.20/4,000) m; d for 5,000 m 3 V c < 30,000 m 3, d = (0.8 + V c /25,000) m; and d for V c 30,000 m 3, d = 2 m, 13

14 Increased Protection of Cargo Tanks Against the Risk of Collision The sketch shows an example on how large is the increase of the minimum distance of the tank from side shell on a single hull medium size full refrigerated type A LPG Carrier. For large single hull LPG carrier having a Volume of 22,500 m 3 The minimum distance Increases to 1.70 m 14

15 Intact and Damage Stability The stability requirements have been extended to cover all possible conditions of the vessels: for instance: 1. Stability during ballast water operation is to be examined 2. Ballast and heel are to be considered during stability operations 3. The stability of the ship in all sea-going conditions and during loading and unloading cargo 15

16 Containment system Specific permissible stresses on Type B tanks with plane surfaces provided Means to monitor N 2 flow required for detecting presence of gases in interbarrier spaces Approval criteria for new containment system concepts outlined Functional requirements Design justification process (Limit State) Model testing 16

17 Crack Length mm Type B Tanks Requirements for design life safety factor and survival time from crack development Acceptance criteria based on crack classification Detectable by leak detection C w = 0.5, time to failure 15 days Detectable only by inspection C w = 0.5, time to failure three times inspection period Detection unassured C w = 0.1, time to failure three times tank life (Critical crack length = 1,000mm) Through crack (Gas detection) Initial crack Years of Ship Operation 17

18 Membrane Tank Fatigue Significant amount of detail added Additional checks carried out for internal tank structures not detectable by continuous monitoring / leak detection Example Undetectable area Some fatigue design events included Thermal insulation cracking, internal structures and their supports, inner hull cracking leading to water ingress 18

19 Type C Tank Fatigue Fatigue in particular cases to be specially considered for low temperature cargoes Pressure vessel codes assume cycling dynamic stresses are low compared to design (membrane) stresses associated with pressure Colder cargoes loaded into type C tanks at near atmospheric pressure may expose components to reversing stresses unexpected by Codes 19

20 Construction Issues Under matched welds defined and recognized Importance of non-metallic joints is recognized Non-metallic to non-metallic Non-metallic to metallic Hull structure tightness testing clarified membrane ships Tightness test mandatory for all cargo tanks prior to installation of the membrane 20

21 Secondary Barrier Testing Existing general requirement tightened Acceptance criteria for secondary barrier defects clarified Defect sizes to be determined related to liquid tightness Detection accuracy of testing method to be understood Test acceptance criteria to be tied to design basis including Effects of thermal/mechanical cyclic loading and prototype test results Above factors to be part of approved testing method 21

22 Piping Systems A new list of basic concepts to be taken into account for the design of cargo handling has been introduced in the new Code 1. Prevention of an abnormal condition escalating to a release of liquid or vapor cargo; 2. The safe collection and disposal of cargo fluids released; 3. Prevention of the formation of flammable mixtures; 4. Prevention of ignition of liquids or gases and vapors released; 5. Limiting the exposure of personnel to fire and other hazards. 22

23 Piping Systems Liquid piping systems are to be designed to withstand the surge pressures. New requirements relative to high pressure piping systems in machinery spaces have been added. New detailed requirements relative to cargo design and arrangements of cargo sampling points introduced 23

24 Gas Combustion Units New Section 7.4 for thermal oxidation Applicable to LNG Cargo vessels only Consists of safety based design requirements Arrangements Features Source: Hamworthy 24

25 System Integration Mitigation of risk for the personnel of for installation to be harmed by the essential safety functions Definition of roles and responsibility for integration of systems Definition of functional requirements of each component and sub-system Risk analysis Prevention that any part of the integrated system be affected by any failure in any part of the system, except the defective part itself Operation of the integrated system to be not less effective than the operations of the stand-alone individual equipment Demonstration of integrity of essential machinery and systems during normal operation and fault condition 25

26 Other Main Changes Filling limits for cargo tanks Criteria provided for maximum filling over 98%V at ref temp. No isolated gas pockets Absolute Max 99.5%V at ref. Use of cargo as fuel Covers high pressure fuel gas systems Introduces requirements for gas fired internal combustion engines Opens the door for fuels other than methane Operating Requirements Expanded requirements for ESD system 26

27 New IGF Code IMO issued on 24 April 2014 a new draft IGF Code. This draft is not mandatory. The IMO MSC is supposed to discuss again the IGF Code in their meeting of mid-november

28 New IGF Code Safety Aspects As already mentioned, Gas Carriers and LNG Carriers, in particular, have excellent safety records compared with other categories of vessels. The main concern about the possible growth of a large number of dual fuel vessels is that the present safety level assured by vessels complying with IGC Code might not be continued with the increase of gas fueled vessels. 28

29 New IGF Code Safety Aspects This concern is mainly coming from the following considerations. Dual fuel vessels are likely to be used everywhere in the world, including very congested areas, restricted areas, close to city and in highly populated areas, rivers, etc. Dual fuel vessels will require a large number of bunkering operations, many will actually be transshipping operations which are potentially dangerous. The lack of knowledgeable, skilled and appropriately trained officers and crew. 29

30 New IGF Code Safety Aspects These concerns are delaying the issuance of the new IGF Code, which drafts have been reviewed several times. While the first draft where less severe that the IGC Code, it appears the some aspects of the latest draft are even more severe than the IGC Code. As an example the minimum distance of the gas tanks from side shell has been increased in the last draft IGF with respect to the requirements of the new IGC Code. Now for dual fuel vessels other than gas carriers it is required a minimum distance similar to the one required by the IGC Code for type 1G vessels, which are vessels intended for toxic products. 30

31 New IGF Code Safety Aspects The last draft of the new IGF Code in addition and alternative to the deterministic method for the determination of the minimum distance, propose also a probabilistic method similar to the one adopted by SOLAS to calculate the damage for the damage stability calculation. However, also the probabilistic method is quite conservative with respect to the deterministic method in the IGC for vessels carrying flammable gases. 31

32 New IGF Code Safety Aspects Considering the many modifications of the draft IGF Codes so far published and some disagreements still existing between certain Administrations on certain requirements of the Code, it is premature at this stage to make a more detailed analysis on the content of the new IGF Code, as many present requirements might be changed in the next couple of months. 32

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