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n the early 1970s the Inter- governmental Maritime Consultative Organization (IMCO, the earlier name for IMO) was preparing an international code covering the construction and equipment of ships carrying chemicals in bulk. The nascent gas shipping community, aware of the need for a similar set of harmonised provisions for gas carriers, began to make representations to IMCO.
Up until that point shipowners and shipbuilders had relied on classification society rules to guide their design and construction work. The US Coast Guard (USCG) was a national maritime administration that also played a key role in laying down standards for gas ships. Before a gas carrier could enter a US port, it had to undergo a rigorous inspection by USCG staff and be issued with a Letter of Compliance. Like the class societies, the technical branch of the Coast Guard was struggling to keep pace with the rich variety of ship and containment system designs being introduced into the vibrant new gas carrier market.
IMCO, too, realised there was a need for a unified approach and in September 1971 the first meeting was held of a Ship Design Sub-committee ad hoc working group tasked with defining the general format and scope of the proposed gas code, including the type of ships to be covered. The working group, under the chairmanship of the USCG’s Bob Lakey, continued its deliberations for four years, until 1975.
Progress was facilitated by the class
societies agreeing to work together, under the auspices of the International Association of Classification Societies (IACS), to help prepare universally agreed code chapters on cargo containment, cargo handling and materials of construction. The societies had done the early work in developing gas carrier design and construction criteria and in helping those bold shipowners launching pioneering projects. It was essential for IMCO and its efforts to develop a harmonised code to have the societies onside and speaking with a common voice.
The Organization’s work was also supported by industry associations and technical bodies and their input was coordinated through the maritime administrations of certain IMCO member states. For example, the membership of a new USCG group that was to eventually become the Chemical Transportation Advisory Committee (CTAC) included a vast range of organisations, not least the American Gas Association (AGA) and the Society of Naval Architects and Marine Engineers (SNAME). The International Chamber of Shipping (ICS) and the UK Chamber of Shipping channelled their contributions to the IMCO deliberations via the UK Department of Trade.
Drafting work on the code was completed and a text agreed at an October 1974 meeting of the ad hoc working group. This set the scene for the adoption, at IMCO’s Ninth Assembly in November 1975, of the
Code for the Construction and Equipment
of Ships Carrying Liquefied Gases in Bulk, known as the GC Code. Governments were recommended to incorporate its provisions, which covered new ships built from 1976 onwards, into their national regulations as soon as possible.
To cover ships already in service another instrument, theCode for Existing Ships Carrying Liquefied Gases in Bulk, known as the Existing Ship Code, was introduced within a year of the first code. While mirroring the initial document in many respects, the new code recognised that there were areas where it would be neither easy nor cost-effective to bring existing ships into compliance with the provisions for new ships.
The international regime governing gas carrier construction and equipment has been updated over the years. The GC Code was a voluntary instrument but in 1983 the provisions for new ships were made mandatory with the adoption by IMO, the name for IMCO since 1982, of what was in effect a new code. The provisions of theInternational Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk, popularly known as the International Gas Carrier Code, or IGC Code for short, govern vessels whose keel was laid on or after 30 June 1986.
Over the two decades following its adoption the IGC Code was amended several times. However, during the first decade of the new millennium the pace of change in gas carrier design and equipment accelerated. Shipboard reliquefaction and regasification of LNG
The revised IGC Code provides guidance for gas carriers periodically serving as regasification vessels (FSRUs)
A SIGTTO/GIIGNL commemorative issue LNG shipping at 50I 65I 65
were introduced, as were commercial ship-to-ship transfers of liquefied gases, new propulsion systems, new cargoes, sophisticated automation systems and a greater range of gas carrier sizes. It was clear that the next revision of the Code would require a much more extensive work programme than had previously been the case.
At its 83rd Session in October 2007 IMO’s Maritime Safety Committee (MSC 83) agreed to include in the work programme of the Bulk Liquids and Gases (BLG) Sub-committee a new, high priority work item entitledRevision of the IGC Code. In keeping with the strategic approach IMO is now taking with the development of regulations, the revised Code was to be ‘goal-based’ in its approach.
At its 12th session in February 2008 BLG (BLG 12) agreed to a proposal by the UK that the industry itself conduct the revision, a departure from normal IMO procedure. In fact it was the first time that IMO had allowed industry to draft a document outside the Organization’s direct control.
To initiate the revision of the Code a broad cross-section of industry representatives was brought together to establish a steering committee to oversee the work. The UK chaired the steering committee and SIGTTO provided secretarial support. The steering committee consisted of 19 senior industry representatives and oversaw the work of 10 working groups, each of which examined and revised different sections of the Code. Progress with the revision of the IGC Code was reported back to relevant IMO committees and sub-committees on a regular basis.
The working groups consisted of experts from classification societies, liquefied gas ship operators, shipyards specialising in the construction of liquefied gas ships and designers of ship systems and equipment. This participation translated into a wide range of industry coverage, as follows:
• Owner and operators controlling 51 per cent of the world’s gas carrier capacity • Classification societies with 98.5 per cent
of the gas carrier fleet on their registers • Shipyards responsible for 33 per cent
of the world’s LPGC construction capacity and 44.8 per cent of the world’s LNGC capacity.
A total of 39 working group meetings were held in 14 countries during the 26-month period it took to complete the work of drafting the revised IGC Code. The steering committee met six times to review progress, offer guidance and
direction, and agree on the final draft to be submitted to IMO.
The draft revised Code was received by IMO in November 2010. It then went through various IMO committee and sub- committee reviews before being adopted at MSC 93 in May 2014. It will enter into force on 1 January 2016, with an application date of 1 July 2016. This gap between entry-into-force and application dates is to minimise the effect on existing shipbuilding contracts. In practical terms the revised IGC Code applies to ships with keels laid, or at a similar point of construction, on or after 1 July 2016. It is not to be retroactively applied to the existing fleet of gas carriers.
A number of important changes are included in this new revised edition of the IGC Code. These can be summarised as follows:
1. New IGC product data reporting introduced.
2. Concept of tripartite agreement introduced for carriage of cargoes that fall within the scope of the revised Code but are not specified in Chapter 19 of the Code.
3. Location of cargo tanks changed so that separation of cargo tanks from side shell is increased. Separation is now to be between 0.8m and 2.0m, as a function of the volume of the individual tanks.
4. Provides guidance for gas carriers periodically serving as floating LNG production (FLNG) vessels or floating storage and regasification units (FSRUs).
5. New sections addressing internal turret compartments and associated systems.
6. Provides guidance for limit state design for new containment system designs.
7. New, detailed emergency shutdown (ESD) system requirements. 8. Provides requirements for high-
pressure fuel gas systems and for gas- fired internal combustion engines. 9. Requirements for thermal oxidation of
vapours, which include boilers and gas combustion units (GCUs).
10. Provision for sequential lifting to reduce the amount of vented cargo, as well as a requirement for emergency isolation of pressure relief valves (PRVs).
11. Expands on requirements to prevent backflow in the inert gas system and adds a requirement to monitor the quantity of inert gas flowing into individual insulation spaces. 12. Alignment of electrical installation
requirements with IEC 60092,Electrical installations in ships.
13. Alignment and reference to other applicable IMO codes and guidelines, such as the Fire Safety Systems (FSS) Code.
14. New sections on automation systems and systems integration.
15. Requirements for ventilation systems, vent systems and gas detection systems enhanced.
16. Incorporation of applicable IACS Unified Interpretations, the most significant of which covers justification for permitting filling limits greater than 98 per cent. A maximum filling limit of 99.5 per cent is specified. 17. Requires a Cargo Operations Manual. 18. Adds requirements for new
cargoes. MC/AC
The Existing Ship Code recognises areas where it would be difficult to bring ships built before 1976 into compliance with the provisi ons for newer ships
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