First-in-class vessels can pose technical challenges to the most experienced shipbuilders, but the lessons learnt can prove invaluable
Clean Jacksonville, a non-self-propelled, steel-hulled bunker barge with a capacity of 2,200 m3 of LNG, was constructed at Conrad Orange shipyard, a subsidiary of Louisiana-based Conrad Industries.
The shipyard provided feedback on the project, which was detailed by GTT North America general manager Aziz Bamik during a seminar in Tokyo last year (see end of article).
Based on a conceptual design by cryogenic cargo containment company GTT, Clean Jacksonville transports LNG from the JAX LNG liquefaction facility on the St Johns River to refuel Tote Maritime Puerto Rico’s 3,100-TEU dual-fuel container ships Perla del Caribe and Isla Bella, which operate from the Port of Jacksonville, Florida to San Juan, Puerto Rico.
Designed to operate in inland waterways, bays, harbours and US coastal waters, the bunker barge has no propulsion machinery and is towed via hawser wire or pushed from the stern and manoeuvred at the hip by a tug, with the ability to be towed at a maximum speed of eight knots on its 1.6 km transit down river. Clean Jacksonville has a length overall of 64.6 m, beam of 14.6 m and draft of 2.6 m. It is compliant with the Jones Act, meaning that it is registered under the US flag, built in US and owned and crewed by US citizens.
Rhode Island-based naval architect and marine engineering firm Bristol Harbor Group (BHGI) was responsible for the design and engineering of the bunker barge and its sister company The Shearer Group, Inc based in Texas provided technical/shipyard support during the construction.
BHGI also served as the regulatory lead and liaison between the regulatory bodies ABS and the US Coast Guard (USCG) and participated in a Hazid/Hazop primary risk assessment workshop, as well as a waterway suitability study and a waterway suitability risk assessment that were the first steps towards obtaining USCG approval.
While Clean Jacksonville is a non-self-propelled vessel, it is still outfitted with all the complex equipment necessary for LNG transport and bunkering. Six Stirling StirLNG-4 cryocoolers can be used to cool down the LNG to manage BOG when necessary. Despite its short route, the bunker barge also has an impressive LNG holding time of more than 27 days.
“Full front-end-engineering design before steel cutting will be beneficial for all future LNG bunkering vessels”
The first such barge built in the US, it is fitted with a single cargo tank with a capacity of 2,200 m3 based on GTT Mark III Flex cargo containment technology. GTT also developed a specially designed bunkering arm to refuel the bunker tanks at a transfer rate of 500 m3/h located on the aft deck of the containerships. The barge has an LNG transfer time is 4.5 hours and it is capable of accepting return vapour from the vessel that is being bunkered.
Beyond its traditional role of designing the cargo containment and other cryogenic elements, GTT adapted and expanded its support services by developing a training simulator to ensure the effective training of the barge crew and the safe and satisfactory execution of the barge commissioning activities and gas trials.
The bunker barge is fitted with a deck-mounted bunker mast system for ship-to-ship fuelling
The concept for the LNG bunker barge was Approved in Principle by class society ABS on 21 March 2014. Conrad Orange acquired all of the equipment and trained its own crew for the installation of the membrane containment system. GTT conducted a technical audit of the shipyard in May 2014, followed by additional training in October at Conrad, GTT in France and major component suppliers in South Korea. A mock-up of the membrane tank was completed in December after only six weeks of fabrication by Conrad’s team.
In January 2015, Conrad Orange signed a license agreement for the GTT membrane technologies. A shipbuilding contract was inked on 25 February 2015. Conrad Orange laid the keel for the steel-hulled barge in September 2015. This led to the start of the cargo containment system engineering and the procurement of the main equipment in April, steel cutting in July and the launching of the barge in February 2016.
Installation of the primary and secondary barriers of the cargo containment system took about eight months to complete, with the tank completed in early January 2017.
The barge was commissioned, with cold tests using nitrogen at Conrad Orange shipyard and gas trials performed at Harvey Gulf International’s bunkering facility in Port Fourchon, Louisiana, which has three x 340 m3 small LNG ISO tanks. Tests were conducted at the facility to examine future operational scenarios including gassing up, cooling down, loading (trucks and via terminal onshore tanks), unloading, warming-up, inerting and aerating.
The bunker barge was loaded with 635 m3 of LNG – a record for the plant – in several parcels due to terminal commercial operations and truck logistics.
Tote took delivery of the bunker barge on 20 August 2018, with the first commercial bunkering on 27 September 2018. The Clean Jacksonville was loaded with 1,500 m3 of LNG for the 3,100-TEI, LNG-fuelled container ship Perla del Caribe. The connection was achieved in about 20 minutes via the bunker mast, with 1,000 m3 of LNG transferred in under four hours.
Mr Bamik joined GTT in 1999 and has served as general manager of wholly-owned subsidiary GTT North America (GTT NA) in Houston since its formation in 2013. He will present on “Feedback on the construction and first year of operation of the first dedicated LNG bunker barge for US marine market” at LNG 19 in Shanghai on 4 April.
Overcoming the odds
Conrad Orange noted several technical challenges in designing and building Clean Jacksonville, including:
• As the first US LNG bunker barge, developing a barge design with assumptions on the regulations and rules that were undefined at that time was difficult.
• Management and coordination of an international project team was a strength, but language and the time zone differences between the team proved challenging.
• The adaptation of a ‘hazardous zones’ definition based on the International Gas Code (IGC) in comparison to the policy letter issued by the US Coast Guard proved difficult and induced many changes.
• Full front-end-engineering design (FEED) before steel cutting will be beneficial for all future LNG bunkering vessels.
• The operating profile of any barge needs to be clearly defined.
• The lack of small-scale LNG equipment available on the market proved challenging.
• LNG systems design and the integration of systems were major challenges, with the overall LNG systems design and approval requiring much more time than anticipated.
• Strong collaboration between all stakeholders including regulators was critical.
• The construction of the membrane tank was the “most straightforward item,” meeting budget and schedule. The membrane tank containment system was completed 20 months prior to delivery.