Class societies look to the LNG market and beyond
With LNG well on the way to wide adoption, class societies are securing their place and looking ahead to more new fuels, reports Wendy Laursen.
Korean Register (KR) has been active in LNG fuelled ship construction, providing technical expertise and information on concept design, analysis of cost/pay-back time and relevant safety requirements including risk assessment. Last year, the LNG fuelled passenger ship Econuri was successfully delivered under KR class. The vessel was the first LNG fuelled vessel operating in Korea. Several LNG fuelled tugs are scheduled to be constructed in the near future and are expected to be classed with KR. KR has also played a pivotal role in consulting for LNG ready ships.
For all ships which use an LNG fuel system that stores ignitable gases, there is a risk of fire and explosion. A boiling liquid expanding vapour explosion (BLEVE) is an explosion caused by the rupture of a vessel containing a pressurised liquid above its boiling point. The potential for BLEVE is considered from the initial stage of design, says Mr Kim Chang-wook, vice president of technical division at KR. When transferring LNG, fire and explosion may occur under the conditions that the fuel leaks within LEL~UEL (flammability limits) and the ambient surroundings have an ignition source of approximately 550°C.
“LNG’s relative density to air is light (0.6) and so that the probability of BLEVE occurring outdoors is unlikely. However, for safe LNG bunkering, naval architects should deliberately eliminate the conditions under which a BLEVE might occur. This should include the bunkering procedure as well,” he says. “The possibility of suffering a BLEVE depends on the type of LNG fuel tank used within the LNG fuel system and it is rare for a BLEVE to occur at all except where a fire around an LNG fuel tank rapidly raises the temperature of fuel tank. Many safety systems are fitted to LNG fuel systems to prevent fire and explosions – these are generally thought out at the initial design stage. Examples include insulation treatment, fixed firefighting systems and safety relief valve and emergency vent lines.”
The interest in LNG fuelled ships is increasing significantly in South Korea, and KR was awarded a contract by APEC (Asia Pacific Economic Cooperation) to undertake research focusing on the current application of LNG technologies, associated safety aspects, seaborne trade statistics and best practice. Results will be shared with APEC member economies to help narrow the technology gap between countries.
“By taking charge of major governmental projects such as ‘Development of Technology for Floating Offshore LNG Bunkering System’, KR strives to make a technological contribution to the establishment of LNG fuel infrastructure and provide a variety of support (technical solution & feasibility study) to countries such as Indonesia that have a high interest in constructing LNG infrastructure but have not yet secured sufficient relevant technology,” says Mr Kim.
ABS is providing classification services for two LNG-powered containership newbuilding projects, as well as for a series of LNG fuelled OSVs and ethane/ethylene carriers. Already in the construction phase are two LNG-powered containerships for TOTE of the United States, while still in the design phase is a project to class two small containerships for GNS/Nordic Hamburg of Germany. In addition, ABS is providing classification services to a conversion project for TOTE on two ORCA class trailer ships and a pilot project for converting a Staten Island ferry to LNG propulsion.
“From a class perspective one of main challenges of the technology is that the design approach is risk-based and conceptual, which brings it into new territory for some designers who are not familiar with LNG,” says Sean Bond, director of global gas solutions at ABS. “While particular shipyards have LNG teams and generally years of experience in LNG carriers, many designers have never worked with gas and we are putting a lot of advice and support into helping them understand the issues.
“Some challenges are generic to vessel design and operations, while others are LNG specific so it depends where you begin the comparison, but the most fundamental challenge is assessing the location of the fuel tanks,” says Mr Bond. “On a tanker there might be space for the tanks on deck in an environment which is already designed to reflect the presence of hazardous materials. On a containership the challenge is finding space for the fuel tanks above or below decks that provides equivalent levels of safety in what is already a congested cargo area. The designer must also consider the potential risks associated with bunkering during cargo operations, if permitted, during which there would be a lot of activity in numerous areas of the ship which need to be accounted for in any safety assessment.”
Containerships are among the early adopters of LNG as their trades involve sailing to and from fixed ports, which enables their operators to have clearer picture of relevant regulatory bodies and available infrastructure. “While the regulatory regime is still evolving, there is a framework that exists for designing and building an LNG-fuelled ship today,” says Bond. “The impact on design of building in advance of mature regulations is mainly related to any desire to be compliant with future design requirements. If a designer makes the decision to anticipate future requirements based on draft regulations, they are free to include specific concepts for their own commercial or operational reasons.
“Another difficulty for designers at present is associated with a lack of standards and compatibility. One of the outcomes of MSC94 is that the level of uncertainty has reduced. That the regulation might change in future is not necessarily a problem depending on the approach of ports to the developing regulations and their application to the early adopters.”
Additional to the IGF Code, MSC 94 approved draft mandatory amendments to Chapters II-1 and II-2 of SOLAS, which contains a reference to the IGF Code, to be adopted at the next session. The session also approved in general the text of the IGF Code and amendments to the International Convention on Training, Certification and Watchkeeping of Seafarers and to the Code of Training, Certification and Watchkeeping of Seafarers in respect of the minimum mandatory requirements to training of crew for ships using gases and other low flashpoint fuels.
“The IGF Code, the requirements of which will be mandatory, includes basically the requirements of advice status IMO Resolution MSC.285(86) Interim Guidelines on Safety for Natural Gas-Fuelled Engine Installations in Ships,” says Vladimir Shurpyak, senior principal surveyor at the Russian Register of Shipping (RS) machinery department. “Upon this resolution RS has developed and implemented its requirements for gas-fuelled ships. In the RS rules of 2015 these requirements will make a new Chapter in Part XVII.”
Compliance enables the assignment of distinguishing mark GFS, applicable to gas-fuelled ships.
“The key distinction of the new code from the IMO Resolution MSC.285(86), besides its mandatory nature, is a possibility to use not only natural gas (methane), but also other gases including those that are denser than air (propane, ethane, etc) as well as low flashpoint liquids,” says Mr Shurpyak. “In the nearest future after the final approval of the Code, it is planned to supplement the RS rules with the new provisions regarding the possibility to use liquid low flashpoint fuels. The implementation of new requirements will open new horizons for shipowners.”
The problem for early adopters of new fuels is a lack of experience to understand the operational efficiency and limitations, and the lack of an accepted safety framework. According to Dino Cervetto, head of technical services, RINA Services, the process of technology qualification will overcome these issues.
“It is perfectly feasible that ships and generating plant could be powered by methanol, ethane, DME (di-methyl-ether), synthetic diesel, hydrogen or bio fuels,” he explains. “They would all help address SOx and NOx emission concerns and probable future requirements but there are safety issues with the LPG fuels, sustainability concerns with the biofuels and hydrogen so far is only contemplated for fuel cell applications. Before anyone can start to use these fuels there are a number of issues to be addressed. That’s where our technology qualification process would provide the framework to help guide these new fuel technologies into commercial use.”
Technology qualification (TQ) is a process of verification that the novel technology meets the specified requirements for its intended service while guaranteeing an adequate level of safety. “For alternative fuels we have to answer these four questions,” says Mr Cervetto. “Are engines ready to accept new fuels? Are relevant safety issues being considered? What about availability and prices? What’s the impact on logistics?”
Market analysis will answer the last two questions, but manufacturers, shipyards and shipowners will need to rely on a TQ process to answer the questions of technical readiness and safety. The lack of specific regulation for alternative fuels means any new project would need an IMO-approved alternative design dossier to be produced and accepted by the flag state. The safety-related TQ process with its risk assessment would be the core of that.
“New fuels, like any novel technologies, are generally not adequately covered by established codes and procedures, so they present new challenges on a continuous basis, and their development moves faster than the regulators can keep up. Witness how the IGF Code has lagged behind LNG-fuelled engines being adopted,” says Mr Cervetto. “TQ can show the fuels to be safe using an ad-hoc, rational approach. TQ is flexible and reliable enough to address safety of operation, reliability of the novel technology equipment, maintainability of the system, performance and fitness for purpose.”
TQ is achieved through a systematic and documented process of qualification that typically includes examination of the design, risk assessment, engineering analyses and testing programs. The concept of fitness of service covers not only the safety aspects normally addressed by regulatory bodies, but also criteria of reliability, maintainability and performance. This characteristic enables the certification of fitness of service to be particularly appealing to novel technology providers and to the sponsors that are involved in financing the development of such technology.
According to RINA, the shipping industry has learnt the hard way the legal issues related to underperformance of some first-generation water ballast treatment systems. A thorough and comprehensive TQ would have been beneficial to highlight engineering problems up front. RINA has developed a specific Guide for Technology Qualification Processes and has already applied this process to innovative solutions for LNG units. The process is now being applied to alternative fuels.
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