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DNV GL has developed a new class notation for gas bunker vessels that is designed to ensure safe fuel transfer operations from one ship to another.

In a statement, the company said: "Until now, the development of standards guiding gas fuel transfer operations in ports has lagged behind, as the maritime industry focussed on developing standards for gas-fuelled ships rather than bunkering arrangements. This notation addresses safety concerns in this field and covers gas bunker vessels design [sic] and additional requirements to support the development of gas-fuelled shipping and bunker operations in ports. The rules are flexible and include a variety of gas fuels as well as the configuration of bunker transfer systems."

DNV GL pointed out today that "many port authorities still deem ship-to-ship bunker operations as being too risky and oppose efforts to increase the availability of gas fuels in ports".

In reference to this issue, Yury Ilchenko, Principal Engineer at DNV GL, remarked: "Complying with DNV GL's new class notation increases the acceptance of safe gas fuel bunkering operations by ports and local authorities and puts bunker ship owners in a stronger position in the market."

DNV GL says that flexible ship-to-ship bunkering transfer operations are "an efficient solution" in locations with limited infrastructure and with demands for short turn-over times in ports. DNV GL's new class notation outlines requirements for liquefied gas carriers and barges that are equipped for carrying liquefied gas and supplying it to gas-fuelled ships on a regular basis.

"The class notation covers safety issues on the gas bunker vessel, its gas bunker-related equipment and installations on board. It includes requirements for design, construction and operational procedures with regard to the connection and disconnection of transfer arrangements, bunker transfer and vapour return," explained Ilchenko.

Tougher limits on the sulphur content of marine fuels (0.1 percent) in Emissions Control Areas (ECAs), which entered into force in January 2015, have increased the demand for port infrastructure dedicated to bunkering alternative fuels such as liquefied natural gas (LNG).

From 2020 onwards, vessels sailing in all European waters will need to comply with a 0.5 percent sulphur cap. In addition, the International Maritime Organization's global sulphur limit of 0.5 per cent is expected to come into force in 2020 or 2025, depending on the outcome of a review as to the availability of the required fuel oil.

DNV GL has also developed a GAS READY notation for owners looking to prepare their vessel for a potential conversion to LNG operation at the newbuilding stage. The notation is designed to help owners ensure that their vessels are verifiably in compliance with all safety and operational requirements to meet the applicable global as well as class standards for gas-fuelled operations. It is also designed to support owners in specifying and quantifying the level of investment they need to make.

Image: The world's first ship-to-ship (STS) transfer of LNG between two Q-Flex type ships. The transfer of 211,000 cubic metres of LNG was conducted at anchor in open waters in Singapore. The operation commenced on January 22 and was completed on January 28, 2014.