Manufacturers must design systems that are both fit for purpose and flexible enough to be upgraded for future requirements
Speaking at Riviera’s LNG Ship/Shore Interface Conference, Awards and Exhibition in London last November, Manntek LNG Solutions’ business development manager Nigel Edwards noted growth in LNG bunkering has led to the introduction of a number of new standards in LNG bunkering. He added that class societies have announced new bunkering notations and port authorities have unveiled their own requirements.
“We are seeing this as a challenge as to how we design and manufacture the systems,” said Mr Edwards. He explained systems must be designed and manufactured that are fit for purpose, but also are futureproof. “We have to make sure that we manufacture flexibility to improve, upgrade and change the design of systems,” he said.
An LNG transfer system for ship-to-ship (STS) operations has a dry cryogenic coupling (DCC), cryogenic breakaway coupling (CBC), powered emergency release coupling (PERC), LNG transfer hose, high pressure nitrogen (HPN2) power unit and an ESD 1 and 2 system, which is a vessel separation system that uses two wires for ship drift control.
STS operations are governed by strict international safety standards, requiring the LNG bunker vessel to comply with the IMO International Gas Carrier code for Construction and Equipment for Ships Carrying Liquefied Gas in Bulk (IGC Code). The LNG-fuelled ship being refuelled must comply with the International Code of Safety for Ships using Gas or other Low-Flashpoint Fuels (IGF code) interim guidelines.
More recently, a new standard for dry cryogenic couplings, ISO 21593, was released. ISO 21593 pertains to the design, minimum safety, functional and marking requirements, as well as the interface types and dimensions and testing procedures for dry-disconnect/connect couplings for LNG hose bunkering systems intended for use on LNG bunkering ships, tank trucks and shore-based facilities and other bunkering infrastructures. Manntek designs its dry cryogenic couplings to comply with ISO 18683 and ISO 21593.
The idea behind the new ISO standard is to have all manufacturers manufacture to the same standard. “In theory, said Mr Edwards, “this means we can connect a Manntek system to another manufacturer’s system.” Such uniformity and flexibility would facilitate LNG bunkering operations on a more global basis.
There are few companies that claim to have been in involved in as many LNG bunkering operations as Manntek. Based in Sweden, Manntek LNG Solutions was a pioneer in LNG transfer systems for bunkering in Scandinavia in 2012. Initially, applications were for truck-to-ship transfers, followed by terminal-to ship-transfers. In 2013, Manntek was involved in the first STS undertaken between the first LNG bunker vessel Seagas and the LNG-fuelled cruise ferry Viking Grace in Stockholm, Sweden. Bunkering operations occur daily between Viking Grace and Seagas.
Since that time, Mannetek has supplied 29 bunkering systems, four of which are SIL 2 systems. To date, Manntek’s LNG transfer systems have completed 31,500 bunkering operations, transferring about 2.5M m3 of LNG. Six of the 10 LNG bunkering vessels have Manntek LNG transfer systems.
Mr Edwards also advised that owners looking to invest in newbuild LNG bunker vessels should engage LNG transfer system manufacturers as early as possible: “The system has to integrate into the ship and into the emergency shutdown systems.”
Manufacturing LNG transfer systems in sizes from 2 inches (5.08 cm) to 10 inches (25.4 cm), Manntek has secured orders in 2020 for systems to be installed in nine newbuild bunker vessels, seven of which are certified by DNV GL to be SIL 2 compliant systems.