New guidance and standards are on the way for ship-to-shore interfaces and bunkering of future fuels
The global standards that are being developed for marine loading arms (MLAs) and cryogenic hoses for import, export and bunkering of potentially hazardous liquefied gases were the topic of discussion at Riviera Maritime Media’s New twists on marine loading arms and hoses webinar.
Oil Companies International Marine Forum (OCIMF) engineering adviser Ricardo Martinez said he expects a standard for liquefied hydrogen (LH2) to be published in 2022, under International Standard Organization standard ISO/CD 24132 for ships and marine technology.
The new standards will cover design and testing of marine transfer arms for LH2. The arms are on the cutting edge of technology for marine transfer of cryogenic gas, and developing safety and quality standards for equipment involved in LH2 transfer poses new challenges for the sector. In particular, transfer operations between terminals and ships are tricky procedures due to the need for LH2 to be kept at -250ºC, as Mr Martinez explained.
ISO is working on standards for liquefied hydrogen marine transfer arms just as the first test project is being developed to transport the gas from Australia to Japan.
“The project of transporting LH2 is a demonstration to show it can be transferred to a ship in Australia and from a ship to a terminal in Japan,” said Mr Martinez, adding “there could be (LH2) bunkering activity in the future.”
Gutteling Group managing director Sander Verweij said development of LH2 marine transfer hoses was happening at a slow pace. “It is challenging,” he said. “There is very little knowledge on these hoses and getting people with experience is difficult.”
Mr Martinez agreed it was challenging to find enginners with knowledge of hoses and MLAs for hydrogen as the “engineering is technically difficult”.
“It is a chicken and egg situation,” he said, underscoring that knowledge would be developed through continued trials, such as the one in Japan.
“They have not yet developed the MLA or ship-to-shore interfaces," Mr Martinez said. When the interfaces are developed, detail about their safe operation would be fed into the ISO standards for MLAs and hoses.
Mr Martinez said he expects the Japanese demonstration project is “being built on best knowledge” of the existing technology, albeit with limited experience.
“This will be the starting point” for future projects, standards and guidance and “getting experience of operating ships and MLAs” for LH2.
“MLA documentation will grow to keep pace of this, to strengthen the guidance and standards over time,” said Mr Martinez.
Attendees of the webinar were asked a series of poll questions to ascertain their thoughts on various issues within MLA development, safety and design.
In one poll they were asked what they thought were the biggest future growth area of MLAs. 51% of those responding said LNG bunkering, 38% thought hydrogen, 8% voted for offshore and just 3% for high pressure natural gas.
In his presentation, Mr Martinez outlined the latest OCIMF guidance publication, fourth edition of Design and Construction Specifications for Marine Loading Arms. He said the publication was aimed at marine terminal owners and operators procuring MLAs, contractors working on behalf of owners, MLA vendors, classification societies and other quality assurance organisations, regulators, shipbuilders and fabricators.
“We are raising awareness through publications and information papers about MLAs,” Mr Martinez said. This comes as there are more than 5,000 MLAs working in terminals of various types worldwide.
OCIMF’s publication covers MLAs for oil and oil products, liquefied gases – including LNG, LPG, ammonia and liquid ethylene – high-pressure natural gas, chemicals and vapour return.
“It is the definitive guide to MLA construction and specification,” he continued, “covering topics such as applications, variability, operating envelopes, products transferred, servicing, manifold spacing, jetty, piping layouts and arm styles.”
Within the publication is an overview of MLAs and their features, specification, design and build processes, MLA design, protection and safety, hydraulic and electrical control systems, quality assurance and control, prototype manufacturing and acceptance tests.
The protection and safety system chapter “addresses the design philosophy and design basis of MLAs and their associated operating, safety and control systems,” said Mr Martinez.
This includes guidance on deciding the level of monitoring and protection, MLA alarm and monitoring systems, emergency release and shutdown systems, control system failure mode analysis and safety integrity levels.
There is also a chapter covering specific design issues related to specialist MLAs, including offshore MLAs and those for marine bunkering and high-pressure natural gas.
OCIMF’s guidance also includes specification tables, which “define information that should be provided by the vendor for the installation, maintenance and safe operation of the MLAs,” said Mr Martinez.
There were good levels or awareness among webinar attendees as 80% said they knew there were ISO standards for marine transfer arms in a poll.
In another poll question, attendees were asked what the biggest industry wide MLA challenge was, with 45% saying it was applying any new guidance to existing MLAs. 32% thought it was MLA condition monitoring and 23% voted for understanding requirements.
Gutteling’s Mr Verweij explained the importance of standards and guidance for marine transfer hoses during his presentation, highlighting European standard EN 1474-II: 2020.The standard covers installation and equipment for LNG, including design and testing of marine transfer systems, with part two specifically covering design and testing of transfer hoses.
“EN 1474-II: 2020 requires more extensive testing that leads to more reliable and safe transfer solutions,” said Mr Verweij. “More tests were added, including a creep test, which is important for hose lifetime characteristics.”
Mr Verweij looked at one specific element in the European standards covering liquid freeing and purging. There are different variables to consider including the human factor, weather conditions, LNG composition and temperature, nitrogen gas supply, draining method, timing limits and opening and closing of valves.
“When liquid is pooled in a hose and the system is started up, this pool – due to wave formation on the pool – can be pushed as a slug with high velocity through the hose, leaving some liquid behind,” said Mr Verweij.
“This may lead to very high forces on bends, which may lead to high shear forces at the wall,” he continued. This could be 0.1 bar/m. “This may lead to very high forces on other components in the system.”
To avoid issues during liquid freeing and purging, operators should avoid LNG slugs in gas, rapid phase transition, high gas flow velocities, expansion waves in the system and pressure peaks.
To conclude, Mr Verweij presented future steps in hose design and development. These steps include designing hoses with pressures upgraded to 21 bar for hoses up to 25-cm in diameter, as well as hoses delivered for continuous LNG transfers for ship-shore interfaces of up to 40.6-cm in diameter, although these hoses have not yet been certified.
Manufacturers are fabricating longer hose lines, up to 50 m, and LNG hoses with additional thermal insulation.
Webinar attendees were asked poll questions covering marine transfer hoses. In one poll 77% agreed composite hoses are an alternative for loading arms, and 23% disagreed.
Attendees were asked if existing standards for safe operations with hoses are good enough. 73% of those responding said they were adequate, but could go further. 19% thought they were “spot on”, 5% said they were insufficient and 3% thought they were in excess of what is needed.
Delegates were also asked their thoughts on ship-to- shore LNG transfer composite hoses. 52% believe they are fit-for-purpose, 44% said they were adequate, but there are better options, 2% thought they have had their day and 2% they are a hazard.
Panellists at Riviera’s New twists on marine loading arms and hoses were OCIMF engineering adviser Ricardo Martinez and Gutteling Group managing director Sander Verweij.
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