French LNG cargo containment specialist GTT has won approval in principle (AiP) for a digital solution that assesses sloshing activity virtually, allowing the frequency of tank inspections to be cut saving cash for both charterers and owners.

The company said it had obtained AiP from Lloyd’s Register for its solution, which aims to optimise LNG membrane tank maintenance by extending the tank survey period.

“This will translate into increased operational flexibility and substantial cost savings for shipowners and charterers,” the designer said.

GTT said the project was conducted in close collaboration with Shell International Trading and Shipping Company Limited.

Speaking to TradeWinds, GTT vice president of digital Anouar Kiassi said that under existing regulations LNG carrier cargo tanks have to be opened and inspected every five years — a process that would likely take 10 days to two weeks.

The main objective is to spot fatigue and any damage to the cargo containment system and the internal pump tower.

Kiassi explained that GTT designs its LNG cargo tanks to operate for 40 years based on the sailing conditions in the North Atlantic — some of the harshest waters. However, in reality, vessels do not work there 100% of the time.

Under its new solution, GTT is proposing monitoring the real-time operation of vessels to demonstrate that periods of eight to 10 years of normal operations are equivalent or less stressful to the membrane containment system than five years in the North Atlantic.

Kiassi said GTT’s new maintenance optimisation process involves two stages.

In the first, the administrative and engineering phase, a risk assessment of a vessel is completed and submitted for flag state and class approval.

In the second, the vessel is fitted with a motion reference unit connected to a server with the latter also linked to the integrated automation system of the ship so tank filling level data can also be collected.

In its laboratory, GTT uses hexapods that move small-scale cargo tanks to follow the real-time motion of the LNG carrier. Virtual sloshing sensors in these tanks measure the impact of the cargo movement so the company can associate the motion and the resulting fatigue or impact on the containment system and pump tower.

Kiassi explained that it is a machine-learning process and can be done for any class of LNG carrier.

The data is passed through GTT’s software to give accumulated fatigue over time for the two critical inspection items, and from the trend, it is possible to see how to extend the survey time beyond five years.

Kissai said the driver for the new maintenance solution was largely charterers, which have been challenging the need for such frequent inspections. One indicated it could save their company between $2m to $3m every five years, whereas the digital VP said the savings for owners are likely to be in the hundreds of thousands of dollars.

GTT chairman and chief executive Philippe Berterottiere said: “Artificial intelligence combined with GTT’s LNG core expertise has made it possible to develop this unique solution to help shipowners and charterers reduce their operational costs without compromising vessel safety.

“We believe that this solution has the potential to become an industry-standard in the years to come.