DNV granted an Approval in Principle (AiP) to PASSER Marine for the development of a new LNG fuel tank insulation system in February 2021, the classification society announced.

Rendering of PASSER Marine's bonded insulation system for Type B systems. (Image courtesy of PASSER Marine)

Rendering of PASSER Marine's bonded insulation system for Type B systems. (Image courtesy of PASSER Marine)

The new concept is designed for prismatic ‘type B’ LNG fuel and cargo tanks - which according to IMO rules require a partial secondary barrier - and includes a leakage detection system capable of safely managing and containing fuel leaks.

Passer Marine noted that the insulation system is based on polyurethane spray foam, which has a proven record in IMO Type C LNG tanks, but has been modified to comply with the specific requirements of type B tanks. The partially bonded insulation will also act as a partial secondary barrier.

“The system we have developed is cost-effective and production-friendly,” said Svein Konradsen, COO of PASSER Marine AS. “The pandemic has been challenging for many companies and for the development of this particular design. The required testing has been difficult to finalise due to testing interruptions and limited possibilities to travel, but finally we have been able to submit the necessary documentation which I am very pleased to say was accepted by DNV.”

As LNG fuelled vessels are increasingly being deployed for deep-sea shipping, fuel tank sizes need to increase from 300-1000 m3 fuel capacity to up to 10,000-20,000 m3, which leaves less room for cargo.

As such, there is increased industry interest in alternative fuel tanks – known as ‘type B’ – which are prismatic in shape and more volume efficient than traditional cylindrical ‘type C’ tanks. Between 95 and 99% of LNG fuelled ships contain type C fuel tanks, but many newbuilds on order contain ‘type B’ specifications.

“There are several insulation concepts under development that provide an integrated secondary barrier and leakage detection system, but there are few proven systems available on the market,” said Monika Johannessen, DNV Maritime Head of Department, Gas Carrier Excellence Centre. “We are pleased that PASSER Marine has chosen DNV to pursue verification for this innovative concept and look forward to receiving the documentation for full approval.”