Custom Projects: Monitoring LNG Sloshing with SENSFIB
In the LNG sector, the safety and efficiency of containment systems are critical. Yet even the most advanced membrane-type LNG tanks face an enduring challenge known as ‘sloshing’.
Sloshing refers to the movement of LNG inside a partially filled tank, often intensified during certain sea states or when tanks are loaded unevenly. This dynamic motion can generate powerful forces, known as sloshing loads, which impact tank walls, pump towers, and the inner hull structure. While incidents are rare, severe sloshing can lead to internal damage, costly repairs, or even cargo release. As LNG carriers grow in size and operate across more diverse trading routes, the need to understand and manage these loads becomes increasingly urgent.
Why traditional approaches fall short
Traditionally, sloshing has been monitored using simple counters that record the number of impacts without evaluating their severity. This can lead to conservative maintenance regimes and, in many cases, unnecessary tank inspections or operational downtime. To significantly reduce maintenance and downtime costs, operators require more accurate, real-time insights into structural integrity.
From counting to understanding
SENSFIB offers a more intelligent solution than simply counting impacts. Rather than just recording impact frequency, it measures the magnitude of each incident using advanced fibre optic sensors. These sensors are installed in key locations within the tanks, such as the upper corners and lower-fill zones, and provide high-resolution, real-time data on structural stress.
This information is processed via the SENSFIB software suite, offering immediate alerts on sloshing intensity and cumulative fatigue. Over time, the data provides a clear picture of structural loading patterns, allowing for more precise inspection planning and lifecycle maintenance.
Turning data into lifecycle value
Membrane and semi-membrane tanks, widely used in the LNG fleet, are particularly vulnerable to sloshing due to their flexibility. These structures are prone to deformation under repeated impact. SENSFIB mitigates this risk by not only tracking the severity and frequency of impacts but also by identifying the conditions that cause them. For example, partial loading combined with certain wave patterns can lead to resonance, significantly increasing structural stress.
Although classification societies acknowledge the importance of accounting for these effects in design and operation, shipowners often lack the tools to respond effectively. SENSFIB bridges this gap by providing actionable early warnings and supporting data for Risk-Based Inspection (RBI) programmes. This can reduce the frequency of mandatory inspections, lower operating costs, and extend the lifespan of tank components.
Operational benefits beyond safety
The benefits of SENSFIB extend well beyond immediate safety assurance. By pinpointing when and where structural stress occurs, shipowners and operators can move to condition-based maintenance, reducing unnecessary drydocking and optimising inspection intervals. This
proactive approach aligns with modern fleet strategies and supports discussions with class societies around inspection regimes and survey flexibility.
In today’s LNG landscape, where vessels are larger, voyages longer, and operations more complex, SENSFIB provides essential structural intelligence. It transforms sloshing from an unpredictable risk into a quantifiable parameter, allowing for better decision-making, reduced costs, and enhanced safety.
For operators of membrane-type LNG carriers, this level of insight can be the difference between maintaining peak performance and dealing with unforeseen failures.