LNG tanks operate under extreme conditions. The inner wall is exposed to cryogenic temperatures around -169°C, causing significant thermal contraction during every loading and unloading cycle. This causes the inner wall to sink or shift horizontally relative to the outer wall. Because the annular space between the walls is permanently sealed and physically inaccessible, these movements are completely invisible without purpose-built instrumentation. Left undetected, they can lead to catastrophic structural failure or leakage.
Cryogenic thermal contraction refers to the physical shrinkage of the inner wall of an LNG storage tank as it is cooled to the operating temperature of liquefied natural gas, approximately -169°C. This contraction causes the inner wall to sink vertically and shift horizontally relative to the stable outer wall. Because these movements happen inside the sealed annular space, they cannot be observed or measured through conventional inspection methods — only through permanently installed structural monitoring sensors.
The annular space of an LNG tank cannot be physically inspected once construction is complete, because it is permanently sealed and filled with perlite insulation. The only way to obtain reliable data from within the annular space is through sensors installed before sealing during the original construction phase. These include fiber optic Tank Movement Monitoring Systems (TMMS), Distributed Temperature Sensors (DTS) for leak detection, and structural strain gauges embedded in the surrounding concrete.
Yes, and the regulatory landscape is always evolving. There are currently Federal regulations in parts of the world that mandate Linear and Rotational Tank Movement Indicators for LNG facilities.
The TMMS is Roctest’s purpose-built solution for monitoring differential movement between the inner and outer walls of an LNG tank. Specialized equipment is permanently installed during construction and continuously measures movement once the tank becomes operational. It monitors inner wall movement due to thermal cooling as well as any unexpected structural settlement or rotational shifts — providing early warning data that no other system can match.
The TMMS uses intrinsically safe fiber optic sensors specifically engineered for permanent deployment in cryogenic environments. They are rated to withstand -169°C on a continuous basis which are the same temperature the inner wall experiences during normal LNG operations.
TMMS equipment must be installed during the original construction of the LNG tank, before the annular space is sealed with perlite insulation. They can also monitor tank behavior during the Hydrotesting phase. Once the tank is sealed, installation is no longer possible. This makes early engagement during the Front End Engineering Design (FEED) phase or EPC planning critical — monitoring architecture must be designed into the construction sequence, not added as an afterthought.
Yes. Roctest’s integrated sensing ecosystem is designed for full LNG terminal surveillance, covering structural integrity of tanks, leak detection in the annular space, underground LNG storage facility deformation monitoring, as well as monitoring pipelines from the jetty to the tanks, and real-time safety assessment following seismic or fire events. All data feeds into a single control room PLC alongside daily operational information.
Yes. Roctest’s monitoring systems are designed to work with virtually any standard industrial protocol, including Modbus, and can integrate with any existing PLC platform. The goal is a single unified data environment, not another isolated monitoring silo
