Sloshing: testing and assessment solutions for LNG tankers

Sloshing: testing and assessment solutions for LNG tankers

Natural gas serves as an alternative energy source and is transported by special LNG (Liquefied Natural Gas) tankers around the world. Their tank structures have to withstand movements of LNG – the so-called sloshing – even in heavy swells. Kistler provides research laboratories worldwide with application-specific pressure sensors – including IEPE and very compact solutions – for sloshing testing and assessment.

Natural gas can only be transported efficiently in liquefied form. Cooling the gas to –162°C (–260°F) makes its volume 600 times smaller, so it can be transported by LNG tankers. Wind and waves can cause movements of the LNG in partially filled ship tanks. These movements – known as sloshing – can affect ship stability and may expose the internal tank membranes to heavy loads.

Many research laboratories throughout the world study the sloshing-induced dynamic loads on the tank structures of LNG tankers. Sloshing testing and assessment procedures usually involve a rectangular 2D model of an LNG tank on a hexapod; small-scale 3D models are also used. The pressure sensors are usually deployed in cluster configurations on the tank model wall, at various locations where severe impacts are most likely.

Pressure sensors with small dimensions

A small front diameter is one of the key requirements for the sensors in this application. Thanks to this configuration, the sensors can be installed as close to one another as possible so as to optimize spatial resolution.

Pressure sensors with fast rise times and high natural frequencies

Impact pressures are largely dependent on induced motion. They can range from 50 mbar to 7 bar, with fast rise times of between 1 and 10 ms. These conditions require pressure sensors with fast rise times and/or high natural frequencies.

This application requires a considerable number of sensors, so a cost-effective measuring chain solution is essential. Thanks to IEPE technology, the pressure sensors can be connected directly to the DAQ system with no need for costly charge amplifiers.

Pressure sensors with low thermal shock sensitivity

Measured impact pressures may be affected by a pressure sensor's thermal shock behavior. The design of Kistler's 601C series features very low sensitivity to thermal shock, so these sensors are highly suitable for measuring impact pressures due to sloshing.

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