LNG Equipment

Thrust-equalising
Thrust-equalising mechanisms balance thrust across the entire operating flow range, removing axial bearing loads. The system, which can be located either upstream or downstream of the motor, keeps the motor at discharge pressure, preventing vapour from forming in the motor housing.

Bearing configuration
Due to the poor lubricating qualities of cryogenic fluids, LNG pumps use specialised durable rolling-element bearings that can tolerate thrust in either direction and handle load reversals. Pumps associated with variable frequency drives (VFDs) may have ceramic ball bearings to prevent arcing due to eddy currents.

Junction box assembly and electrical penetrations
Electricity is connected to the submerged pumps through specialised junction boxes. As a penetration point between the LNG within the tank and the external atmosphere, the junction box and the electrical feed-through assemblies must be composed of appropriate materials and the design should incorporate various redundancies to prevent gas leakage to ensure safety.

Vibration monitoring
Vibration monitoring systems alert operators to potential cavitation and operation outside set parameters, which could indicate the presence of vapour, meaning LNG is converting to natural gas.

Testing cryogenic LNG pumps
As a result of the unique design of LNG pumps and the operating temperatures required, they cannot be tested using water, and must be tested with LNG to verify performance as close to the conditions of actual use as possible.