Off Shore

Floating Production Storage and Offloading (FPSO) vessels

FPSO's are designed to receive oil and or gas from nearby platforms or subsea well heads, process the Hydrocarbon product and store it before being offloaded to a tanker or transit pipeline.  FPSO's are either constructed from new or are a conversion of a oil tanker or barge, as was the case in our experience.

The conversion of the barge to fully functioning FPSO was required to be completed within a strict schedule of 20 weeks, requiring careful planning and scheduling of various diciplines.  The requirement was for a fire protection system to protect the barge and loading facilities in event of a fire.  As the vessel was fully manned at all times the system did not incorporate detection, but comprised of sea fed fire pumps, fire mains ring, foam delivery system, hoses and fire monitors.

Some unique aspects of this project was the height of the barge, which required a 9m NPSH (Net Positive Suction Head) or the equivalent height of water that the pump can suck without causing boiling or cavitation (the formation of bubbles due to the low pressure).  Liquid can be pushed down a pipe with a great deal of force limited only by the ability of the pipe to withstand the pressure; however, a liquid cannot be pulled up a pipe with much force because bubbles are created as the liquid evaporates into a gas.

This required some careful engineering as serious damage may occur if a large pump has been sited incorrectly or with an incorrect NPSHR (required) value and this may result in a very expensive pump or installation repair or worse still failure to operate in an emergency.  Liquid temperature greatly affects NPSH and must be taken into account when expensive installations are being designed.  A pump designed with a NPSHR suitable for cold water may cavitate when pumping hot water.

Needless to say an engineered solution was found and the performance of the system was tested and approved by Lloyd's Register. The delivery time was strict requiring the testing and measurement of the foam system to take place at 1:30am, but delivered on time and to specification.