Tom Toth, Technical Manager for Offshore Integrated Mooring, Trelleborg Marine Systems
With the Petrobas’ jetty in Bahia, Brazil currently under construction and the conversion of LNGC Golar Winter to a Floating Storage and Regasification Unit (FSRU), which will be moored alongside: how important is it to have an one party with oversight of the design requirements of the FSRU, jetty and Liquefied Natural Gas Carrier (LNGC)?
FSRUs provide an economical alternative to land based fixed LNG import terminals, offering relatively short lead time to start up, significantly lower capital cost to construct and the ability to cater to difficult to access or isolated locations. They can also provide effective interim solutions before a major onshore terminal is built.
Essentially, the FSRU (a ship like facility) can take the place of an onshore LNG import terminal with a regasification plant, thereby acting as a floating LNG import terminal. The majority of FSRUs are semi-permanently moored to a land based or isolated jetty-like structure and receive natural gas in a liquefied state from LNG carriers (LNGC) that berth alongside in a moored ship-to-ship (STS) configuration.
An important consideration to ensure the success of these increasingly prevalent projects is the need for the FSRU, jetty and LNGC to be considered holistically in the design phase. To achieve efficient operation, docking and mooring solutions between FSRU, jetty and LNGC should be seamlessly integrated and developed mutually inclusively.
However, we are often finding demarcation in design of the mooring interfaces between the FSRU and jetty, and between the FSRU and LNGC. Unfortunately, the ‘greyness’ of technical specifications and the split of key components within mooring and berthing packages can often lead to interface or integration incompatibilities once the FSRU is in operation.
With the FSRU’s development entrusted to a dedicated ship designer, and the jetty being designed separately, the interfaces between the FLNG, jetty and LNGC need careful consideration with regard to the interface protocols, communications methodology and the hardware that makes the physical connections. This is to ensure that all entities work seamlessly together to avoid operational issues.
The FSRU vessel, rather than the jetty, will generally be the central control centre for loading operations and the consolidation point for mooring tension, met ocean monitoring, emergency mooring release and a host of other ship to ship and ship to shore facilities. As such, the jetty and LNGC’s operations are dependent on the FSRU, as the efficiency of the FSRU itself is dependent on smooth operations between the other two entities.
Class Rules apply to the construction and equipment installed on the FSRU, however, they are generally not applicable to the design of the jetty or the mooring system. Marine guidelines published by OCIMF and SIGTTO cover recommendations for both jetty and vessel but these are not mandatory. It is therefore important that there is a party that will cast a “birds eye view” over the entire facility, inclusively of all three entities.
The case of the Bahia LNG import terminal, which is currently under construction, could be considered an excellent model, since both the FSRU and jetty side design have been considered holistically by all the key stakeholders. Our OIM team have worked closely with the relevant parties to provide an integrated docking and mooring solution that should satisfy the operational needs of the jetty, FSRU and LNGC.
Having had an overview of the design requirements for both, we have been able to add value to the project by providing our input across both FSRU and jetty facility designers and this should ensure that the systems operational interfaces are aligned and considered well before the construction stage.
Any modifications or changes needed once the FSRU is in service will be costly and potentially impractical to implement. Such problems are easily avoided when the shared needs of FSRU, jetty and LNGC are considered holistically and developed to complement each other at the design stage.