I first became aware of the vulnerability of fully refrigerated LPG carriers in when examining the potential risk from collision at a UK east coast LPG terminal. The terminal was located at right angles to traffic leaving what was a relatively busy port. Regular traders included roro cargo ships, large vehicle and passenger ferries and container ships.
All the vessels turned 90 degrees to starboard close to the LPG jetty before heading out into the North Sea. Based on my own and other studies, I believe that the design of fully refrigerated LPG carriers FRLPGCs currently being built can be improved, and at various forums over the intervening years I have championed the cause for change.
I have compiled this article not as a journalist seeking eye-catching headlines but rather as a naval architect with extensive knowledge of fully refrigerated gas ship design and construction over a period close to half a century. During the late s and early s numerous research projects were undertaken relating to the possibility of a cargo spillage from gas carriers following collision damage.
The studies from research establishments, classification societies and port authorities in Europe and Japan included all types of gas carriers. Common trends were observed. However, it was repeatedly concluded that the FRLPGC, with prismatic cargo tanks, would be more at risk from collision damage than other types of gas carriers. There is a strong argument against change as there has been no collision incident involving a cargo spillage from an FRLPGC.
The industry has been fortunate to date but there is no telling when a major collision might occur. The gas shipping industry knows that complacency is not an option. In France between and the La Ciotat yard delivered 20 FRLPGCs that utilise perlite insulation, and these vessels required a double side hull construction to retain the loose perlite granules that kept LPG cargoes at the required carriage temperature.
