Assessing Fire Safety in Maritime Composite Superstructures –- A Risk-Based Approach

Abstract

Reduced weight and maintenance make it advantageous to replace steel with Fibre Reinforced Polymer (FRP) composites in maritime applications, but being combustible makes fire safety a burning issue. A new methodology in regulations has opened up for innovative design solutions if they can be regarded as safe as a design complying with all prescriptive requirements. However, an uneven safety level in regulations and unclear connections with objectives and functional requirements make it problematic to distinguish the level of fire safety in prescriptive requirements. This report provides an approach to clarify effects to the implicit fire safety when implementing an FRP composite superstructure to a passenger ship. FRP composites were considered with thermal insulation as a basic requirement for all interior surfaces, which keeps it thermally insulated for 60 minutes in case of fire. In order to establish how this conceptual design affects the prescribed level of fire safety, five qualitative analyses were performed, investigating (1) the fire safety regulations, (2) the fire safety objectives and functional require- ments, (3) the fire safety structure, (4) the fire safety properties and (5) the fire development. The analyses showed on possible improved containment of fire and enhanced evacuation conditions within the first 60 minutes of a fire in the novel structure. After 60 minutes there may, however, be negative effects necessary to consider, such as an increased production of toxic smoke. Furthermore, if exterior surfaces are considered in the design, these will need special attention since they are combustible and outside the scope of current regulations. With the verification needs established, the report presents a risk- based approach to assess the fire safety in FRP composite designs. It consists of a risk analysis process in line with the methodology required when deviating from prescriptive fire safety requirements. It considers the previously revealed effects to fire safety and is adaptable to the intended scope of the novel design.