IMO releases IACS feedback on FRP guidelines for ships

The International Maritime Organization published a document submitted by the International Association of Classification Societies (IACS), providing initial feedback on a draft proposal for revising the interim guidelines for the use of Fibre-Reinforced Plastics (FRP) in ship structures. This draft, outlined in document SDC 11/11, stems from the work of the Correspondence Group on this topic. The IACS submission highlights key considerations regarding fire safety, structural roles, and regulatory requirements for FRP usage in ships.

Key Points of the Document:

Title and Scope of the Guidelines

The draft proposal suggests broadening the guidelines' title to encompass the use of FRP in ship structures generally, removing specific references to "elements" and "fire safety issues." While IACS supports considering wider applications of FRP, it cautions that this change could shift the guidelines' scope. Currently, the guidelines focus on fire safety aspects of FRP elements, and IACS advises maintaining this focus unless explicitly redefined.

References to Global Strength

The draft proposes removing the phrase "FRP composite structures contributing to global strength" from paragraph 1.2 of the guidelines. IACS opposes this removal, noting the absence of significant experience with FRP structures contributing to global strength in SOLAS-compliant ships. It recommends retaining the reference until there is more practical knowledge in this area.

Definition of “Load-Bearing Element”

A new definition for “load-bearing element” is proposed in the draft guidelines. IACS disagrees with this definition, arguing that it oversimplifies structural distinctions. Instead, it suggests categorizing FRP elements into three groups based on their role:

Non-load-bearing elements that do not contribute to global strength.
Load-bearing elements that do not contribute to global strength.
Elements that contribute to global strength. This approach ensures tailored requirements for different structural roles.

Use of FRP Under SOLAS Regulations

The guidelines note that SOLAS generally requires non-combustible materials in ship structures but allows alternative designs under specific conditions outlined in regulation II-2/17. IACS agrees that such alternative designs could be feasible for small FRP components but emphasizes the challenges of applying them to larger FRP structures. It highlights the importance of fire safety compliance, referencing the definition of non-combustible materials in SOLAS regulation II-2/3.33 and testing requirements under the 2010 FTP Code.