Performance requirements for fire safety of materials in U. S. Navy ships and submarines

摘要

Demands for reduced maintenance, reduced manning, and reduced cost are resulting in the need for new and alternative materials for introduction in the fleet. The new materials in many cases tend to be non metallic and organic (combustible) materials. In order to maintain a minimum level of fire safety, the Navy has set performance requirements for new materials in many applications. These include the use of composite materials in ships and submarines. Performance requirements for composites, in most cases, are based on full scale fire tests. Use of composites for structural applications in submarines is covered by MIL-STD-2031. The use of composites aboard US Navy ships for topside applications is now covered by Fire Safety testing criteria. The recommended fire performance criteria contains requirements for fire growth, smoke toxicity, visibility (ISO 9705), fire resistance and structural integrity under fire (UL 1709). When developing new composite systems, it is expensive to repeatedly conduct these typical large scale fire tests to determine the performance of the most recent design. Instead, more cost effective small scale testing is preferable to intermittently evaluate performance. To facilitate the introduction of new and modified fire tolerant materials/systems/designs, and to reduce the financial burden on small business, the US navy has developed a low cost composite system fire screening protocol which offers the potential of predicting the full scale fire performance. Fire growth potential of new composite systems and designs can be screened by using small-scale test data from cone calorimeter (ASTM E 1354) and Lateral Ignition Flame spread Test (ASTM E 1321) in conjunction with the Composite Fire Hazard Analysis Tool (CFHAT). The small-scale Burn-Through test (2×2 ft.) was shown capable of screening fire resistance performance determined in furnace testing with a UL 1709 fire curve. These screening techniques provide cost-effective approaches for evaluating fire performance of new technologies, which in turn aids in the product development process. Full-scale fire testing is still required before inclusion of products onboard U.S. Navy submarines and surface ships.