design considerations for aluminum hull structures - Ship Structure ...

-62-(c)(d)(e)(f)T~e exterior side of the machinery casing, where this surface isnormally exposed bare metal as in the crew sto~es and servicea~eas.Bulkheads separating stores and se~vice spacesexposed bare metal.Galley and pantry bulkheads require additionalthat normally fitted for thermal conditions.Other minor cases.which are normallyprotection overWith regard to the lower suxface of the decks, it is apparent that witha maximum allowable aluminum temperature of 400 degrees F, and a requiredtest of 1700 degrees F, an insulated construction is mandatory.For the upper surface of aluminum decks in the presence of a fire withinquarters, equivalent to the Standard Time Curve, the following observationsare noted: The “Nantasketfltests, Reference (s4) indicated that the deckcovering restricted the downward propagation of flame, provided the coveringwas of an incombustible nature. This was largely due to the lack of oxygenat floor level, the products of combustion at this level, and the rising ofheated air. This point was also illustrated by the Stateroom Fire TestReport, Reference (58). In this case with bare aluminum deck, the aluminumreached a temperature of 400 degrees F within 18 to 2S minutes. The maximumtemperature reached was only approximately 675 degrees F at 3S minutes,afber which the temperature declined. The British Test, “Fire Protectionin Passenger Ships~l,Reference (~~), with a 3/16 inch sand filled latexunderlay and I/8 inch thermoplastic resin bonded tiles, resulted in a maximumaluminum temperature of 425 degrees and 2g0 degrees on two isolatedthermocouples at the end of SO minutes.From the above, it can be assumed that a lesser degree of protectioncanbepermitted within the quarters to protect the upper surface of the decks thanis required on the underside.Therefore, the decks requiring additional probectiioncan be groupedunder the following categories:(a)(b)(c)(d)(e)Above the ~ormal stateroom ceilings, insulation must be added.ksulation protection must be added in those spaces exposed tothe weather, in addition to that normally fitted with thermalinsulation.insulation must be fitted to the overhead of nonair-conditionedspaces when located under air-conditioned spaces in addition tothe thermal insulation normally provided.Insulation is required in the overhead of stores and servicespaces located under similar spaces.All topside surfaces must be protected.The required protection resulting from the application of thesecriteria to the MV CHALLENGER of steel and aluminum construction aresmarized in Tables 11 and 12. These tables indicate that the additionalinsulation required for the aluminum deckhouse would be about 110,000pounds if tie present U. S. Coast Guard requirements are fully satisfied.