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

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.66-INSUT.ATION AND SHEATHINGShell8,000Sq.Ft.ForwardBulkhead3,6ooAfterBulkhead 1,600Underside- UpperFlat 3,720Underside- LowerFlat3,31JoTotal 20,260sq. m.With2“~fl-6#/Ft3Insul.and Sh@etMetalSheathingat5.1#/sq.Ft.= 106,000poundsadditionalweightDECKCOVERINGTop Surface - Upper Flat 3,730 Sq. Ft.Top Surface - LowerFlat 3,3110!COpSurface- TankTop 2,930Total 10,000Sq.Ft.TABLE 13 Aluminum BulkCarrier Additional Insulationand Deck Covering in MachinerySpaceWith 1“ Cellular Glass)Expanded Metal 1/h” Subkote ) = h.2#/Sq.Ft. = h2,000 pounds3/811 Magnebond )additional weightpreferable to utilize steel stanchions in lieu of inetiateclaluminumstanchions because of the disastrous results of stanchion failure.-o Spaces - Within the cargo spaces, fire protection depends uponmany variables, including the relative flammability of the anticipated cargo.If the cargo to be carried can be guaranteed to be non-flammable, therequirements for protection could ostensibly be reduced. However, in thecourse of’the shipls general service it must be assumed that a flammablecargo will be carried. It is then necessary to either prevent a fire fromstarting, or to maintain the surface temperature of the aluminum structureat an acceptable level, by fighting the fire and/or protecting the surfaces.The most promising method of preventing the start of a fire within thecargo spaces would be to fit a closed, pressurized nitrogen or carbondioxide inerting system, although the effects of this on edible cargoesand means of exhausting the hold must be studied. This system will be discussedin further detail later.Restricting the maximum temperature of the aluminum structure to 400degrees F in the presence of a fire within the cargo spaces presents manyproblems. Of the maw potential solutions considered, none have beenactually tested. All methods are subject to the following constraints:(a)(b)The intensity ofCompatibility ofthe fire for different type cargoes.the extinguishing agent with the type of cargo.(c)Effectiveness oftypes of cargo.the extinguishi~agent on fires of varying(d)System weight.(e)(f)Potenti~ damage to and loss of protection of the system, due tocargo handling whether by grab bucket, mechanized vehicles, conveyorsystem, or others.Additional cost.
-67-One method considered for maintaining strength & the alumimun strutturewas the concept ot a heat sink. A recent shore-side instal.latimutilizes a water wall column system, with circulating pumps and expansiontanks to reduce tkm amount of insulation protection required fpr steeicolqponents(Refereme (66)). Similar cowepts might be utilifiedin corlstu.mtingthe wing tanks and innerbottom within the cargo holds. Thismethod is not considered practical, however, sime it is not desirable tocar~ water ballast in these tanks when cargo is carried. This systemwould require some type of double wall transverse bulkhead construction,with consequent lOSS of cargo chic, or imreased length of cargo holdsfor equivalent ca~o cubic. An alternative method which reduaes th~ quantityof water to be circulated would utilize double wall extrusions for wingtanka, bulkheads and tank top. While this is within the state-of-the-art,it must satisfy the constraints outlined above, and would present significantfabrication problems.Conetruoting the inner surfaces of the wing and inner bottom tanksjand tranwerse bulkheads of aluminum clad with stainless steal might resultin raising the adlowable msxhum temperature of the metal befpr~ structuraltstrengthis impaired. However, this would result in high cost and wouldpresent additional fabrication constraints. .Furthertesting would beraquired.There are several proprieta~ brands of intumescent paint that retardthe spread of fire. However, it is ~tremely doubtful that these couldeffectively maintain the reqtired ~imm temperature of the structure inthe face of cargo space fire. Within the current aerospace programs, manyexotic ablative material constructionshave been developed. The totaleffectiveness of these matefials in maintaining required the-temperaturerelationshipsmust be tested am studied b determine weight and cost constraints.At this time, it appears that ablatives would be relativelyexpensive to i~til and maintain, but w~rant ~rther consideration.There is no doubt that suitable cargo hold insulation with some type ofprotective sheathing could be designed to meet the requiranents. However,whatever components are selected, it appea~ that the added cost ani weightwould retier this method unacceptable. Therefore, it is concluded Mat thecargo hold structure should not be protected. Rather, an inerting systemshould be installed which is compatible with the anticipated flsmmablecargoes, including coal anl grain. This system, in conjumtion with aproper detecting and exti~ishing system, is tinmsideredto be the bestsolution to the somewhat low risk fire problem in the cargo holds of abulk carrier.DETECTION AND EXTINGUISHING SYSTEMSThe Fhles and Regulations of the U.S. Coast Guard, for Cargo andMiscellaneous Vessels, subchapter I, Part 955 sets fOrth various requtiementsregarding fire detection and extinction which are summarized asfollows:(a)Fire detecting, manual alarm and supervised patrol systems arenot required, except in special cases.
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CONTENTSI.. II.III.Iv.v.VI ●VII.I
Page 9 and 10:
LIST OF FIGURES(Cent’d)FIGURE NO.
Page 11 and 12:
I. INTRODUCTIONThis report summariz
Page 13:
art in fabricating and maintaining
Page 16 and 17:
MONTEROSSO GRANA /17VALGRANA / CARA
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-8-Numerous references have been re
Page 20 and 21:
.10.TABLE 2. Mechanical Properties
Page 22 and 23:
TABLE 2 Mechanical Properties of Al
Page 24 and 25:
TABLE 3 Mechanical Property Limits
Page 26 and 27: -16-l?igures5, 6, 7 ati 8 present f
Page 28 and 29: -18-ti-’”’-”-””””-L
Page 30 and 31: -20-60 .r---.— ..,.— -——,L-
Page 32 and 33: .22-each stress level, rate of load
Page 34 and 35: -24-!Z456-H321 = 0.485083-H321 = 0.
Page 36 and 37: -26-(c)Members with partial or cont
Page 38 and 39: -28-AllOyS 5083 and 54.56(~ content
Page 40 and 41: -30-The previous paragraphs have de
Page 42 and 43: -32-The problem of cargo hold abras
Page 44 and 45: -34-The question of residual stress
Page 46 and 47: .36-Each alloy was given a relative
Page 48 and 49: -38-GENERAL OBSERVATIONSFYior to a
Page 50 and 51: -40-The question of comparative imp
Page 52 and 53: -42-(d)(e)Poor quality welds due to
Page 54 and 55: -44-The ABS criteria noted above we
Page 56 and 57: -46-DNV would consider fatigue in e
Page 58 and 59: -48-is less, for the exposed side s
Page 60 and 61: Equation (2):-50-Hu1l SMa~um = Hull
Page 62 and 63: -52-Another aspect of vibrations wh
Page 64 and 65: -54-000000000Bottom Shell PlateSide
Page 66 and 67: -56-at the deck and keel. This stre
Page 68 and 69: -58-AT is the change inUT= Thermal
Page 70 and 71: -60-SUl@!ARYAll parties contacted f
Page 72 and 73: -62-(c)(d)(e)(f)T~e exterior side o
Page 74 and 75: TABLE 12 Aluminum Bulk Carrier - Su
Page 78 and 79: -68-(b)(c)(d)(e)(f)(g)(h)(i)(j)At l
Page 80 and 81: -70-IIF.INSTALLATION OF SYSTEMS AND
Page 82 and 83: Rudder Assembly -carrier should be
Page 84 and 85: -74-(b)MechanicalTensile Strength 6
Page 86 and 87: -76-(e)The steel piping must be of
Page 88 and 89: -78-Other Piping Systems and Valves
Page 90 and 91: -80-struetion for the aluminum hull
Page 92 and 93: -82-Large heavy type machine~ must
Page 94 and 95: suffers attack in an alkaline envir
Page 96 and 97: -86-REPAIRSObtaining proper repairs
Page 98 and 99: -88-The design of the midship s~cti
Page 100 and 101: -90-assuming the increase is applic
Page 102 and 103: LIGHT SHIP WEIGHT ESTIMATE-92-In or
Page 104 and 105: -94-TABLE 20 Aluminum Bulk Carrier
Page 106 and 107: TABLE 22 Trim and StabilityFull Loa
Page 108 and 109: -98-TABLE 24 Price of Steel Bulk Ca
Page 110 and 111: GaseNumber. . . -.,- .TABLE 27 Comp
Page 112 and 113: -1o2-TABLE 28CarriersComparison of
Page 114 and 115: 12 ---n..T.[T7%l,=LEGS IU ORF=ErY
Page 116 and 117: -106-such as iron ore, on two of th
Page 118 and 119: -108-7)is,zg~ gg~5e mzz~E’4E!~K2j
Page 120 and 121: -11o-(a)(b)(c)(d)Inerting system fo
Page 122 and 123: -112-fatigue, particularly in the p
Page 124 and 125: -114-2k* Installation of Systems an
Page 126 and 127:
-116-LIST OF REFERENCES(7)Fatigue P
Page 128 and 129:
-11.8-LLST OF REFERENCES(Cent’d)(
Page 130 and 131:
-120-ADDITIONAL SOURCES OF INFORMAT
Page 132 and 133:
-122-redistribution of the still wa
Page 134 and 135:
-124-APPENDIX BEXCERPTS FROMRULES A
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-126-92.07-10(d)(~) Interior stairs
Page 138 and 139:
-128-~gE1+0102030- .. ..—405060
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ectintyclassification4KEYWORDSROLEL
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SHIP STRUCTURE COMMITTEE PUBLICATIO
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