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

More documents

Recommendations

Info

-30-The previous paragraphs have dealt with the reaction of aluminum alloysto a salt water/salt air environment. It is also necessary to consider thecorrosive effects of potential bulk cargoes on aluminum as well as the possibilityof contamination of the cargo by the aluminum. Reference (~t.6)review”sthe compatibility of alumirnunwith a wide range of foods and chemicals, andReference (47) summarizes extensive tests of the corrosion resistance andpotential product contamination of S000 series alloys.In general, aluminum is superior to mild steel in resisting the corrosiveeffects of potential bulk cargoes, and in all cases would present lessdanger of product contamination. This results from the tenacity of the oxidefilm which forms on aluminum, which is extr~mely thin and self-healing whenscratched or abraded. This film is attacked by some fluorides and chlorides,and heavy metals (tin, mercury and copper) are unusually harmful.Table 9 indicates the corrosion resistance of ~000 series aluminumalloys relative to steel. The 11A”rating indicates equal to or better thansteel, while an AA rati~ indicates superior performance with no significantcorrosion. A rati~ of U indicates that aluminm is unsatisfactov for thisservice.In summary, aluminum is compatible with all potential dry bulk cargoeswith the exception of copper, tin or mercury ores, potassium carbonate,potassium hydroxide and trisodium phosphate. Precautions should be takenwith cargoes of aluminum fluoride, aluminum sulphate, lime and ferrous oresto minimize moisture within the hold, and the holds should be cleanedregularly to minimize build-ups of cargo residue.Abrasion ResistanceExperience with bulk carriers indicates that abrasion can present asignificant problem in several areas:(a) The flat of bottom when the ship is engaged ina trade requiringnavigation in shallow waters or across sand bars. An example ofthis is the bauxite trade in Surinam, where bulk carriers mustcross a sand bar at the mouth of the Orinoco River and thennavigate the shallow river. In this serVice, weardown of bottomplates occurs at an accelerated rate, generally resulting inrenewal of bottom plates several times during the vessel’s life.(b) The bottom and sloping bulkheads in the cargo holds. Bulldozersa~d front end loaders are often used to consolidate and move thelast of the cargo toward the center of the hatch to facilitateunloading by the grabs. In this process, the bottom and sidebulkhead plating is subjected to severe abrasion, in addition tothe impact loads resulting from unloading grabs and fallingrock cargo.The problem of bottom weardown due to abrasion is not recurrent exceptin a few specialized trades~ such as the @inoco River trade. Thereforethis problem should not influence the design of a general service bulkcam-ier such as that presently being considered. For an aluminum bulkcarrier in such a specialized trade, detailed studies of relative bottomweardown rates of aluminum and steel would be required, in conjunctionwith studies to determine the optimm balance between initial thicknessand replacement costs.
-31-TABLE 9 Relative Corrosion Resistance of Aluminum Alloys to Bulk CargoesProductAluminumFluorideCorrosionResistanceACommentThe presenceof moisturecan causerandomattackwhen in contactoverlongperiods(inexcessof2 weeks)AluminumSulphaLeAmmoniWnNitrateBorax,BoricAcidCementCoal,CoksAAAAAAGenerallythereis no problemsincethereis no free sulphuricacidprefient.Freeacidwouldresultin seriousattackifmoisturewas present.Aluminumhas a 2 or 3 to I advantageoversteel,evenwith high sulphurcontent.FlyAshl?orest ProductsGrainsGwsumLimeLimestoneIJitrogen Fer’MXEersOil (Crud@andRefined)OresPhosphateFertilizersPotashsaltSand,GravelSodaAshSodiumChlorateSodiumNitrateSodiumSulphaLe‘SugarSulphurl’risodium PhosphateAAAAAAAAA.&lAA ‘touAkolJAAAAAAAAAAAuSuperficialsurfaceattackonly.Rice,wheat,corn,etc. causeno problem.Slightlocalizedattackif wet.No problemwith dry lime. wet limeformshighlyrssistambpro”kective filmonaluminum Ṣhouldbe satisfacko~Torintermittentserviceii?the cargoiskept dry.It may be necessaryto rinseresiduefrom structure.Copper,tin and mercuryoresshouldnotbe carried. In moistconditions,builtupresiduesof ferrousorescouldca~ecorrosion.Bauxite,lead,phosphate,zincaridnickelorespresentno problems.Phosphatefertilizerscausemild etching.Potassiumchlorideis similarto salt,causingno pz-obleme.Potassiumcarbonateand potassiumhydroxideare highlycorrosiveandshouldnot be carried.Highlyconcentratedsaltwatersuchas“thatfoundin bulk shippingcauselesspittingthandilutesolutions- noproblem.Initialattackon surfacebecomesarr~fited,and continueduse in thisservicecausesno majorproblems.3 to 1 advantageover steel.Not compatible.
Page 5: 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
Page 18 and 19: -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 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 76 and 77: .66-INSUT.ATION AND SHEATHINGShell8
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
Page 136 and 137:
-126-92.07-10(d)(~) Interior stairs
Page 138 and 139:
-128-~gE1+0102030- .. ..—405060
Page 140 and 141:
ectintyclassification4KEYWORDSROLEL
Page 142:
SHIP STRUCTURE COMMITTEE PUBLICATIO
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?